Feasibility analysis and decarbonisation strategy for existing non-residential buildings

Master's Degree Final Project Feasibility Analysis and Decarbonisation Strategy for Existing Non-Residential Buildings Submitted to the Faculty of the Escola Tècnica Superior G¶(QJLQ\HULD Industrial de Barcelona (ETSEIB) Universitat Politècnica de Catalunya (UPC) by Benjamin Barge Advisor: IVETTE MARIA RODRIGUEZ PEREZ In partial fulfilment of the requirements for the degree of MASTER IN ENERGY ENGINEERING Barcelona, September 2023 The toughest and most important battle of the 21st century will be fought without weapons. The tools of this battle are: energy efficiency, energy savings and renewable energies. -Franz Alt 1 (translated from German) 1 Franz Alt is a renowned German journalist and author, known for his work on environmental and sustainability issues. I $EVWUDFW This study addresses the urgent need for decarbonisation of existing nonresidential buildings within the framework of European climate protection goals. The primary objective is to evaluate the potential for reducing CO΍ emissions and energy intensity in a representative hotel building in Germany from 2020 to 2050. Utilizing an analysis tool based on the CRREM Risk Assessment Tool, the study establishes a climate protection plan that outlines the building's decarbonisation pathways. The analysis reveals that, despite implementing energy and CO2 saving measures, the building will fail to meet the required values by the year 2034, consequently posing a high stranding risk. Furthermore, it becomes evident that the emission factors of heating and electricity networks play a critical role in achieving the climate targets of the EU. The study suggests that additional strategies and measures are necessary to meet political climate objectives. It also emphasizes the importance of transforming local electricity and heating networks. The work identifies further research needs, particularly concerning the precise calculation of areas, energy flows, and the influence of historical preservation. These findings hold particular significance for policymakers, building owners, and energy consultants, as they elucidate the challenges and opportunities for the successful decarbonisation of existing non-residential buildings. II Table of Contents Abstract ................................................................................................................... I Table of Contents ................................................................................................... II List of Figures ...................................................................................................... VI List of Tables ««««««««««««««««««««««««««««9,, 1. Introduction ...................................................................................................... 1 1.1. Summary of the Objectives ....................................................................... 3 1.2. Scope Limitations: Excludes CCS and other Mechanisms. ...................... 3 1.3. Language and Writing Assistance Statement ........................................... 4 2. EU Challenges and Policy Objectives for Building Sector ............................... 5 2.1. The EU Energy Plan ................................................................................. 5 2.2. German Climate Protection Act................................................................. 6 2.3. Urgency and Choice of the 1.5°C Climate Goal ........................................ 7 2.4. Summary of Chapter 2 .............................................................................. 8 3. Carbon Risk Real Estate Monitor .................................................................. 10 3.1. Purpose and Emergence ........................................................................ 10 3.2. CRREM V2 Update 2023 ........................................................................ 11 3.3. Design und Methode ............................................................................... 12 3.4. Optimisation of CRREM Tools for Building Specific Decarbonisation Strategies.......................................................................................................... 15 3.4.1. Criteria and Rationality of CRREM Tool Selection ........................... 16 3.4.2. Differences and comparison of the Excel tools ................................. 16 3.5. Summary of Chapter 3 ............................................................................ 17 4. Analysis of the Building and Site ................................................................... 19 4.1. Year of Construction and Renovation ..................................................... 19 4.2. Energetic Description .............................................................................. 20 III 4.3. Climate at Site ......................................................................................... 21 4.4. Energy Supply at Site ............................................................................. 22 4.5. Usage Structure ...................................................................................... 22 4.6. Analysis of Technical Building Systems for Energy Saving Options ....... 23 4.6.1. Room Temperatures ........................................................................ 24 4.6.2. Heat .................................................................................................. 27 4.6.3. Refrigeration ..................................................................................... 30 4.6.4. Ventilation ......................................................................................... 33 4.6.5. Water use ......................................................................................... 35 4.6.6. Lighting ............................................................................................. 36 4.6.7. Building Management System .......................................................... 36 4.6.8. Counter Concept .............................................................................. 38 4.7. Building Envelope ................................................................................... 39 4.8. The Energy Performance Certificate ....................................................... 41 4.9. Summary of Chapter 4 ............................................................................ 42 5. Energy and CO΍ Analysis of the Building ...................................................... 44 5.1. Consumption Metrics .............................................................................. 44 5.1.1. District Heating ................................................................................. 44 5.1.2. Electricity .......................................................................................... 45 5.1.3. Refrigeration ..................................................................................... 46 5.1.4. Natural Gas ...................................................................................... 47 5.1.5. Summary of Chapter 5.1 .................................................................. 48 5.2. Emission Factors .................................................................................... 50 5.2.1. District Heating ................................................................................. 50 5.2.2. Electricity .......................................................................................... 52 5.2.3. Refrigeration ..................................................................................... 55 IV 5.2.4. Natural Gas ...................................................................................... 56 5.2.5. Summary of Chapter 5.2 .................................................................. 56 5.3. Overall Assessment ................................................................................ 57 5.3.1. Carbon Intensity ............................................................................... 57 5.3.2. Energy Use Intensity ........................................................................ 58 6. Energy-Saving Measures .............................................................................. 60 6.1. M1 Lighting ............................................................................................. 60 6.2. M2 Roof-Top Photovoltaik ...................................................................... 63 6.3. M3 Refrigerant Conversion ..................................................................... 64 6.4. M4 Replacing HVAC Systems ................................................................ 64 6.4.1. Electricity Saving .............................................................................. 65 6.4.2. Heat Savings .................................................................................... 65 6.5. M5 AI-based HVAC control ..................................................................... 67 6.6. Summary of Savings ............................................................................... 68 6.7. Non-considered measures ...................................................................... 69 6.7.1. Retrofit Insulation ............................................................................. 69 6.7.2. Hydraulic Balancing and Replacement of Pumps ............................. 70 7. Results .......................................................................................................... 72 8. Discussion and Outlook ................................................................................. 79 9. Conclusions ................................................................................................... 82 10. References ................................................................................................. 84 Appendices .............................................................................................................. Appendices A0: Cooling schemes from the time of the reconstruction in 2003 .. a Appendices A1: Extract form the technical inventory, protected heritage ........... b Appendices A2: Differences normalisation ......................................................... c V Appendices A3: Extract from DIN 4710 for the specification of ventilation degree hours in Berlin ..................................................................................................... d Appendices A4: Data sheet PV Module Solarwatt .............................................. e Appendices A5: Data sheet SMA inverter ............................................................ f VI /LVWRI)LJXUHV Figure 1 Average energy intensities by property type in kWh/m² as assessed for Europe by GRESB 2018. Source: CRREM ««««««««««««««««««««««« 1 Figure 2 Various elements of the Green Deal. Source: European Commission («............ 6 Figure 3: Global CO΍ emissions from energy combustion and industrial processes, 1900-2022 Source: IEA, 2023««««««««««««««««««««««««««««« 9 Figure 4 Global building sector CO΍e intensity pathways. Source: CRREM V2 2023««««« 12 Figure 5 Decarbonisation and energy reduction pathway from CRREM Risk Assessment Tool, Targets. Source: CRREM V2 Tool, 2023«««««««««««««««««««« 14 Figure 6 Decarbonisation path from CRREM Risk Assessment Tool, Asset. Source: CRREM V2 Tool, 2023««««««««««««««««««««««««...................... 15 Figure 7 Energy reduction path from CRREM Risk Assessment Tool, Asset. Source: CRREM V2 Tool, 2023««««««««««««««««««««««««««««««« 16 Figure 8 Overview different building parts A to D Source: Google Earth,2023«««««««« 21 Figure 9 Photograph of the temperature measurement in the hotel room ««««««««« 25 Figure 10 Photograph of the temperature measurement in the conference room«««««« 25 Figure 11 Permitted ranges of the operative room temperature in the heating period. Source: DIN EN 12831«««««««««««««««««««««««««««««« 26 Figure 12 Permitted ranges of the operative room temperature in the cooling period. Source: DIN EN 12831«««««««««««««««««««««««««««««« 27 Figure 13 Photograph the shower fittings during the inspection«««««««««««««.. 36 Figure 14 Photograph of the room automation in the hotel rooms««««««««««««« 39 Figure 15 Exemplary floor plan of building part 1, first floor. Source: Building plans, confidential) 40 Figure 16 Evaluation of the entire building within the scope of the energy consumption certificate Source: Building owner, confidential, 2019 ««««««««««««« 43 Figure 17 Yearly district heating consumption values 2016-2021««««««««««««« 45 Figure 18 Yearly electricity consumption values 2016 ± 2021«««««««««««««« 47 Figure 19 Yearly gas consumption values 2016 ± 2021 ««««««««««««««««« 49 Figure 20 Applied average energy consumption and total energy consumption (own illustration).««««««««««««««««««««««««««««««« 50 Figure 21 Decarbonisation path of district heating. Source: Vattenfall, 2023«««««««« 52 Figure 22 Development of specific emissions of the German electricity mix 1990-2021 and first estimates 2022 (Translated from German) Source: UBA«««««««««««« 54 Figure 23 Electricity fed in from conventional and renewable energy resources in percent Source: DeStatis, 2023««««««««««««««««««««««««««.. 55 Figure 24 Decarbonisation path of electricity according to CRREM V2, 2023 (own illustration). 56 Figure 25 Analysis of energy consumptions with and without daylightand presence detectors (own illustration) «««««««««««««««««««««««««««««.. 62 Figure 26 Summary of annual CO΍ savings per m² (own illustration) «««««««««««. 69 Figure 27 U-values of building parts A to D compared with U-value according to minimum requirements (own illustration) ««««««««««««««««««««««« 71 5 EU Challenges and Policy Objectives for Building Sector 2. EU Challenges and Policy Objectives for Building Sector This chapter provides an overview of the European and national policy frameworks and targets that form the basis for this feasibility study and the decarbonisation strategy. 2.1. The EU Energy Plan The European Green Deal is an ambitious initiative aimed at creating a decarbonized and sustainable European Union by 2050. Introduced by the European Commission in December 2019, the Green Deal responds to the growing urgency of the climate crisis and the need for decisive actions to reduce greenhouse gas emissions and transition to a more sustainable and resilient economy (European Comission, 2021). Figure 2: Various elements of the Green Deal. Source: European Commission (2019) Figure 2 summarizes the relevant sectors and principles of the Green Deal. It shows that the building sector, particularly the renovation of existing buildings, is a key element of both the Green Deal and the Renovation Wave initiative. Commercial buildings in the EU significantly contribute to overall energy consumption and greenhouse gas emissions (European Commission, 2020). EU Challenges and Policy Objectives for Building Sector 6 Another major driver for the decarbonisation of the building stock is the 'Renovation Wave' initiative. This initiative is particularly relevant for the building sector as it directly addresses the rate of energy renovation, a key factor for reducing greenhouse gas emissions in this sector. Key targets of the European Green Deal and Renovation Wave: x The EU aims to become the world's first climate-neutral continent by 2050. x At least 60% reduction in greenhouse gas emissions by 2030 compared to 2015 levels. x Doubling the renovation rate by 2030. x Promoting the renovation of existing buildings to achieve higher energy efficiency and increase their share of renewable energy. x Improving the energy efficiency of buildings and achieving their climate neutrality by 2050. (Hermelink & Bettgenhäuser, 2021) Concerning the last point about improving energy efficiency, specific metrics or target values in kWh/m² could not be found. As the European building directive is under revision during the preparation of this Master's thesis (DNR, 2023), reliable information on this is expected to be published soon. Currently, it is likely that nonresidential buildings must achieve at least energy efficiency class D by 2030 (Oekozentrum, 2023). It is an open question whether buildings under historic preservation will also be excluded from the overall building efficiency in the revised version. In summary, the European Green Deal and the Renovation Wave have set very ambitious targets to combat the environmental impacts of climate change. However, it is surprising that there are still no established benchmarks regarding the overall energy efficiency of non-residential buildings. 2.2. German Climate Protection Act The German Climate Protection Act (KSG) was enacted in 2019 by the Federal Government to implement the EU Climate Protection Act in Germany. It sets national climate protection targets and specifies the amount of greenhouse gas emissions each sector of the German economy can emit per year. The overarching 7 EU Challenges and Policy Objectives for Building Sector goal of the law is to limit global warming to well below 2 degrees Celsius and to reduce Germany's greenhouse gas emissions by at least 95% compared to 1990 levels by 2050 (Federal Government Germany (BDR), 2023). In addition to the building sector, the following six sectors are considered: energy, industry, transportation, agriculture, and waste management. The KSG has recently been tightened, requiring that the emission reduction targets can met earlier and that all six sectors achieve climate neutrality by 2045 (ibid). Therefore, the KSG is even stricter than required by the EU. This tightening has a direct impact on the decarbonisation measures examined in this Master's thesis in chapter 6 because the emission factors need to be adapted. For this study, the energy and industrial sectors are also particularly relevant alongside the building sector, as the providers of electricity and heat networks are also required to decarbonize their networks, significantly facilitating the achievement of climateneutral buildings. Due to the overarching goal of realizing decarbonisation in Europe by 2050, this Master's thesis chooses the time frame from 2020 to 2050 for the building sector to enable a uniform comparison. 2.3. Urgency and Choice of the 1.5°C Climate Goal According to the Paris Climate Agreement, the "below 2°C" and 1.5 °C targets are aimed at in order to keep maximum warming below these temperature increases by the end of the century. It is therefore often referred to as achieving the 2°C or 1.5°C target. In this study, the 1.5 °C target is aimed for. The need for greening arises from the continuously increasing greenhouse gas emissions. In 2022, another new high of 36.8 billion tonnes of CO΍ was emitted for the energy sector, causing a further shortage of CO΍ budget, which is still available. (IEA, 2023) Figure 3 illustrates these global CO΍ emissions by showing emissions from energy and industrial processes from 1900 to 2022 in Gt. EU Challenges and Policy Objectives for Building Sector 8 Figure 3: Global CO ΍ emissions from energy combustion and industrial processes, 1900-2022 Source: IEA, 2023 The Figure 3 clearly shows that after the slump during the Corona pandemic in 2020, CO΍ emissions rise very steeply. Considering the risks of climate change, the 1.5°C target serves as a critical upper limit and the basis for calculating the decarbonisation path in this study. The choice of this target enables a precise and ethically grounded analysis of the measures needed to achieve climate goals. It represents not only a technical challenge but also an ethical obligation to future generations. The target provides important guidelines for political decisions, technological innovations, and societal efforts. 2.4. Summary of Chapter 2 The chapter outlines the European and German policy frameworks and objectives that guide the decarbonisation strategy of this feasibility study. It highlights the European Green Deal and the Renovation Wave initiative as critical drivers for reducing greenhouse gas emissions and enhancing energy efficiency in the building sector. Key targets include achieving climate neutrality by 2050, reducing greenhouse gas emissions by at least 60% by 2030 compared to 2015 levels, and doubling the renovation rate. Despite these ambitious goals, the chapter notes the 9 EU Challenges and Policy Objectives for Building Sector absence of specific benchmarks for overall energy efficiency in non-residential buildings. In the German context, the Climate Protection Act serves as the national legislation to enforce EU climate goals. It aims to reduce Germany's greenhouse gas emissions by at least 95% compared to 1990 levels by 2050. The law has been tightened recently to accelerate climate neutrality across various sectors, including buildings, by 2045. The chapter also emphasizes the urgency of adopting the 1.5°C climate target, citing increasing global CO΍ emissions. The target serves as the basis for the decarbonisation path in this study and represents both a technical challenge and an ethical obligation. Carbon Risk Real Estate Monitor 10 3. Carbon Risk Real Estate Monitor In the following sections, the CO΍ emission and energy intensity targets have been calculated. These values represent the threshold between meeting climate goals and facing a stranding risk. This chapter explains how the decarbonisation and final energy pathway targets were calculated using CRREM V2 from 2023. 3.1. Purpose and Emergence The CRREM Risk and Assessment Tool is an instrument that was developed in 2018 as part of the European Union's Horizon 2020 project. It was created by the Institute for Real Estate Economics (IIÖ) in collaboration with academic institutions such as the University of Ulster, Universidad de Alicante, and others, as well as the Global Real Estate Sustainability Benchmark (GRESB), an organization in the sustainability sector of real estate. Their common goal was to make the stranding risk in the real estate sector recognizable and reducible (IIÖ, et al., 2023). he stranding risk refers to the danger of a significant loss of value of assets due to external factors. These factors include climate-related events, natural disasters, or regulatory changes, such as the pricing of CO΍. This can be particularly relevant for assets like coal-fired power plants. In the context of buildings, stranding risk also arises from an increase in costs due to regulatory changes. These cost changes also result from a growing demand for sustainable buildings, leading to reduced interest in buildings with poor energy efficiency (Lange & Burgess, 2017). For this reason, the tool is often used by real estate professionals and investors. They use it to gain an assessment when buying or selling real estate. This allows determining whether a specific building can achieve the EU's climate goals or to what extent measures need to be taken to prevent stranding of the property. But it is also used by engineers in technical building equipment or sustainability consulting who develop decarbonisation strategies for buildings, even though it has limitations regarding the number and level of detail of energy-saving measures and individual emissions metrics, as demonstrated in the following sections. 11 Carbon Risk Real Estate Monitor 3.2. CRREM V2 Update 2023 In the spring of 2023, and during the preparation of this study, the revised version CRREM V2 was released. The update incorporates tightening measures concerning decarbonisation pathways due to the ongoing increase in global CO΍ emissions. recalculated, and the starting budget was corrected from 320 Gt Co2 to 291 Gt CO΍. For the new version CRREM V2, the global budgets were recalculated and the starting budget was corrected from 320 Gt CO΍ to 291 Gt CO΍. (Bienert, et al., 2023). Furthermore, the transmission and distribution losses (T&D losses) of the networks have been removed from the decarbonisation path, as these have already been allocated to the energy sector (Bienert et al., 2023). The intensification is illustrated in Figure 4. Figure 4: Global building sector CO ΍ e intensity pathways. Source: CRREM V2, 2023 It can be observed in Figure 4, that initially, no intensification occurs; in fact, the decarbonisation line of CRREM V2 is slightly above that of the first version. This is attributed to the fact that the T&D losses ensure that the curve is less steep. Another factor is that the electricity networks have undergone a faster decarbonisation than anticipated (ibid), although this varies significantly by country. For the case under consideration in Germany, the Figures from the Federal Environment Agency Carbon Risk Real Estate Monitor 12 Germany (UBA) in their 2023 report on CO΍ emissions per kWh of electricity confirm this statement (also refer to Figure 22 in Chapter 5.2.2). However, this illustrates how rapidly these values can fluctuate due to global influences such as the COVID19 pandemic or the conflict in Ukraine. As can be seen further along the curve, the positive effect is reversed in 2025. The intensification of the pathways is primarily justified by the continued increase and resulting reduction in the global CO΍ budget, as well as a sectoral overshoot (ibid). By 2050, the target values have converged again, but the updated values remain below those of V1. The rationale is likely to once again be related to the reduced CO΍ budget and the overshoot. 3.3. Design and Methode The CRREM V2 Excel tool provides an option in its first relevant tab, "Targets," to select the desired climate target for a particular building type (residential, hotel, retail, etc.) in an EU country. Initially, the tool presents users with specific GHG and Energy Intensity reduction pathways from 2020 to 2050. These pathways are crucial as they represent the maximum levels the building can achieve without being classified as a "Stranding Risk." Figure 5 illustrates an example for a hotel targeting a 1.5°C pathway in Germany. 13 Carbon Risk Real Estate Monitor Figure 5: Decarbonisation and energy reduction pathway from CRREM V2 Risk Assessment Tool. Source: CRREM, 2023 In addition to CO΍ emissions generated from heat and electricity production, the tool allows for the inclusion of fluorinated greenhouse gases (F-gases) in the calculations. These gases are used in refrigeration and air conditioning and contribute approximately 20% of a building's total greenhouse gas emissions, depending on the building type (see Bienert et al., 2023). Therefore, they are a vital component of the decarbonisation pathway. To account for this factor in the tool, information on the refrigerant and the annual leakage rate is required. The results appear in the "Asset" tab of the Excel tool after entering the building data. Figures 6 and 7 display target pathways (green curve) on a timeline from 2020 to 2050 that the building should adhere to in order not to be classified as a "Stranding Risk." The black lines represent the building's projected CO΍e consumption and energy intensity. It's important to note that, at this point, no energy-saving measures have been implemented for the asset. The slope in the decarbonisation curve in Figure 6 arises only from taking into account the decarbonisation of the electrical and heating grids, as well as climate-induced Carbon Risk Real Estate Monitor 14 changes in heating and cooling degree days (HDD/CDD). Without these factors, the GHG intensity would remain at its initial level, as indicated by the dashed line. Interestingly, the building-specific black line of the Energy Reduction Pathway in Figure 7 only drops slightly. This suggests that global warming apparently leads to less heating and more cooling, resulting in reduced energy consumption. Figures 6 and 7 reveal that the black lines exceed the green lines from 2030 or 2028 onwards. In this case, the building consumes more energy or emits more GHGs than prescribed in the target pathway, indicating a Stranding Risk. Implementing one or more energy-efficient measures can reduce CO΍ consumption, mitigate surplus emissions, and decrease the risk. Figure 6: Decarbonisation path from CRREM Risk Assessment Tool, Asset. Source: CRREM V2 Tool, 2023 21 Analysis of the Building and Site Supplementary meeting areas, relaxation zones, various storage capacities, and a currently unused parking unit are also present. The building design incorporates two courtyards to ensure adequate natural lighting. The building envelope, primarily a combination of masonry and reinforced concrete dating back to the early 20th century, includes various facade designs. These designs feature brickwork, textured plaster, and different thermal insulation composite systems from the early 2000s. In accordance with confidential summer thermal protection guidelines, modernization occurred during construction phases in the early 21st century. This modernization accounts for approximately 20% of the building envelope, including the exterior walls of the new building and the roof insulation. Window systems in the building vary, ranging from wooden frame windows with insulating glass to metal post-and-beam facades in specific areas. These windows achieve a good energy level, particularly in terms of summer heat insulation. For summer heat protection, automatic vertical awnings are installed, thus reducing the cooling requirements. The roof structures are either insulated flat roofs or pitched roofs with tile cladding. An additional glass roof installed over one of the courtyards minimizes the need for artificial lighting in the areas below. Heat generation and distribution in the building are managed through district heating and various static and dynamic heating systems. Approximately 90% of the assessed water and heating pumps are controllable high-efficiency pumps. These pumps have the potential to significantly reduce electricity consumption, especially since they typically operate 24/7 during the winter months. Various ventilation and air conditioning systems, located on the roof, handle room conditioning. The building's technical systems are primarily controlled centrally through a building automation system, supplemented by room-specific automation solutions. An overarching building management system enables centralized control settings. 4.3. Climate at Site The studied region is characterized by a temperate climate, which neither exhibits extreme heat nor cold. The average annual temperature in this region is around Analysis of the Building and Site 22 10.1°C. Typically, July is the hottest month, with average temperatures reaching approximately 19.8°C. Conversely, January is usually the coldest month, with an average temperature of about 0.5°C. Regarding solar irradiance, June is the most sunlit month, with an average of approximately 10.9 hours of sunshine per day, totalling roughly 338 hours for the month. On the other hand, January is the month with the least amount of solar irradiance, averaging only about 2.58 hours of sunshine per day and a cumulative total of approximately 80 hours for the entire month. Overall, the region receives about 2479 hours of sunshine annually (climate-data, 2021). The irradiance values on rooftops range approximately between 1050 and 1150 kWh/m²/a (Energy atlas, 2023). Due to the temperate climate, the heating demand in the winter months and the cooling demand in the summer months are likely to be moderate. The high number of sunny hours in June and the rooftop irradiance values suggest that installing photovoltaic systems in this region could be advantageous. 4.4. Energy Supply at Site The property has an electricity and district heating supply from the local utility. The electricity supplier is the municipal electricity supplier ³Vattenfall´. No information is available from the owner or operator regarding green power purchases, so it is assumed that the adjacent electricity and the electricity mix for the country are used. Furthermore, there is a natural-gas supply for individual appliances in the kitchen area. 4.5. Usage Structure In addition to hotel rooms, the hotel building includes other areas of use, such as the restaurant and spa. The occupancy rate of the hotel is estimated to be 90% annually, taken into account while designing measures. The details regarding various areas and their operating hours are presented in Table 1. 23 Analysis of the Building and Site Table 1: Operational time Monday - Sunday Definition of use Use Times of use Hotel room Monday - Sunday 0:00 - 24:00 Conference rooms Monday - Sunday 0:00 - 24:00 Kitchen Monday - Sunday 5:30 - 21:30 Restaurant / Bar Monday - Sunday 7:00 - 22:00 Fitness / Sauna Monday - Sunday 17:00 - 22:00 Lobby / Reception Monday - Sunday 0:00 - 24:00 Office Monday - Friday 7:00 - 16:30 Other (ancillary areas, traffic routes, technical areas, etc.) Monday - Sunday 0:00 - 24:00 Underground car park (currently not in used) - - Table 1 clearly shows that the building is open around the clock. This is significant for energy analysis since it can be assumed that the HVAC equipment is continuously running and consuming electricity and heat. 4.6. Analysis of Technical Building Systems for Energy Saving Options In this chapter, the technical building systems and areas are analysed to identify any potential savings. For this purpose, the individual building components are briefly introduced and then the current status in the building is explained. The assessment is based on the site visit and the technical documents that were provided. Where information was not available, standard values were estimated from literature or from experience. The chapter provides information on the energyconsuming devices or areas of the building under consideration. Analysis of the Building and Site 24 4.6.1. Room Temperatures The planning documents with the design temperatures for the individual areas could not be provided by the operator. However, the temperatures listed below were taken from the building control system during the building inspection: x Hotel room 21°C x Conference areas 21°C x Restaurant 20°C x WC rooms 20°C x Changing rooms staff 22°C x Fitness area 22°C x Corridors/staircases 18°C During the on-site inspection (heating period), the indoor temperature was measured in a standard hotel room as an example. A photographic snapshot of the prevailing temperature is shown in Figure 9 and Figure 10. Figure 9 shows the display of a temperature measuring device that was set up for building inspection and with which the indoor temperature Ti and the indoor wall temperature Tw were measured. The measurement showed that the internal temperature in the standard room was 24.7 °C. Based on the wall temperature and measurement of the external temperature, the heat transfer coefficient of the wall could be measured, but this was not necessarily due to the available documentation and can therefore be ignored. Figure 10 is from a fixed temperature sensor on site. It indicates that the default temperature in the conference rooms is set to 23 °C. 25 Analysis of the Building and Site Figure 9:Photo of the temperature measurement in the hotel room the 25.10.2022 Figure 10: Photo of the temperature measurement in the conference room on 25.10.2022 At the time of the renovation, reference values from DIN EN 15251 [1, Tab. A.2] and the German occupational health and safety guideline [ASR A3.5 Tab. 1] were presumably used for thermal comfort in non-residential buildings. These values can also be transferred to training, conference and meeting rooms. There the bandwidths are defined for the minimum and maximum operative room temperatures that are to be ensured by the room conditioning during the time of use and may only be exceeded during a defined period. To increase thermal comfort, lower bandwidths of the permissible operative temperature and shorter exceeding times are provided. Depending on these parameters, thermal comfort is divided into categories A (high comfort) to C (normal comfort). For living areas and ancillary rooms such as storage rooms, changing rooms and showers, the room temperature recommendations of DIN EN 12831 can be used. The Figure 11 shows the reference values of the operative temperature according to categories A-C during the heating period as well as the estimated temperature range between 20 and 25 °C during operation. Analysis of the Building and Site 26 Figure 11: Permitted ranges of the operative room temperature in the heating period. Source: DIN EN 12831 Figure 12 also shows the operative temperatures, but for the cooling period in summer. Figure 12: Permitted ranges of the operative room temperature in the cooling period. Source: DIN EN 12831 At the time of writing the thesis, no information is available on the actual operating temperatures in the building. From the information provided by the building control system, measured temperatures, and reference values from standards, it can be deduced that the temperatures in the interior of the building cannot be determined exactly. However, based on the measured temperature, it can be assumed that the comfort level corresponds to category C according to DIN EN 15251. Therefore, the temperatures range in this thesis are determined based on the measured values, the data from the room temperature thermostats, and the standard values from the German standards. Consequently, it is assumed that the 0 5 10 15 20 25 30 Category A (high comfort) Category B (increased comfort) Category C (normal comfort) Estimated operating temperatures range Permitted ranges of the operative room temperature during heating season [C]. 0 5 10 15 20 25 30 Category A (high comfort) Category B (increased comfort) Category C (normal comfort) Estimated operating temperatures range Permitted ranges of the operative room temperature in the cooling period [C]. 27 Analysis of the Building and Site temperatures vary between 19 and 25 °C in summer and between 21 and 25 °C in winter. 4.6.2. Heat 4.6.2.1. Heat Generation The heating energy for the property is provided by district heating. The district heating connection and the transfer station are located in the basement of building section 2. The district heating transfer station consists of a total of four heat exchangers, which are divided into 2 x 2 heat exchangers for heating and hot water operation, the total output is approx. 1,590 kW as stated in Table 2. According to building specifications, the system temperatures are 120 °C in the flow and 55 °C in the return in winter and 80 / 40 °C in summer. Table 2 summarises the information about the heating system in the Hotel gathered from the technical descriptions and during the inspection: Table 2: Summary heat supply Heat Supply: District Heating Producer type District heating, Vattenfall Generation Power Heating: 2x heat exchanger each about 550 kW Hot water: 1x heat exchanger 320 kW 1x heat exchanger 160 kW Primary temperature spread Winter: 120 / 55 °C Summer: 80 / 40 °C Distributon Number of circles 6 Number of pumps 4 Secondary temperature spread AHU line I, II and III 90 / 35°C Static heating, line I, II and III 70/ 50°C Underfloor heating 38 / 28 °C Hot water (estimate) 70 / 40°C Static power share Static heating, line II + III 519 kW Static heating, line I 388 kW Underfloor heating 26 kW Domestic hot water hotel rooms 320 kW Domestic hot water kitchen 160 kW AHU line II + III 518 kW Analysis of the Building and Site 28 Dynamic power share AHU line I 45 kW Handover Secondary use Heating coil AHUs Domestic hot water preparation Control main use Individual room control Ancillary use control Control via the supply air temperature or hot water setpoint temperature From the heating distribution in Table 2, it is evident that there are a total of 6 heating circuits supplied by 4 pumps. This presents the opportunity to connect a Building Management System to measure energy consumption and regulate it as required, resulting in energy savings. Furthermore, the input and output temperatures play a crucial role in indicating the energy distribution level. The high temperatures in Table 2 suggest that the building requires a significant amount of heat, which in turn indicates poor insulation of the building envelope. 4.6.2.2. Heat Generation for Domestic Hot Water The domestic hot water for the kitchen and the hotel area is provided by the same district heating station for heating, in each case using the storage-recharge principle. The heat exchangers of the kitchen or hotel rooms have a capacity of 480 kW. The design temperature could not be taken from the planning documents and shown in Table 2. Due to the observation during the site visit, it is assumed that the normal temperature is 40 °C, whereby the hot water pipes are temporarily heated to approx. 70 °C for legionella protection. 4.6.2.3. Heat Distribution The heat is distributed to six heating circuits at the main distributor/collector in the basement (2x air handling units, 2x static heating surfaces, 1 x underfloor heating). It appears that individual circulation pumps have been replaced in recent years. The replacement dates could not be determined on site, but it can be assumed that the replacement took place in the last 6 years. The heat is supplied to the individual consumers via properly insulated horizontal and vertical pipes and strings. 29 Analysis of the Building and Site 4.6.2.4. Heat Handover The heat is transferred to different areas of the building and to different areas of use via different systems. In the guest areas (rooms and corridors), static radiators and air handling units are installed. In all other areas, ordinary panel radiators are installed. In almost all rooms, apart from some rooms on the 5th floor, there is underfloor heating - the hydraulic connection of the underfloor heating cannot be determined from the data. In the rooms and the corridors, individual adjustment of the radiators is not possible, however, each room has an individual temperature control for the air handling units. In the conference and restaurant area on the ground floor, heat is dissipated via a combined underfloor heating system, which can also be used for cooling. The hydraulic connection of the underfloor heating in the hotel rooms is separate from the underfloor heating on the ground floor. 4.6.2.5. Heat Recovery System The building has a 58-kW heat recovery system from the commercial refrigeration. Waste heat from the condensers is fed into the heat cycle of the heat generation system in an energetically sensible manner. The waste heat generated is used to preheat or provide heating water for the heaters of AHU 3 and 4. In order to achieve the existing power target, a plate heat exchanger is installed in the line, which compensates for the missing power via the district heating. The technical specifications of the plant are listed in Table 3. It is also evident that a significantly lower temperature level prevails here compared to the heat exchangers of district heating. This lower temperature level is ideal for dynamic air-conditioning systems. Table 3: Summary heat recovery Waste heat recovery from commercial refrigeration Generation Producer type Waste heat utilisation from commercial refrigeration, serves as a pre-heating stage for the preand reheaters of the air conditioning systems. Power 58 kW Primary temperature spread 90 / Return unknown °C Secondary temperature spread 65 / 35 °C Consumer Number of pumps (waste heat generation) 2 Analysis of the Building and Site 30 Number of pumps (RLTheating coil) 3 Temperature spread All AHU 55 / 35 °C Power share static - Dynamic power share Preheater AHU 3 91 kW Reheater AHU 3 50 kW Heater AHU 4 71 kW Handover Main use Heating coil AHU Secondary use Control via the supply air temperature / room temperature The supply via district heating can be assessed as positive in relation to the location. The use of heat recovery for commercial refrigeration also contributes to the efficient use of energy in the building. 4.6.3. Refrigeration The property has a 572-kW central chiller based in the basement of the building, connected with two 400-kW recirculating chiller with Axial-fans on the roof and a 2000 l buffer tank, all date back to 2003. According to Association of German Engineers (VDI) the plants reached their theoretical technical service in 2023 (VDI, 2012). According to the technical details on the coolers, generation takes place at a temperature level of 6 / 12°C. Since the design temperature and the return temperature are in the range of the average outside temperature, it is assumed that free cooling is not used, since free cooling saves energy once the temperature difference is approx. 5 °C (IKZ-Fachplaner, 2006). A schematic of the refrigeration system is shown in the Appendices A0. The descriptions are based on the findings of the available inventory documents, the on-site inspection and the statements of the facility management. The entire building is supplied via a cooling circuit. All consumers, such as the cooling coils of the air conditioning systems, the floor cooling surfaces and the recirculating air-cooling units, are supplied via this circuit. The cooling coils of the AHU systems, as well as the duct coils that were implemented in various zones, are equipped with a twoway globe valve on the cold-water side. The amount of water supplied to the respective cooling register is influenced by the supply air temperature setpoint via an actuator. The cooling coils do not have separate pumps. These units are used exclusively for cooling the hotel rooms. 37 Analysis of the Building and Site building automation. Setpoints for conference areas, hotel rooms, restaurant, kitchen, lobby, etc. can be adjusted and monitored via this. The window contacts interrupt the energy supply of the heating/cooling system when the window is open, and a visualisation takes place within the room automation. The heating and cooling functions, as well as the ventilation parameters for individual areas, can be influenced via the individual room control. The building automation found can be rated as good. According to the FM, it was renewed in 2013. It is important that the functions and parameterisations of the building automation are checked at regular intervals and partially repaired if necessary. A different PC must be used to operate the room automation, as the software functions can only be processed via an outdated operating system. Furthermore, access is no longer available for all rooms. According to the FM, the function of the room automation of the hotel rooms in building section 1 is not continuously given. The room automation should be converted or renewed in the medium term, so that the building and room automation levels can be viewed/parameterised via a workstation, or a faultless exchange/function is given. The building has automation and information focal points that are connected to the building management system and monitor, regulate and control the heating, cooling and ventilation systems. A central room automation system is available for the building automation. Setpoint specifications for conference areas, hotel rooms, restaurant, kitchen, lobby, etc. can be adjusted and monitored through this. The heating and cooling functions as well as the ventilation parameters for individual areas can be influenced via the individual room control. Furthermore, the existing sun protection is controlled via a self-sufficient sun position control as well as a wind monitor. It is also worth mentioning that the windows in the hotel rooms have window contacts that prevent simultaneous heating or cooling. Additionally, each guest room is equipped with a room climate control unit. Figure 14 displays a photograph of the unit taken during the building inspection. Analysis of the Building and Site 38 Figure 14: Photograph of the room automation in the hotel rooms. The display in Figure 14 shows the following selectable functions: - Display of the set room temperature setpoint. - Manual input and display of the room temperature setpoint correction. - Manual input and display of the fan speed. - Automatic operation. 4.6.8. Counter Concept An important step on the way to efficient building operation is the recording and analysis of energy and media consumption in order to detect malfunctions or inefficient modes of operation of the systems. The recording of consumption values by means of meters forms the cornerstone of consumption analysis. According to the technical description, the BMS of the building records the consumption of various systems. However, this data is apparently not stored or evaluated. It was not possible to find out whether the meters are functional. A well-functioning meter structure in the building complex seems to be limited to the 4 main meters for heat, electricity, gas and water. It is not known to what extent the electricity meters are further subdivided. Neither from the property inspection nor from the available diagram of the electricity supply can conclusions be drawn about further sub-meters. In view of the technical infrastructure and the complexity of the facilities, a small-scale meter structure that enables monitoring of the technical facilities and their functioning must be taken into account. Given the type 39 Analysis of the Building and Site and use of this building, energy monitoring is essential in order to operate the facilities efficiently and economically. 4.7. Building Envelope Originally built in beginning of the 20th century, the Hotel-building was extensively refurbished and extended in early 21st century, with a focus on improving energy efficiency. This is evidenced by confidential thermal insulation certificates and measured floor plans provided by the building owner. The U-values indicate significant energy improvements to various building components like windows and roof insulations and exceed the standard values at the time by far, suggesting that extensive insulation measures were carried out on the non-heritage protected building part D to compensate for heat loss from the uninsulated, heritage protected external walls, which are characterised by their thickness of 38 to 64 mm. A section of the building's floor plan that provides more detail on the construction and layout of the building is shown in Figure 15. The double-glazed windows installed in 2002 can be observed alongside the red-marked wall thicknesses.. Figure 15: Exemplary floor plan of building part A, first floor. Source: Building plans, confidential The heritage protected façades in building parts A to C were treated conservatively - they were only dried and painted, as further renovation was not possible due to the heritage protected building regulations. Additional improvements were made in the non-heritage-protected parts of the building, including the replacement of Analysis of the Building and Site 40 windows and the renewal of the roof with improved insulation, which contributes to higher energy efficiency. Despite the efforts to optimise the energy efficiency of the building, the windows of the heritage protected conference room show a significant deviation. With a U-value of 2.4 W/(m²K), they did not meet the requirements of the Thermal Insulation Ordinance as early as 2002 and thus represent a clear deficit compared to today's standards. The windows in other parts of the building, however, meet with U-value of 1.3 to 1.6 W/(m²K) the current legal requirements. The U-values for different parts of the building envelope according to the thermal insulation certificates or if not given estimated from building standard from the time they were built, are listed in Table 8. It is notable that the external walls of building sections A to C have a high heat transfer coefficient of 1.5 W/m²K. Surprisingly, the windows in the listed building sections have a low U-value of only 1.6 W/m²K compared to the windows in the new building, which have a heat transfer coefficient only 0.3 W/m²K lower. Table 8: Building envelope areas and U-values. Component Area U-value Walls External wall old building part A-C unknown 1.50 W/m²K (estimated) External wall new building part D 0.36 W/m²K Basement unknown 0.44 W/m²K Floor Ground floor unknown 0.34 W/m²K Roof Glass roof courtyards I unknown 1.00 W/m²K Ground floor: Courtyard II unknown 0.38 W/m²K Attic: (pitched roofs + flat roofs) unknown 0.26 W/m²K Windows Windows new building part D unknown 1.30 W/m²K Windows old building part A -C unknown 1.60 W/m²K Table 8 shows that there are no areas are available from the building documentary, so the assessment for an average U-value per building component can only be estimated. Furthermore, the thermal insulation certificate describes that the exterior walls will remain in the existing building, the Uvalue is unknown, which is why U- 41 Analysis of the Building and Site value assumptions according to the building age class are used for the exterior walls. As can be seen, the U-values of the exterior walls in particular deviate significantly from the current GEG minimum requirements for renovation. Depending on the proportion of floor space, the expenditure for thermal energy could be reduced by upgrading the energy efficiency of these building components. Due to the protection of historical monuments, an energetic refurbishment of the exterior walls is fundamentally difficult. Energy-efficient refurbishment would probably only be possible from the inside. Due to the structural complexity of internal insulation on external walls and the comparatively good U-values of the other building components compared to the refurbishment standard according to the GEG, energy refurbishment would hardly result in any savings. This measure can only be recommended if the heritage protection is lifted and the exterior walls of the old building are insulated from the outside. 4.8. The Energy Performance Certificate In accordance with §§16 et seq. of the Energy Saving Ordinance (EnEV) of 18.11.2013, an energy certificate was issued for the entire hotel building on 06.12.2019. The data on the final energy consumption of heat and electricity are determined for the building on the basis of the bills for heating costs or the bills from energy suppliers. This is based on the energy consumption data of the entire building and not of the individual occupancy units. The values determined in this way are specific values per square metre of net floor area according to the EnEV. The recorded energy consumption for heating is converted to a Germany-wide average value using specific local weather data and climate factors. The information on final energy consumption gives an indication of the energy quality of the building. A low value indicates low consumption. However, it is not possible to draw conclusions about the consumption to be expected in the future. The actual consumption of a unit of use or a building deviate from the stated final energy consumption, in particular due to the influence of the weather and changing user behaviour or changing uses. The comparative values result from the assessment of similar buildings. Lower consumption values than the comparative value signal a good Analysis of the Building and Site 42 energy quality compared to the building stock of this building type. The final values of both the scales for final energy consumption, rounded to the decimal place, amount to twice the respective comparative value. Figure 16: Evaluation of the entire building within the scope of the energy consumption certificate Source: Confidential, 2019. The energy consumption certificate in Figure 16 shows that the final annual energy consumption for heating (incl. hot water) is 115.0 kWh/m²/and for electricity (incl. cooling and lighting) 105.7 kWh/m²a. These values refer to consumption from 20162018. The reference value for final heating energy consumption is 105 kWh/m²a, which means that the actual consumption is slightly higher than the reference value. The final energy consumption for electricity is excessively high for the assessed building compared to the reference building. 4.9. Summary of Chapter 4 The chapter provides an exhaustive analysis of the building, its energy consumption, and its technical systems. Built in phases, the hotel is a blend of historical and modern architecture with some energy-efficient design elements. It operates on district heating and has implemented various energy-saving options like highefficiency pumps and a heat recovery system. The building also uses water-saving (Final Energy Consumption) (Final Energy Consumption heat) (Comparative value of this building category for heating and hot water) (Hot water included) (Final Energy consumption electricity) (The value includes the power )consumption for: ) (Extra heating) (Hot Water) (Ventilation) (Installed lights) (Cooling) (Other) (Comparative value of this building category for electricity) 43 Analysis of the Building and Site fixtures to minimize domestic hot water waste. A central building management system exists but needs updating for more efficient operation. Overall, the analysis lays the groundwork for identifying areas where energy efficiency can be improved as part of the broader decarbonisation goals for the building. Energy and CO΍ Analysis of the Building 44 5. Energy and CO΍ Analysis of the Building This chapter provides information on the annual values of the different energy sources consumed by the building, together with the corresponding emission factors. Having access to reliable data on energy consumption and demand is an essential basis for assessing the current energy status and analysing potential optimisation measures. It is the only way to accurately calculate the carbon and energy intensities at the end of this chapter. 5.1. Consumption Metrics 5.1.1. District Heating Vattenfall, the energy supplier, provides district heating to the building. During the on-site inspection, the annual readings of the heat meters were checked for the years 2019 to 2020. Due to the potential impact of the Coronavirus pandemic on consumption, the district heating consumption from the energy certificates for the years 2016 to 2018 was also averaged. The determined consumption rates and the used mean value are shown in Figure 17. Figure 17: Yearly district heating consumption values 2016-2021. 1707,750 1483,730 1446,360 1818,470 1614,078 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Energy Certificate (2016 - 2018) 2019 2020 2021 Mean 2016-2021 MWh /Year Heat Consumption in MWh 45 Energy and CO΍ Analysis of the Building The graph in Figure 17 indicates that the annual heat consumption varies to a certain degree. While the consumption in the years 2019 and 2020 was 8.1 to 10.4% below the average, it was 12.7% above the average in 2021. When the building technician inquired if there had been any changes to the heating system in 2021, no answer was provided. Notably, despite multiple lockdowns in Berlin during the years 2020 and 2021 due to the COVID-19 pandemic, which led to a significant decline in overnight stays nationwide (Graefe, 2023), this decrease is not reflected in the heat consumption. On the contrary, there was an increase in heat consumption in 2021. One possible reason for this increase could be the transition of the ventilation systems from recirculated air to fresh air operation. This adaptation also emerged as a measure to mitigate virus transmission by increasing fresh air circulation within the building during the pandemic. The building technician could not confirm whether this measure has been reverted. For the analysis, the average value from 2016 to 2021 will therefore be used.: ࡱࢊࢎ ൌ૚ǡ૟૚૝ǡ૙ૠૡܓ܅ܐ ܉ 5.1.2. Electricity The building owner has not provided any evidence regarding electricity consumption. Therefore, a request was made to the network operator to obtain electricity consumption data for 2019 to 2021. Considering the potential impact of the Covid-19 pandemic on consumption, the energy consumption from energy certificates for 2016 to 2018 was also averaged. The determined consumption rates and the used mean value are shown in Figure 18. Energy and CO΍ Analysis of the Building 46 Figure 18: Yearly electricity consumption values 2016 ± 2021. The electricity consumption in 2019 was 1554 MWh, roughly 14 to 16% higher than the average, as indicated in the energy certificate according to Figure 18. In contrast, the lowest consumption occurred a year later, with 1072 MWh, which was more than 16% below the average. The low values in the years 2020 and 2021 are likely attributable to the reduced number of overnight stays due to the COVID-19 pandemic. Another contributing factor, according to the building technician, could be the gradual transition to LED lighting in the building, which also took place during this period. The average value from 2016 to 2021 from Figure 18 is used for the analysis: ࡱࢋൌ૚ǡ૜૞૜ǡ૙૛૞ܓ܅ܐ ܉ 5.1.3. Refrigeration No information is available on the amount of refrigeration consumed. The cooling system, which is located on the roof, consists of a cooling unit and condensers. These systems use electricity to cool the refrigerant, however this consumption is not measured separately. Since the data on total electricity consumption is available, a separate indication of electricity consumption for cooling is not absolutely necessary for the CO΍ calculation in this study. 1569,645 1553,573 1072,415 1216,465 1353,025 0 200 400 600 800 1000 1200 1400 1600 1800 Energy Certificate (2016 - 2018) 2019 2020 2021 Mean 2016 - 2021 MWh / Year Electricity consumption in MWh 53 Energy and CO΍ Analysis of the Building Figure 22 illustrates the progression of emissions and emission factors in the electricity sector of Germany between 1990 and the projected emission levels for 2022. Figure 22: Development of specific emissions of the German electricity mix 1990-2021 and first estimates 2022 (Translated from German) Source: UBA] As evident in Figure 22, emissions from electricity generation saw a significant decrease up to the year 2020. However, this trend did not continue into 2021 and 2022. Furthermore, there have been significant changes to the electricity generation industry in Germany in response to the conflict in Ukraine and the closure of the Nord Stream pipeline in September 2022 (Federal Network Agency, 2022). Based on Figure 23, coal-based electricity production witnessed an 8.4% increase between 2021 and 2022, accounting for a substantial one-third of total electricity production. Energy and CO΍ Analysis of the Building 54 Figure 23: Electricity fed in from conventional and renewable energy resources in percent Source: DeStatis, 2023 This surge has counteracted the notable reductions in electricity production from natural gas and nuclear energy, but it has also increased the emission factor. The tense situation in the gas market after the Ukraine conflict resulted in an 11.3% decline in electricity generation from natural gas. Nuclear power generation witnessed a 50% decrease in 2022 when compared to the previous year, as Germany's phased-out three out of six nuclear power plants. Simultaneously, the percentage of renewable energies grew by 7.3% to 46.3% as illustrated in Figure 23, thereby resulting in solar power production experiencing a remarkable 19.5% surge and now contributing to 10.6% of the overall electricity generation. In conclusion, the quantity of electricity imported from other countries into Germany diminished by 4.8% in 2022 as compared to 2021, with France displaying an incredible 62.0% drop in electricity export to Germany. (DeStatis, 2023). Given the highly variable emission factors in recent years, making predictions for subsequent years has become even more challenging. In this study, the CO΍ emission factors from the CRREM V2 Tool were used for the years 2020 to 2050. These factors seem to be based on scenarios that also account for the possibility of not achieving the decarbonisation of electrical grids. 55 Energy and CO΍ Analysis of the Building The trend in CO΍ consumption in electricity generation is presented as follows: Emissions decrease from 0.3387 kgCO΍/kWh to 0.051 kgCO΍/kWh, as depicted in Figure 24. Figure 24: Decarbonisation path of electricity according to CRREM V2, 2023 (own illustration). It is noticeable that the curve starts to flatten from 2040 onwards and remains constant from 2045. However, upon reviewing the CRREM documents, no justification for this stagnation was found. One can hypothesize that the most recent climate protection goals were not considered at the time of its creation, or that a more sceptical scenario was assumed. The electricity emission factor used in this analysis for the year 2020 is: ࡱࡲࢋൌ૙Ǥ૜૜ૡ૟૟ܓ܏۱۽૛ࢋ ܓ܅ܐ 5.2.3. Refrigeration In cooling systems, the emitted emissions are not CO΍ but rather a mixture of refrigerants, which also contribute to the greenhouse effect. These are commonly referred to as CO΍ Equivalents (CO΍e) and are quantified by a dimensionless metric known as the Global Warming Potential (GWP). A GWP of 1 indicates that 1 kilogram of the substance, when released into the atmosphere, has the same potential to contribute to global warming as 1 kilogram of CO΍ over a period of 100 years. 0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 2020 2025 2030 2035 2040 2045 2050 kgCO2/kWh Energy and CO΍ Analysis of the Building 56 The refrigerant R407C used in the building is a blend of three different refrigerants: R32, R125, and R134a. Each of these refrigerants has its own GWP value. To calculate the GWP of R407C, it is necessary to weight the GWP values of these individual refrigerants according to their proportion in the mixture, and then sum them up. The UBA listed the GWP values of various refrigerants in a 2021 study. The relevant data for R407C are as follows: x R32 (Difluormethan): GWP = 675 x R125 (Pentafluorethan): GWP = 3,500 x R134a (1,1,1,2-Tetrafluorethan): GWP = 1,430 The composition of R407C is 23% R32, 25% R125 and 52% R134a, as stated by the UBA in 2021. Based on this composition, the global warming potential (GWP) of R407C is calculated as follows: ܩܹܲோସ଴଻஼ൌͲǤʹ͵כܩܹܲோଷଶ ൅ͲǤʹͷכܩܹܲோଵଶହ ൅ͲǤͷʹכܩܹܲோଵଷସ௔ (1) It follows that: ܩܹܲோସ଴଻஼ൌͲǤʹ͵כ͸͹ͷ൅ͲǤʹͷכ͵ǡͷͲͲ൅ͲǤͷʹכͳǡͶ͵Ͳ The GWP used in this analysis is therefore: ࡳࢃࡼࡾ૝૙ૠ࡯ ൌ૚ǡૠૠ૜Ǥૡ૞۱۽૛܍ 5.2.4. Natural Gas The emission factor for natural gas in Germany is provided by the Federal Office of Economics and Export Control (BAFA). The most recent version was published in their Information Sheet on CO΍ Factors in May 2023 (BAFA, 2023). This analysis employs that emission factor. Therefore, the emission factor for natural gas used in this analysis is as follows: ࡱࡲ࢔ࢍ ൌ૙Ǥ૛૙૚ܓ܏۱۽૛܍ ܓ܅ܐ 5.2.5. Summary of Chapter 5.2 The chapter focuses on the evaluation of emission factors for various energy sources. Emission factors are measured in kgCO΍/kWh and serve as the baseline 57 Energy and CO΍ Analysis of the Building for calculating the building's current carbon footprint. For district heating, provided by Vattenfall, the emission factor has significantly improved due to Vattenfall's commitment to decarbonisation, aiming for a CO΍-free network by 2045. Electricity consumed in the building is assumed to be from the German electricity mix, which has seen a fluctuating emission factor due to geopolitical and environmental factors. Refrigeration systems use a blend of refrigerants with different Global Warming Potentials (GWP), calculated to be 1,773.85 CO΍e for the refrigerant R407C used in the building. Lastly, the emission factor for natural gas, a common energy source in Germany, is also discussed. The chapter sets the stage for achieving the EU Green Deal target of reducing emissions to zero kgCO΍/kWh in the building sector by 2050. 5.3. Overall Assessment In this section, the previously determined data on energy consumption and CO΍ emissions are placed in a broader context. The aim is to make a comprehensive assessment of the efficiency of the building under consideration. 5.3.1. Carbon Intensity Carbon intensity serves as a measure of the amount of greenhouse gases emitted per unit or service, directly or indirectly, by an activity, individual, or organization. This value is the focal point of this feasibility analysis because a building is considered decarbonized when its carbon intensity reaches zero. The United Nations Environment Programme (UNEP, 2009) calculates the carbon intensity of buildings in kgCO΍e/m²/a by multiplying energy consumption values by their corresponding emission coefficients and then normalizing these products to the building's gross floor area. An addition made in this Master's thesis involves the inclusion of greenhouse gases (GHGs) from refrigerants. Here, instead of multiplying the energy consumption by the emission factor, the refrigerant's leakage rate is multiplied by its Global Warming Potential (GWP) when taking it into account. The formula used to determine carbon intensity in this feasibility study is as follows: ܥܫ ൌͳ ܣே௘௧ ൫σܧ௜ൈܧܨ௜൅σܮ௝ൈܩܹܲ௝൯ (2) Energy and CO΍ Analysis of the Building 58 Where: ܥܫ: Carbon Intensity in kgCO΍e/m²/a ܣ௡௘௧ : Net Floor Area of the building in m² ܧ௜ : Energy consumption of the i-th energy source per year in kWh/a ܧܨ௜: Emission factor of the i-th energy source in kgCO΍e/kWh ܮ௝: Refrigerant loss of the j-th refrigerant per year in kg/a ܩܹܲ௝: Global Warming Potential of the j-th refrigerant (dimensionless) Using the values from the previous chapters in Formula 2, the total emission can be considered as part of the area ratio: ܥܫ ൌͳ ܣே௘௧ ൫ܧௗ௛ ൈܧܨௗ௛ ൅ܧ௘ൈܧܨ௘൅ܧ௡௚ ൈܧܨ௡௚ ൅ܮோସ଴଻஼ൈܩܹܲோସ଴଻஼൯ ܥܫ ൌͳ ͳͷǡͷͲͲʹ൬ͺͻǡ͹ͶʹǤ͹͵͸ͺ൅ͶͷͺǡʹͳͷǤͶͶ͸ͷ൅ͳͲǡ͵ʹͳǤͻͷ൅ͳͲǡ͸Ͷ͵Ǥͳሻଶ ൰ ܥܫൌͳ ͳͷǡͷͲͲଶ൬ሺͷ͸ͺǡͻʹͺǤ͸ͷ΍ ൰ And consequently indicate the carbon intensity: ࡯ࡵൌ૜૟Ǥૠܓ܏۱۽૛ ܉ ܕ; 5.3.2. Energy Use Intensity The energy use intensity (EUI) in kWh/m² is a benchmark for the total energy consumption of a building in relation to the gross floor area. It is a key metric used in the methodology to assess the energy efficiency of a building. ܧܷܫ௕ൌݐ݋ݐథ ܣ௚௙ Where: 59 Energy and CO΍ Analysis of the Building ܧܷܫ௕: Energy use intensity for the building ݐ݋ݐథ : Total average energy consumption for the building ܣ௚௙ : Gross floor area for the building Based on the given gross floor area of 15,550 m² from the energy certificate and the resulting total energy consumption per year of 3,018,455 MWh, the energy intensity can be determined as: ܧܷܫ௕ൌሺͳǡ͸ͳͶǡͲ͹ͺ൅ͳǡ͵ͷ͵ǡͲʹͷ൅ͷͳǡ͵ͷ͵ሻ ͳͷǡͷͲͲଶൌ͵ǡͲͳͺǡͶͷͷ ͳͷǡͷͲͲଶ follows: ࡱࢁࡵ࢈ൌ૚ૢ૝Ǥૠܓ܅ܐ ܕ૛ Energy-Saving Measures 60 6. Energy-Saving Measures In this chapter, the technical options for energy-saving measures in the hotel building were calculated. The findings on technical equipment, energy consumption, and emission factors from previous sections were utilized to determine the results. Table 9 presents a chronological summary of the energy-saving measures. Table 9: Summary of the necessary energy saving measures. Measure Description Type of saving Annually savings Annually CO΍/m² savings Implemen tation M1 Efficient lighting Electricity 198,881 kWh 4.35 2023 M2 PV-Roof KЇ from electricitygrid 26,934.5 kgKЇ 1.74 2025 M3 Refrigerant conversion KЇe 10,643 kgKЇe 0.69 2030 M4 Retrofitting HVAC Electricity and heating 152,686 kWh electricity + 48,362 kWh heat 4.64 2030 M5 AI-based HVAC control Electricity and heating 71,253 kWh electricity + 48,362 kWh heating 1.73 2034 The results from Table 9 were analysed and calculated in this chapter and subchapter. The results were entered into the created Excel tool in Chapter 7, which led to the development of the decarbonisation and energy intensity pathways. 6.1. M1 Lighting Two main factors primarily determine the energy consumption of lighting: the power of the light source in watts (W), and the duration of illumination in hours. Regarding the duration of illumination, significant reductions are achievable through the installation of motion and daylight sensors. These sensors are particularly effective in areas that are infrequently occupied, such as corridors or stairwells with natural light, which are common in the building under study. By utilizing these sensors, one can reduce both the duration and intensity of lighting. Figure 25 provides an illustration of the potential energy savings. 61 Energy-Saving Measures Figure 25: Analysis of energy consumptions with and without daylightand presence detectors (Source: Own illustration) Figure 25 compares the energy consumption for lighting without control systems to lighting equipped with sensors for daylight brightness and motion detection. The analysis found that the implementation of daylight utilization and presence detectors could potentially achieve an energy saving of 63%. Research in the field of lighting control systems (LCS) supports this estimate, demonstrating savings between 73 and 82% when using LCS and luminance sensors (Budhiyanto & Chiou, 2022). Although the study focused on a classroom setting, similar technologies and methods could be applied in hotel buildings to maintain visual comfort while simultaneously reducing energy consumption. Because the setting was a school, the results can't be directly transferred; therefore, the estimated saving of 63% is assumed. Additional savings can be achieved by replacing the existing lighting fixtures with LEDs. As described in "Analysis of Technical Building Systems for Energy Saving Options" in chapter 4.6.6, the building has different types of lighting sources, most of which are obsolete, such as halogen spotlights. In order to obtain as accurate an estimate as possible of the energy savings, the various types of lighting fixtures were counted during the building inspection and assigned to the respective areas. The corresponding power values were also recorded. The annual lighting duration for the different areas was estimated and optimisation measures applied. Table 10 shows the calculation factors and results. Energy-Saving Measures 62 Table 10: Energy consumption for lighting. Table 10 shows that the greatest energy savings can be achieved by replacing the halogen luminaires, as this is where the transition is most rewarding. In combination with the reduced lighting time, the largest saving of 88,844 kWh/a is made with the halogen luminaires in the corridors. Since the toilets are already equipped with sensors for person recognition, only 146 kWh/a can be saved in this area, it should be noted that the calculations assume the hotel building operates 24 hours a day, 7 days a week, particularly for reception and security areas. For other areas, the lighting duration has been reduced by 63% through the use of sensors, while the restrooms already feature motion sensors. The analysis also accounts for the transition to LED lighting, which can reduce the power requirements of traditional lighting sources by more than 75% (U.S. Department of Energy, no date). Areas where LEDs have already been installed are excluded from the calculations. The annual electricity consumption for lighting before the implementation of efficiency measures amounted to 288,570 kWh. After implementing the measures, this was reduced to 89,689 kWh. This corresponds to a savings of 198,881 or 68.92%. A plausibility check was conducted by comparing the building's total annual electricity consumption of 1,353,024 kWh with the consumption before the energysaving measures. The share of electricity consumption for lighting in the total consumption before the measure stands at approximately 21.3%, which is 4.4% higher than the figures for lighting in non-residential buildings as stated in the DENA Building Report 2023 (DENA, 2022). This deviation is considered plausible due to the building's 24/7 operation. Given the high potential for savings, it is assumed that this measure can be implemented in the short term. Are a Daily use h Days of operation Bulb type Power W (old) Power W (new) Qti Duration h (old) Duration h (new) Consump kWh (old) Consump kWh (old) Diff. kWh Hotel Room 3365 Light Strips 36 25 900 1.095 690 35.478 15.522 19.956 8208 Halogen 205 35 130 1.664 1.048 44.346 4.770 39.576 8208 Halogen 208 94 70 1.664 1.048 24.228 6.898 17.330 Reception 24 365 Halogen 105 18 20 8.760 8.760 18.396 3.154 15.242 2365 Light Strips 55 30 35 730 730 1.405 767 639 2365 Halogen 20 10 20 730 730 292 146 146 Corridors 24 365 Halogen 26 12 550 8.760 5.519 125.268 36.424 88.844 Kitchen 12 365 Halogen 108 75 55 4.380 4.380 26.017 18.068 7.950 Safety Light 24 365 Unknown 10 3150 8.760 8.760 13.140 3.942 9.198 Conference Room Toilette 69 Energy-Saving Measures lowest savings, at 0.7 kgCO΍/m²/a, come from transitioning to a climate-neutral refrigerant. 6.7. Non-considered measures The measures presented in this section are generally feasible and offer some significant potential for savings. However, their implementation in the sample building is currently difficult or not feasible altogether. The section aims to provide clarity as to why not all standard energy-saving measures have been calculated. 6.7.1. Retrofit Insulation Retrofitting the building envelope offers significant energy-saving potential, especially in old buildings that still retain their original exterior walls. However, due to the building's historical and cultural significance, it is under special protection for heritage preservation. Consequently, alterations affecting its external appearance are either not permissible or require substantial effort. For this reason, this study will not consider measures related to the building envelope. To still provide an assessment of the potential for renovating the building envelope, Figure 27 compares the existing U-values according to the thermal insulation certificate (confidential) of the current building with the values of the current legal minimum standard. Energy-Saving Measures 70 Figure 27: U-values of building parts A to D compared with U-value according to minimum requirements (own illustration) The Figure 27 reveals that the exterior walls of building sections A to C would offer tremendous energy-saving opportunities. Since the windows have already been replaced and the roof has been insulated from the inside, the savings in those areas are relatively low. The Figure 27 clearly indicates that, notably, the exterior walls of building sections A to C offer significant energy-saving opportunities. Since the windows have already been replaced and insulation has been added to the interior of the roof, the potential for energy savings in these areas is comparatively low. 6.7.2. Hydraulic Balancing and Replacement of Pumps Hydraulic balancing is a technique aimed at optimizing the water flow in heating and cooling systems within buildings. The objective is to adjust the distribution of the heating or cooling fluid (usually water) in such a way that it uniformly supplies all radiators or cooling surfaces within the structure. Energy savings are achieved through more efficient pump performance and a more even distribution of heat throughout the building (EU.BAC, 2021). *Minimum requirements for refurbishment according to the German Building Energy Act (GEG). **Average U-value formed from the different heat transfer coefficients and the area proportion of the different exterior wall types for building section 4, estimated value according to building age class for the exterior wall of building sections 1-3. *** This is an aluminium frame mullion and transom façade with insulating glazing. A - C D 71 Energy-Saving Measures Due to the building's cooling being almost entirely dependent on the ventilation systems, and approximately 45% of the heating also being channelled through these systems, the savings from fluid distribution are minimal. Moreover, the building was equipped with high-efficiency pumps in 2016, which also marginally impacts the efficiency of pump performance. For these reasons, this study will not delve into this measure. Results 72 7. Results In this study, various energy-saving measures (referred to as M1 to M5) for heat, electricity, and CO΍ consumption have been evaluated. These measures have been integrated into a CRREM-based Excel tool, which already takes into account the decarbonisation paths for electricity and heating networks. For the analysis, two graphs were created covering the timeframe from 2020 to 2050. The first graph visualizes the building's decarbonisation path, expressed in kgCO΍/m²/a. The second graph displays the building's energy intensity, measured in kWh/m²/a. Together, these two graphs form the climate protection plan for the studied hotel building. The use of the CRREM V2 tool allowed the integration of European climate protection targets into the analysis, thereby assessing whether the building meets legal requirements with the implementation of appropriate energy-saving measures or if there exists a stranding risk for the property. The analysis results appear in Figures 28 and 29, showing the CO΍ intensity and the building's energy intensity, thereby providing a holistic view of the effects of the implemented saving measures. Additionally, a sensitivity analysis was conducted to identify the most significant influences and factors on the decarbonisation effect. For this purpose, four scenarios (Figure 30 to 33) were created. They show the building's paths without measures and with emission factors for electricity and heat according to CRREM, both with and without regional emission factors. Results 73 Figure 28: Decarbonisation path 2020 to 2050 for the analysed hotel building based on CRREM V2 (own illustration) M1 M3 & M4 M5 M2 Results 74 Figure 29: Energy intensity path 2020 to 2050 for the analysed hotel building based on CRREM V2 (own illustration) M1 M3 & M4 M2 M5 75 Results From Figure 28, it is apparent that the building's CO΍ emissions are initially far below the decarbonisation path at the beginning of the observation period. In 2020, the target path is at 60.3 kgCO΍/m²/a, whereas the building only shows 36.7 kgCO΍/m²/a. Through measures M1 to M5, the building continues to reduce its CO΍ consumption until 2034. At this point, the total emission consumption exceeds the decarbonisation path with 12.4 kg/CO΍/m²/a, with a surplus of 0.82 kg/CO΍/m²/a, indicating a stranding risk for the building. The highest difference amounts to about 4 kgCO΍/m²/a in year 2039, constituting an excess of 84%. Due to further reductions in the carbon budget through the decarbonisation of electricity and heating networks, as well as the annual savings from the photovoltaic modules, the building is around 2.8 kgCO΍/m²/a above the requirements by 2050. This excess is due to 2.74 kgCO΍/m²/a emissions from electricity consumption and 0.67 kg/CO΍/m²/a of natural gas. As with the decarbonisation path, Figure 29 initially shows an energy intensity of 194.7 kWh/m²/a, approximately 25.3 kWh/m²/a below the required value. However, the lines intersect at 173 kWh/m²/a after measure M1 in 2024, meaning the building has a higher energy index than the benchmark value of taken from the CRREM tool. Energy-saving measures M2 and M3 do save CO΍ but do not affect the building's energy behaviour as neither the photovoltaic modules nor the refrigerant replacement reduces energy consumption. Only the replacement of the HVAC systems (M4) significantly reduces the energy requirement for electricity and heat to 148.7 kWh/m²/a, yet it still doesn't meet the requirement values of 120.7 kWh/m²/a. Likewise, measure M5 noticeably reduces the kWh/m²/a but still not enough to fall below the 95 kWh/m²/a assumed from 2035 onwards. Overall, the building's energy intensity is reduced to 131 kWh/m²/a by 2050, which is 37.9% above the benchmark. Contrary to the decarbonisation path, a stranding risk cannot be immediately assumed in this case, as there are currently no legal requirements for the energy intensity of a non-residential buildings already described in chapter 2. However, it does provide a good comparative and benchmark value to keep pace with future requirements. Results 76 In summary, the CO΍ emissions can be reduced by a total of 32.9 kg per m² and year which represents a reduction of 90%. The energy consumption was reduced by 53.8 kWh per year and m², which corresponds to a saving of 28%. However, the building does not manage to operate completely climate-neutral nor achieve the proposed energy efficiency with the suggested measures. Results 77 Sensitivity Analysis Figure 30: Decarbonisation path without measures, with district heating emission factor according to CRREM. Figure 31: Decarbonisation path with measures, with district heating emission factor according to CRREM. Figure 32: Decarbonisation path without measures, with district heating emission factor from energy provider. Figure 33:Decarbonisation path with measures, with district heating emission factor from energy provider (used in the study). Results 78 The sensitivity analysis clearly indicates that the emission factors for district heating play a crucial role in determining whether the building can maintain its decarbonisation trajectory. This becomes evident when comparing Figure 30, which utilizes the emission factors from the CRREM V2 Risk Assessment Tool, with Figure 32 that employs regional emission factors as used in the study. Neither of these figures takes energy-saving measures into account. Even with the implemented measures, the building would not meet the target guidelines for average emission factors for district heating. Figure 31 makes this clear, showing the building's trajectory above the target path, even when taking energy-saving opportunities into account. A partially achievable path exists only when considering the regional emission factor and only if it is significantly lower than CRREM V2's average factor or the one determined by UBA. This conclusion stems from Figures 32 and 33. The study did not further analyse the electricity emission factor since the building does not utilize green energy. It would also be interesting to determine the target achievement values if a switch to renewable energy sources emitting little to no CO2 were made. In conclusion, predefined and regionally varying emission factors for energy supply networks and their projections up to 2050 play a pivotal role in achieving CO2 neutrality. While energy-efficient measures cannot prevent stranding risks, they can at least delay them. 85 References Energy Information Administration (eia), 2017. eia.gov, consumption. [Online] Available at: https://www.eia.gov/consumption/commercial/reports/2012/lighting/ [Accessed 24 August 2023]. EU.BAC (European Building Automation and Controls Association), 2021. System Balancing for Technical Building Systems: a great opportunity for Energy Savings and Comfort, Brussels: s.n. European Comission, 2019. eur-lex.europa, Legal content. [Online] Available at: https://eur-lex.europa.eu/legalcontent/EN/TXT/HTML/?uri=CELEX:52019DC0640 [Accessed 16 August 2023]. 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Appendices Appendices Appendices A0:Cooling schemes from time of the reconstruction in 2003«a Appendices A1: Extract form the technical inventory, protected heritage«...b Appendices A2: Differences normalisation««««««««««.«««««F Appendices A3: Extract from DIN 4710 for the specification of ventilation degree hours in Berlin«««««««««««««««««««««««««G Appendices A4: Data sheet PV Module Solarwatt«««...«««««««««H Appendices A5: Data sheet SMA inverter««««««««««««««««I b Appendices Appendices A0: Cooling schemes from the time of the reconstruction in 2003 Appendices c Appendices A1: Extract form the technical inventory, protected heritage d Appendices Appendices A2: Differences normalisation Figure 34 With normalisation Figure 35 Without normalisation Graphical illustration of the normalisation due to HDD/CDD. Without normalisation, the calculation of the GHG intensity amounts to 10.90 kg/CO΍/m² and with normalisation to 10.56 in 2050. This means that the exemplary building must consume approx. 3.2 % less CO΍ to avoid stranding. The calculation is an example for estimating the HDD/CDD impact.