u .oekom.de h ps://doi.o g/10.14512/ u .1655
BEITRAG ARTICLE OPEN ACCESS
Making land a ailable. Cul u al legal compa ison o he
Ge man Building Land Mobilisa ion Ac and he pa ial
e ision o he Swiss Spa ial Planning Ac
And eas Hengs e mann , Nadja Skala
Recei ed: 2 Augus 2022 Accep ed: 10 Janua y 2023 Published online: 14 Feb ua y 2023
Abs ac
Planning p ac ice is con on ed wi h seemingly con adic o y
challenges, such as he quali a i e and quan i a i e p o i-
sion o housing pai ed wi h educing land consump ion. To
add ess his appa en dilemma, legisla o s a e inc easingly
elying on densi ica ion. Howe e , a undamen al p e equisi e
(and o en a signi ican challenge) o his is he a ailabili y
o he land equi ed. Recen planning law e o ms in Ge many
and Swi ze land aim o inc ease he e ec i eness and speed
a which land is made a ailable o inne de elopmen , hus
mee ing he seemingly con lic ing planning policy goals. This
pape compa es ecen legisla i e e o s in Ge many and
Swi ze land using he compa a i e law me hod. The Ge man
Building Land Mobiliza ion Ac includes amendmen s o he
Building Code (Baugese zbuch)and heBuildingUseO di-
nance (Baunu zungs e o dnung), in ended o enable as e
ac i a ion o building land and he c ea ion o mo e a o d-
able housing. To his end, he amendmen expands exis ing
ins umen s o he ac i a iono building landand in oduces
simpli ica ions o he planning law. In Swi ze land, he Spa ial
PlanningAc hasbeenpa ially e ised oachie einne u ban
de elopmen h ough p ecise egula ions on he expansiono
D . And eas Hengs e mann, Uls e Uni e si y, Sho e Road,
Jo dans own Campus, BT37 0QB Bel as , UK
a.hengs e mann@uls e .ac.uk
Nadja Skala, Ha enCi y Uni e si ä Hambu g, Henning-Vosche au-
Pla z 1, 20457 Hambu g, Ge many
nadja.skala@hcu-hambu g.de
© 2023 by he au ho (s); licensee oekom. This Open
Access a icle is published unde a C ea i e Commons A ibu ion
4.0 In e na ional Licence (CC BY).
buildingzonesandins umen s oensu e heimplemen a ion
o zoning plans.
Keywo ds: Planning Law legal inno a ions use and
disposal igh s cul u al legal compa ison
Flächen mobilisie en. Ein kul u elle
Rech s e gleich des deu schen
Baulandmobilisie ungsgese zes und de
Teil e ision des schweize ischen
Raumplanungsgese zes
Zusammen assung
Die plane ische P axis is mi scheinba wide sp üchlichen
planungspoli ischen He aus o de ungen kon on ie , wie
beispielsweisedie quali a i e und quan i a i e Be ei s ellung
on Wohn aum bei gleichzei ige Reduk ion de Flächenin-
ansp uchnahme. Um dem scheinba en Dilemma zu begeg-
nen, se z de Gese zgebe zunehmend au Ve dich ung. Eine
G und o ausse zung (und häu ig g oße He aus o de ung) da-
ü is jedoch die a sächliche Ve ügba kei de benö ig en
Flächen. Jüngs e Re o men des Planungs ech s zielen sowohl
inDeu schlandalsauchinde Schweizda au ebendieseBau-
land e ügba kei zu ö de n, um so die benö ig en Flächen
ü die Innenen wicklung e ek i e und schnelle e ügba
zu machen, um den scheinba kon ä en planungspoli ischen
Zielen zu en sp echen. Diese Bei ag e gleich die jüngs-
en gese zgebe ischen Bemühungen in Deu schland und de
Schweiz mi Hil e de Me hode de Rech s e gleichung. Das
deu sche Gese z zu Mobilisie ung on Bauland (Baulandmo-
bilisie ungsgese z) en häl Ände ungen des Baugese zbuchs
und de Baunu zungs e o dnung, die eine schnelle e Ak i ie-
ung on Bauland und die Scha ung on meh bezahlba em
Wohn aume möglichensollen.Dazuwe dendiebes ehenden
Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604 591
A. Hengs e mann,N. Skala
Ins umen e zu Baulandak i ie ung e wei e und planungs-
ech liche Ve ein achungen einge üh . In de Schweiz wu de
das Raumplanungsgese z eil e idie , um eine Siedlungs-
en wicklung nach innen du ch p äzise Regulie ungen bei de
Auswei ungde BauzonesowieIns umen ezu Siche s ellung
de a sächlichen Umse zung de Nu zungszonenplanung zu
e wi ken.
Schlüsselwö e : Planungs ech Rech sneue ungen 
Nu zungs- und Ve ügungs ech e Kul u elle Rech s e gleich
1 Housing supply and educing land
ake: An os ensible con adic ion
Planning p ac ice is con on ed wi h seemingly con adic-
o y planning policy challenges. On he one hand, he is-
sue o housing p o ision has once again become u gen
in many coun ies, bo h in e ms o gene al, quan i a i e
p o ision o housing in ce ain egions (e.g. in me opoli-
an a eas) and in e ms o qualified p o ision (e.g. in e ms
o housing affo dabili y) (Deb unne /Hengs e mann/Ge be
2020). On he o he hand, con olling he ongoing sealing
o g een spaces is a adi ional and mo e p essing planning
challenge o comba clima e change. Rega dless o he ex-
ac defini ion and conc e e measu emen o his new land
ake (Jaege /Schwick 2014; Deco ille/Schneide 2016;Ba -
bosa/Vallecillo/Ba anzelli e al. 2017; Ma on/B ownlie/Bull
e al. 2018; Ma qua d/Ba ke/Gi eu i Fon e al. 2020), i
should be no ed ha a educ ion o ‘ne ze o’ includes bo h
he p o ec ion o g een spaces and he ac i a ion o inne
de elopmen po en ials.
The Eu opean Union (Hennig/Schwick/Soukup e al.
2015; V ebos e al. 2017) and also some Membe S a es
ha e added (mo e o less) conc e e legal objec i es o hei
policy goals in his ega d (Scha z/Bo e /Liede e al. 2021),
such as Belgium (Halleux/Ma cinczak/ an de K abben
2012; Bui elaa /Lein elde 2020), F ance (Jehling/Hech
2022), Aus ia (Meinel/Schumache /Behnisch e al. 2019;
Kanonie 2020), Poland (S ache zak/Hełdak/Hájek e al.
2019) and he Czech Republic (Vejchodská/Pelucha 2019).
The opic is also es ablished as a poli ical issue in Ge -
many and Swi ze land. In i s sus ainabili y s a egy, Ge -
many s a ed ha new daily land ake should be educed om
120 ha o 30 ha (Bundes egie ung 2002: 99). Effec i ely, i
has been possible o educe land ake ( o abou 55 ha pe
day),1bu he o iginal a ge has been pos poned om 2020
o 2030. In addi ion, he e a e demands o implemen ne -
1h ps://www.des a is.de/ans ieg-su .h ml (30.12.2022).
ze o ake-up by 2050, e.g. by he Eu opean Commission,
he Ge man Council o Sus ainable De elopmen (RNE),
he Ge man Council o En i onmen al Ad iso s (SRU) and
he Na u e and Biodi e si y Conse a ion Union (NABU).
A he same ime, he e is a c oss-pa y adi ion o p o-
mo ing housing, mos ecen ly he 400,000 housing a ge
o he cu en go e nmen (Bundes egie ung 2021: 88). In
Swi ze land, he o igin o spa ial planning lies in p o ec ing
ag a ian landscapes (G iffel 2017b: 21). In ecen imes,
legisla o s ha e also come unde p essu e o inc ease he e -
ec i eness o spa ial planning om a ious popula ini ia-
i es (Hengs e mann/Ge be 2015; Aemisegge /Moo /Ruch
e al. 2016a), such as he “Landscape Ini ia i e” (2008),
he “Second Homes Ini ia i e” (2012), he “U ban Sp awl
Ini ia i e” (2019) and cu en ly he “New Landscape Ini-
ia i e” (pending). While affo dabili y is a ocus, he e is
also a poli ical effo o p omo e he p o ision o housing
in gene al.
Wha all app oaches ha e in common is ha expand-
ing housing supply while economising on land ake cons i-
u es an appa en dilemma. This, howe e , can be esol ed
h ough dense cons uc ion and consis en inne de elop-
men . The g ea es challenge o such a s a egy is, again,
accessing he equi ed land, he a ailabili y o which is de-
e mined by he buildabili y o an a ea in planning and legal
e ms, and he willingness o he landowne s o build. The
logic o plan-led planning is based on he ac ha capi-
alisa ion o he land en encou ages building. While he
mechanism wo ks in he as majo i y o cases, in indi id-
ual cases i can be seen ha e en in economically a ac-
i e loca ions some o he sui able land emains effec i ely
una ailable o building de elopmen . Ce ain owne s e-
sis he economic added alue o building de elopmen and
lea e hei land unde used o unused, despi e i being desig-
na ed as sui able o de elopmen (Colsae /Lau ans/Le el
2018; Bo icini/Auzins/Lacoe e e al. 2022). In e ms o he
plan-led planning sys em, owne s hus ha e a e o posi ion
in he implemen a ion o land-use planning, which coun e -
ac s he inc easing pe o mance-based o ien a ion o spa ial
planning (Ge be 2016). Only i he landowne s become ac-
i e h ough building o selling hei p ope y is he plan’s
ac ual implemen a ion possible.
Imp o ing building land a ailabili y is called he mobili-
sa ion o building land. This can be achie ed bo h h ough
a p ope y’s legal s a us as a buildable a ea and by inc eas-
ing he willingness o p ope y owne s o build (o hei
willingness o sell o owne s willing o build).
Recen – and in pa inno a i e – e o ms o planning
law in a ious coun ies aim o inc ease he a ailabili y o
building land, making he land necessa y o inne de el-
opmen a ailable mo e effec i ely and quickly. The seem-
ingly con adic o y planning policy goals ( educing land
592 Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604
Making land a ailable. Cul u al legal compa ison o he Ge man Building Land Mobilisa ion Ac and he pa ial ...
ake and p o iding housing) a e hus econciled h ough
effec i e planning and dense cons uc ion. In legal heo y,
his means ha he ac ions o public au ho i ies egula e he
igh s o use land, while he igh s o dispose o land a e o
be influenced by public policy.
The s uc u e o his pape ollows ou me hodological
app oach (as desc ibed in Sec ion 3). Sec ion 1has al eady
ou lined he subs an i e p oblem in he wo selec ed coun-
ies. Sec ion 2explains he co esponding legal- heo e i-
cal backg ound. Sec ion 3explains he me hodological ap-
p oach using cul u al compa a i e law. Sec ions 4and 5
show he mos ecen egula o y changes made by he e-
spec i e na ional legisla o s. Finally, a sys ema ic legal com-
pa ison is unde aken in Sec ion 6.
2 Gaps and u ban sp awl as
a challenge o planning
In legal e ms, land is a commodified good (Da y 1996;
Ge be /Ge be 2017). Acco dingly, p ope y is no a legal
ela ionship be ween a pe son and a hing bu a iangula
legal ela ionship be ween diffe en pe sons, which in u n
is p o ec ed by s a e ins i u ions (B omley 1992: 15). The
legal ela ionship consis s o se e al elemen s, me apho i-
cally called “bundles o igh s” (Demse z 1974: 163). The
exac classifica ion o hese bundles depends on he con ex
(Thiel 2008;Slae 2016).
Acco ding o B acke (2004), howe e , a simplified dis-
inc ion can be made be ween he igh s o disposal and he
igh s o use. Righ s o disposal include igh s ha in ol e
a ans e o he objec (e.g. p o isions on sale, pu chase,
en al, leasing, inhe i ance). Lending is also classified as
a igh o disposal. The igh s o disposal a e de e mined
by public and p i a e law. The igh s o use comp ise he
igh s ha de e mine and limi he manne o use o he
objec . This includes, in pa icula , how he p ope y can be
used wi hin he legal amewo k, as de e mined by public
law. Fo his pu pose, subs an i e and es ic i e p o isions
a e enac ed. In addi ion, he e a e easemen s ( igh s o way,
pipeline and access igh s) which, howe e , play a subo di-
na e ole. These can also be designed as conc e e indi idual
ag eemen s o gene al abs ac egula ions.
Spa ial planning is adi ionally land-use planning ha
ac s passi ely by egula ing igh s o use (Da y 1999;
Ha mann/Spi 2015). The cen al planning ques ion has
emained unchanged since on Jus i’s ime: “I is essen ial
o he s a e ha he immo able asse s, and in gene al he
land o he coun y, a e used in he bes possible way” ( on
Jus i 1760; in: Da y 1996: 194). Acco dingly, he pu pose
o planning p ocedu es is o de e mine he bes possible
use – and hus he legal egula ion o igh s o use, e.g. by
de e mining he ype and ex en o pe missible building use
wi hin he amewo k o binding u ban land-use planning
(zoning plan) in he o m o plan-led planning.
Issues conce ning he bes possible land dis ibu ion a e
called land e o m issues, Effec i ely, hey a e ha dly egu-
la ed in building and planning law. Some land managemen
ins umen s se e o esol e p oblems ha a ise om con-
adic o y si ua ions wi hin use and disposal igh s. Fo ex-
ample, (public) land eadjus men ensu es he alignmen o
he plo layou wi h he planning specifica ions o enable he
plan’s ealisa ion (Da y 2007). Building obliga ions (Heng-
s e mann 2017; Hengs e mann/Ge be 2017), g ound land
leases (Ge be /Nah a h/Ha mann 2017) and u ban exp o-
p ia ion/ egula o y akings (Al e man 2010) ha e a simila
effec , e en hough hese ins umen s a e discussed mo e
widely in planning heo y han hey a e used in planning
p ac ice.
Spa ial planning as land-use planning ac s acco ding o
land-use law, which allows de elopmen s o be amed and
undesi able effec s p e en ed. S ill, he gua an ee o plan im-
plemen a ion emains wi h he owne s. In poli ical science,
his is e e ed o as an incohe en egime (Nah a h 2003:
397), as con adic ions can a ise be ween he le els o igh s
o use and igh s o disposal. As a ule, his limi on possible
con ol does no pose a p oblem as long as he public in e -
es s a e la gely cong uen wi h he in e es s o he p i a e
landowne and he (p ima ily economic) incen i es o build-
ing on an a ea lead o i s ac ual use. In indi idual cases, in-
di idual p ope y igh s may ne e heless lead o a eas sui -
able o planning being deemed buildable unde building
law bu hen no being physically buil o e (Blomley 2017;
Jacobs/Paulsen 2009). Despi e he incen i e (capi alisa ion
o land p ices), he e is no exploi a ion because he own-
e s pu sue o he , non-economic goals. The possibili ies o
planning au ho i ies o ensu e he ac ual a ailabili y o land
a e ypically limi ed in such cases. Agains his backg ound
o planning and legal heo y, his a icle’s cen al ques ion
conce ns he ins umen s o u ilisa ion and disposal law ha
legisla o s in Ge many and Swi ze land a e ying o use o
p omo e he mobilisa ion o building land.
3 Cul u al legal compa ison
This pape is based on he app oach o so-called cul u al
compa a i e law (Zweige /Kö z 1998). Compa a i e law
ela es diffe en legal solu ions o a a ie y o simila p ob-
lems in o de o enable eflec ion on legal p ac ice, and,
i necessa y, o acili a e he ecep ion (Kunz 2006: 39) o
ansplan ing (Wa son 1974) o legal solu ions om else-
whe e. A dis inc ion is made be ween unc ional and cul-
u al legal compa isons. While unc ional legal compa isons
Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604 593
A. Hengs e mann,N. Skala
a e desc ip i e and use pu e knowledge o o eign law o
iden i y possible effec s on domes ic subjec s, cul u al le-
gal compa isons ollow he app oach ha na ional law is
an exp ession and mani es a ion o he cul u e o a socie y
(Michaels 2012). Acco dingly, he analysis o law ocuses
on he unde lying mechanism o impac – also called men al-
i y – and is he e o e no limi ed o a na ow in e p e a ion
o he legal ex (black le e law).
Following he app oach o cul u al compa a i e law,
he analysis comp ises h ee essen ial s eps (Zweige /Kö z
1998). Fi s ly, defining he subs an i e p oblem ha was he
poli ical igge and is o be sol ed p ima ily by he legal
sys ems. Secondly, iden i ying he egula ions in na ional
law ha a e in ended o sol e he poli ically subs an i e
p oblem p e iously defined. Thi dly, compa ing he ules,
i.e. an elabo a ion o unc ional diffe ences and he de el-
opmen o a sys em.
The esul s ob ained in he con ex o cul u al compa -
a i e law a e no only in e es ing om a compa a i e law
pe spec i e. Ra he he a icle’s me hodology also enables
legal p ac i ione s and decision-make s in many coun ies o
sha pen hei iew o legisla i e effo s o mobilise building
land and c ea e compac se lemen s uc u es.
4 Ge man Building Land Mobilisa ion
Ac (2021)
A e decades o con o e sial land policies, he Building
Land Mobilisa ion Ac 2is an a emp o acili a e he p o-
ision o building land as a cen al p e equisi e o hous-
ing cons uc ion and o push o physical cons uc ion o
coun e ac he exis ing housing sho age. The decisi e ac-
o was he go e nmen ’s coali ion ag eemen o 12 Ma ch
2018, in which he coali ion pa ies ag eed o suppo mu-
nicipali ies o ac i a e building land and secu e affo dable
housing (Bundes egie ung 2018: 109). Acco dingly, wi hin
he amewo k o he Housing Summi on 21 Sep embe
2018, wi h app oxima ely 120 pa icipan s om all 16 ed-
e al s a es, a ious measu es o in ensi y housing cons uc-
ion and imp o e housing affo dabili y we e de e mined,
and, as a esul , a join housing offensi e was adop ed by
he ede al go e nmen , he ede al s a es and he munici-
pali ies. In addi ion, an expe commission o sus ainable
building land mobilisa ion and land policy (Baulandkom-
mission) was es ablished o deal wi h his issue in dep h
(B eue 2022: 585). Membe s o he commission we e ep-
esen a i es o he go e nmen ac ions, he s a es, he mu-
2Gese z zu Mobilisie ung on Bauland (Baulandmobilisie ungs-
gese z) om 14. Juni 2021 (BauMobG).
nicipal umb ella o ganisa ions, housing and u ban de el-
opmen policy associa ions, ade unions and cons uc ion
indus y associa ions, as well as expe s om academia and
municipal p ac ice.3On 2 July 2019, he commission p e-
sen ed i s ecommenda ions, which became he basis o he
d a bill o 9 June 2020 o changing he Building Code4
and he Building Use O dinance.5These amendmen s a e
collec i ely e e ed o as he Building Land Mobilisa ion
Ac , which came in o o ce on 23 June 2021.
4.1 Re o m’s con ex
In he a ea o public building law, he legisla i e compe-
ence lies wi h he s a es, inso a as he Ge man Cons i-
u ion6does no exp essly assign legisla i e powe s o he
ede al go e nmen (A . 30 GG, A . 70 GG). Fo a eas
o concu en legisla ion, he s a es ha e he powe o enac
laws only as long as and inso a as he ede a ion has no
made use o i s compe ence by means o laws (A . 72 Pa a.
1 GG). Unde A icle 74 Pa ag aphs 1 and 18 o he Cons i-
u ion, his also applies o he a ea o planning law. He e, he
ede al go e nmen has used i s legisla i e compe ence by
enac ing he Building Code (BauGB) and legal o dinances
based on i (BauNVO and o he s), hus p o iding he munic-
ipali ies wi h a legal basis o egula ing land use. Wi hin he
esul ing legal amewo k, howe e , he municipali ies ha e
he igh o egula e all ma e s o he local communi y hem-
sel es (A . 28 Pa a 2 o he Ge man Cons i u ion). Wi h
he enac men o he Baulandmobilisie ungsgese z, he ed-
e al go e nmen in ended o s eng hen he municipali ies’
scope o ac ion ega ding he c ea ion o housing.
Ge man planning law dis inguishes be ween h ee a eas
in which buildings can be cons uc ed: he ( ully o pa -
ially) planned a ea (§30 BauGB), he unplanned inne a ea
(§34 BauGB) and he unplanned ou e a ea (§35 BauGB).
A clea dis inc ion mus be made be ween he diffe en un-
planned a eas, as he inne a ea may be buil upon unde
3h ps://www.bmi.bund.de/Sha edDocs/p essemi eilungen/
DE/2018/11/baulandkommission.h ml(02.01.2023).
4Baugese zbuch (BauGB) in de Fassung de Bekann machung
om 3. No embe 2017 (BGBl. I S. 3634), das du ch A ikel 2 des
Gese zes om 4. Janua 2023 (BGBl. I N . 6) geände wo den is .
5Baunu zungs e o dnung (BauNVO) in de Fassung de Bekann -
machung om21. No embe 2017(BGBl. IS. 3786), diedu chA ikel
3 des Gese zes om 4. Janua 2023 (BGBl. I N . 6) geände wo den
is .
6G undgese z ü die Bundes epublik Deu schland (GG) in de
im Bundesgese zbla Teil III, Gliede ungsnumme 100-1, e ö -
en lich en be einig en Fassung, das zule z du ch A ikel 1 des
Gese zes om 19. Dezembe 2022 (BGBl. I S. 2478) geände wo den
is .
594 Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604
Making land a ailable. Cul u al legal compa ison o he Ge man Building Land Mobilisa ion Ac and he pa ial ...
ce ain condi ions while he ou e a ea is o be kep ee o
any building de elopmen as a ma e o p inciple.
The amendmen s o he Baulandmobilisie ungsgese z a e
in ended, on he one hand, o c ea e oppo uni ies o make
land a ailable o housing cons uc ion mo e quickly o e -
ficien ly, e.g. by ex ending he possibili ies o exemp ion
om de elopmen plans and making i easie o build in
inne and ou e a eas. On he o he hand, he de elopmen
o p e iously unused a eas is o be p omo ed. This is done
p ima ily by expanding he scope o he applica ion o mu-
nicipal p e-emp ion igh s and he building o de o a eas
wi h igh housing ma ke s.
Some o he amendmen s in he Baulandmobilisie ungs-
gese z aim o acili a e o accele a e he possibili y o build-
ing and hus ha e an effec a he usage igh s le el. O he
egula ions, howe e , a e in ended o p omo e physical con-
s uc ion and hus ha e affec disposal igh s. The mos
impo an inno a ions o he Baulandmobilisie ungsgese z
– diffe en ia ed acco ding o hei effec le el – a e p e-
sen ed below.
4.2 Componen s a ec ing he usage igh s
le el
The ollowing inno a ions conce n bo h he planned and
unplanned inne a ea as well as he unplanned ou e a ea
and a e in ended o make i easie o mobilise building land.
4.2.1 U ban de elopmen concep o s eng hen inne
de elopmen (§176a BauGB)
The in oduc ion o §176a BauGB is in ended o make i
easie o municipali ies o use municipal a eas wi h dis-
pe sed and unde eloped b ownfield si es o cons uc ion
pu poses. The aim is o make i easie o u ilise land o
housing. Howe e , he p epa a ion o such a de elopmen
concep does no ha e a di ec ex e nal effec on p ope y
owne s o o he pe sons bu is a he in ended o jus i y
he necessi y o u ban de elopmen planning and measu es
(Rixne /Dü sch 2022: 1306).
4.2.2 Exemp ions om he land-use plan in a ou o
housing de elopmen (§31 pa a. 3 BauGB)
§31 BauGB offe s a municipali y he possibili y o making
excep ions and exemp ions om he land-use plan. Wi h
he new §31 pa a. 3 BauGB, a u he case o exemp ion in
a ou o housing cons uc ion was included in he Building
Code. Fo his exemp ion o apply a all, he p ojec mus be
loca ed in an a ea wi h a igh housing ma ke and mus be
designa ed as such by a co esponding legal o dinance o
he s a e go e nmen acco ding o §201a BauGB (Cha lie
2022: 436). An a ea is defined as a igh housing ma ke i
he e is a isk ha he popula ion in a municipali y o pa
o a municipali y canno be supplied wi h en al housing on
easonable e ms (§201a BauGB). The egula ion is limi ed
un il 31 Decembe 2026. Acco ding o his p o ision, an
exemp ion is also possible in indi idual cases i he basic
p inciples o planning a e affec ed (Cha lie 2022: 431).
This inno a ion hus opens up he possibili y o c ea ing
housing unde ce ain condi ions on land p e iously no
in ended o housing cons uc ion.
In addi ion o his egula ion, u he inno a ions acili-
a e he app o al o esiden ial cons uc ion p ojec s in in-
di idual cases. Fo example, he “ esiden ial needs o he
popula ion” a e now explici ly ci ed as being o public in-
e es and g ounds o exemp ions om he p o isions o
he land-use plan (§31 pa a. 2 no. 1 BauGB). Fu he mo e,
in he case o he cons uc ion o buildings o esiden ial
pu poses i is now possible no only o de ia e om he e-
qui emen o fi ing in o he cha ac e o he immedia e su -
oundings in indi idual cases, bu also in a numbe o com-
pa able cases (§34 pa a. 3a BauGB). Finally, he amended
§35 BauGB con ains u he modifica ions in ended o sim-
pli y he c ea ion o esiden ial space in ou lying a eas.
4.2.3 In oduc ion o a new sec o al land-use plan
ype o (social) housing (§9 pa a. 2d BauGB)
This sec o al land-use plan o he p o ision o housing,
newly in oduced by he Baulandmobilisie ungsgese z (§9
pa a. 2d BauGB), is in ended o p omo e he c ea ion o sub-
sidised housing, pa icula ly in unplanned inne a eas (§34
BauGB) (Bo he 2022: 200). Wi h such a land-use plan,
he use o land can be es ic ed o esiden ial buildings
ha mee he s anda ds o social housing p omo ion o o
which he de elope has en e ed in o an u ban de elopmen
con ac o comply wi h he p omo ion condi ions o social
housing (Deu sche Bundes ag 2020: 19). This egula ion
p ima ily se es o speed up he p epa a ion o specific a -
eas unde planning law, as ce ain pa icipa ion s eps can
be omi ed in he plan p epa a ion p ocedu e. This sub-
planning is also possible e en i o e all planning has no
ye been comple ed. The possibili y o d awing up a sec o al
land-use plan is limi ed un il 31 Decembe 2024.
4.2.4 Re ision o §17 BauNVO: The p e ious uppe
limi s o he ex en o building use become
o ien a ion alues
The alues o he ex en o building use, p e iously de-
fined as uppe limi s in §17 BauNVO, a e con e ed in o
o ien a ion alues by he new e sion o he egula ion. The
p e ious egula o y sys em s ipula ed compliance wi h he
uppe limi s in u ban land-use planning so ha exceeding
hese limi s was only possible as an excep ion equi ing jus-
ifica ion. This app oach has been abandoned. The e is no
longe an obliga ion o compensa e, as p e iously egula ed
Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604 595

A. Hengs e mann,N. Skala
in §17 pa a. 2 BauNVO as a p e equisi e o exceeding
he uppe limi s acco ding o §17 pa a. 1 BauNVO. This
conside ably expands he municipali ies’ scope o decision-
making abou he s ipula ions in he land-use plan on he
ex en o building use, so ha in he exis ing building a eas
i is possible o build mo e densely han be o e (Deu sche
Bundes ag 2020: 34).
4.2.5 In oduc ion o a new building a ea ca ego y (§5a
BauNVO)
On he commission’s ecommenda ion, “ u al esiden ial
a ea” is included in he Baunu zungs e o dnung as a new
esiden ial a ea ca ego y (Fimpel/Mülle 2022: 19). Such a -
eas se e esiden ial pu poses as well as he accommoda ion
o pa - ime ag icul u al and o es y businesses and com-
me cial en e p ises ha do no cause a significan dis u b-
ance (§5a BauNVO). Unlike illage a eas (§5 BauNVO),
such a eas a e no cha ac e ised by ull- ime ag icul u al
businesses bu by he coexis ence o housing, pa - ime busi-
nesses and non-dis u bing comme cial uses. This means ha
a land-use plan can now be d awn up o addi ional a eas
p e iously assigned o he unplanned ex e nal a ea acco d-
ing o §35 BauGB.
4.2.6 Ex ension o §13b BauGB
The egula ion §13b BauGB includes he possibili y o in-
cluding ou e a eas in an accele a ed p ocedu e, hus acili-
a ing building in unplanned ou e a eas. The p o ision was
in oduced in 2017 o be able o c ea e housing o e ugees
as quickly as possible and was ini ially limi ed un il 31
Decembe 2019. Now, in he cou se o he Baulandmobili-
sie ungsgese z, i has been ex ended un il he end o 2022
on he g ounds o he exis ing housing sho age. Howe e ,
he no m con adic s he p o ec ion o he ou e a ea and he
p io i y o inne -u ban densifica ion (Kmen 2020: 180).
4.3 Componen s a ec ing he disposal igh s
le el
The ollowing inno a ions a e in ended o s eng hen he
ac ual land mobilisa ion by he municipali ies.
4.3.1 S eng hening he municipal igh o p e-emp ion
(§§24, 25 BauGB)
Ge man building law p o ides o a municipal igh o fi s
e usal. In planning p ac ice, howe e , his has so a only
played a subo dina e ole. The Baulandmobilisie ungsge-
se z is in ended o inc ease he applicabili y o p e-emp ion
igh s unde §§24, 25 BauGB. Pu ely specula i e p ope ies
a e o be wi hd awn om he ma ke by making hem a ail-
able o de elopmen a e a building o de (§176 BauGB),
ei he on he pa o he owne o on he pa o he munic-
ipali y h ough a esale in connec ion wi h building o de s
(Fimpel/Mülle 2022: 20).
In pa icula , i is cla ified ha mee ing a housing need
in he municipali y and p omo ing inne de elopmen based
on an u ban de elopmen concep a e public wel a e con-
ce ns ha can jus i y he exe cise o he igh o fi s e usal
(§24 pa a. 3 p. 2 BauGB). In addi ion o unde eloped a eas,
p ope ies which a e al eady sligh ly de eloped a e now also
eligible o he exe cise o p e-emp i e igh s (§24 pa a. 1
p. 1 no. 6 BauGB). In addi ion, new municipal p e-emp i e
igh s a e in oduced o p ope ies in a deplo able (u ban
de elopmen ) s a e (§24 pa a. 1 p. 1 no. 8 BauGB) and o
unde eloped o ma ginally de eloped and de elic p ope -
ies in municipali ies wi h igh housing ma ke s as defined
in §201a BauGB (§25 pa a. 1 p. 1 no. 3 BauGB).
4.3.2 Ex ension o he building o de o a eas wi h
a igh housing ma ke (§176 pa a. 1 no. 3 (new)
BauGB)
In p inciple, building planning law only defines he ame-
wo k o pe missible de elopmen , bu i does no c ea e any
obliga ion o physically cons uc he pe missible de elop-
men . In ce ain cases, howe e , he municipali y can issue
a building o de agains he owne s o o ce he implemen-
a ion o a building measu e. Howe e , high legal equi e-
men s a e a ached o his, which is why he ins umen has
ecei ed mo e academic han p ac ical a en ion.
The exis en building o de was ex ended by he Bauland-
mobilisie ungsgese z in ha i is now possible o munici-
pali ies o o de owne s in a eas wi h igh housing ma ke s
o build on hei land wi h esiden ial uni s, p o ided ha
esiden ial use is pe mi ed in he land-use plan (§176 pa a.
1 no. 3 BauGB). The limi o his is he economic eason-
ableness o he owne . Wha is new he e is ha e en si es
wi h mino de elopmen a e now conside ed unde eloped,
which ex ends he applicabili y o he building o de . I he
owne is unable o comply wi h he building o de , hey can
demand ha he municipali y ake possession o he land in
ques ion o he benefi o hi d pa ies, whe eby he land
may only be ans e ed o municipal housing associa ions,
non-p ofi housing cons uc ion companies, coope a i es o
ounda ions. In his case, i is con ac ually s ipula ed as
a condi ion and equi emen ha he specific p ojec be e-
alised wi hin a pe iod o be de e mined.
4.4 E ec o Baulandmobilisie ungsgese z on
mobilising building land
The Baulandmobilisie ungsgese z aims o s eng hen he
municipali ies’ abili ies o ac i a e building land mo e
quickly and secu e affo dable housing, hus coun e ac ing
596 Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604
Making land a ailable. Cul u al legal compa ison o he Ge man Building Land Mobilisa ion Ac and he pa ial ...
he igh housing ma ke in Ge man ci ies. I is ques ionable
whe he his has been achie ed wi h hese amendmen s.
The new egula ions ocus on measu es ha pu ely im-
pac usage igh s and ha e li le o no influence on he phys-
ical de elopmen o he land. In addi ion, he amendmen s
o en only affec indi idual cases, such as he amended ex-
emp ion op ions unde §31 pa a. 2 and 3 BauGB. The new
egula ions wi h an effec on disposal igh s, on he o he
hand, a e only selec i ely ela ed o indi idual de ailed as-
pec s. The amendmen s o he p e-emp ion igh s in §§24,
25 BauGB expand he exis ing legal op ions o he munici-
pali ies. S ill, i is ques ionable whe he hey can help ease
he si ua ion in he housing ma ke since hey a e pu ely
eac i e ins umen s and he municipali ies canno ac on
hei own ini ia i e (Kmen 2020: 181).
The amendmen s o he building o de (§176 BauGB)
expand he egula ion’s field o applica ion, bu he ex en
o which hey can make a eal con ibu ion o he mobilisa-
ion o building land emains o be seen. E en in p e ious
planning p ac ice, he building o de did no play a signifi-
can ole, as i was conside ed oo “complica ed and cou -
hea y” (Pa ze all 2020: 27), a “blun swo d” (K au zbe ge /
S üe 2021: 37) wi h oo many obs acles o en o ceabili y.
In summa y, i can be said ha apa om new possibili-
ies o imp o e buildabili y, he e a e s ill ha dly any ins u-
men s a ailable o en o ce physical de elopmen . I emains
o be seen whe he he legisla i e changes lis ed he e can
ulfil he legisla o s’ in en ions. The Building Land Mobili-
sa ion Ac cu en ly seems o be only one s ep on he long
way o effec i e building land mobilisa ion.
5 Fi s pa ial e ision o he Swiss
Spa ial Planning Ac (2012)
In 2012, he Fede al Assembly passed a pa ial e ision o
he Spa ial Planning Ac (RPG).7The change ep esen s he
mos significan amendmen o Swiss planning law since
he o iginal codifica ion in 1979 (Knoep el/Csikos/Ge be
e al. 2012: 417–418). On he mobilisa ion o building land,
he e a e wo majo changes. Fi s ly, A icle 15 RPG speci-
fies he p o isions ha a e binding unde ede al law when
expanding he building zone, implici ly enla ging he c i-
e ia ca alogue o land-use designa ion. Secondly, explici
p o isions o p omo e he a ailabili y o building land we e
added and inco po a ed in o he law in a new A icle 15a
RPG. In addi ion, he p esc ip ions o compensa ing added
alue (A . 5, A . 38a RPG) and o s uc u e planning
7Bundesgese z übe die Raumplanung (Raumplanungsgese z)
(RPG) om 22. Juni 1979, S and am 1. No embe 2012.
(esp. A . 8a RPG) we e e o med as well, al hough hese
mechanisms o ac ion do no di ec ly affec he mobilisa ion
o building land.
5.1 Re o m’s con ex
Since 1969, spa ial planning has been explici ly lis ed in he
ca alogue o s a e esponsibili ies in he Swiss Cons i u ion
(BV).8Since hen, public ins i u ions ha e been empow-
e ed and obliged “ o ensu e he app op ia e and econom-
ical use o he land and i s p ope ly o de ed se lemen ”
(A . 75 pa a. 1 BV). Achie ing his cons i u ional objec-
i e is he esponsibili y o he can ons (A . 3, 42, 43 and
75 BV). Howe e , wi hin he amewo k o limi ed egu-
la o y powe , he Con ede a ion can also define p inciples
and e en conclusi ely egula e indi idual sub-a eas (G i -
el 2017a). In Swiss spa ial planning, a legal sys em has
de eloped in which he ede al go e nmen egula es he
o e a ching objec i es and p inciples and conclusi ely eg-
ula es hei applica ion in selec ed a eas (especially con-
s uc ion ou side he building zone). In essen ial a eas (es-
pecially cons uc ion wi hin he building zone), he can-
ons a e gi en amewo k condi ions, he implemen a ion
o which emains wi hin hei decision-making and legisla-
i e so e eign y.
The main body o ede al law is he 1979 Spa ial Plan-
ning Ac (RPG) and he p inciple o sepa a ion con ained
he ein, i.e. he di ision o land in o he building zone and
he non-building zone. The o me can be u he diffe -
en ia ed by can onal law, while he la e is conclusi ely
egula ed by ede al law (Hänni 2016: 255; G iffel 2017b:
58, 137). In he building zone, he e is eedom o build,
al hough a building pe mi is equi ed up on o ensu e con-
o mi y wi h planning and building law (Aemisegge /Moo /
Ruch e al. 2016a: 289). In he non-building zone, he e is
no eedom o build as long as he e is no explici excep-
ion unde ede al law (e.g. o ag icul u al buildings, in a-
s uc u e, o o he place- ela ed issues) (G iffel 2017b: 22).
In addi ion, he main p ocedu al ins umen s o planning
wi hin he building zone a e p edefined in he Spa ial Plan-
ning Ac , such as he s uc u e plan (usually a he can onal
le el) and he zoning plans (usually a he communal le el).
While he s uc u e plan is only binding o he au ho i ies,
he zoning plans a e di ec ly binding o he owne s: hus,
hey o m he legal basis o building pe mi s (Aemiseg-
ge /Moo /Ruch e al. 2016b: 65). The ede al go e nmen
me ely lays down abs ac condi ions abou which aspec s
8Bundes e assung de Schweize ischen Eidgenossenscha (BV)
om 18. Ap il 1999, S and am 13. Feb ua 2022.
Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604 597
A. Hengs e mann,N. Skala
mus be conside ed in zoning planning. The conc e e deci-
sion is he esponsibili y o he municipali ies.
The sys em aims o legally define he limi s and es ic-
ions on he owne s’ land use (Be isha/Co ella/Ri olin e al.
2021: 195). The ac ual implemen a ion o cons uc ion wo k
is a decision made by he owne s. In his espec , he sys-
em is passi e (Hengs e mann 2019). Building use o he
land is made possible and he co esponding incen i es a e
c ea ed. Howe e , he planning au ho i ies canno gua an ee
he physical implemen a ion o building wo k, so he p op-
e y owne s ha e a e o. Despi e he economic incen i es,
conside able a eas emain unused o unde used, e en in
high-p iced loca ions. P ecise quan ifica ion is difficul , bu
es ima es sugges ha Swi ze land’s building land ese es
could p o ide addi ional housing o 0.7 o 1.94 million in-
habi an s (Nebel 2014: 146). Howe e , i he de elopmen
p essu e is ins ead me by expanding he building zone, hen
his will esul in p ecisely hose sp awling spa ial s uc-
u es ha con adic he cons i u ional goals and he en i e
poli ical legi imacy o spa ial planning. P omo ing he mo-
bilisa ion o building land hus se es he achie emen o
objec i es and is no only sensible in planning e ms bu
legally equi ed.
Howe e , he ac ha he sys em does no wo k so e -
ec i ely in e e yday poli ical li e became clea o poli i-
cians and he elec o a e h ough he so-called Galmiz case
(Hengs e mann/Ge be 2015). Al hough he planning and
na u e conse a ion egula ions s ipula ed o he wise, a 55-
ha a ea in he municipali y o Galmiz in he can on o F i-
bou g was zoned o enable an indus ial de elopmen o
sa is y economic policy. The p ocedu e is ques ionable o
legal easons. Poli ically, howe e , i shows he weakness
o spa ial planning: he planning sys em canno p e en u -
ban sp awl i i p ima ily ies o p e en ex e nal de elop-
men (nega i e planning) (Koll-Sch e zenmay 2021). Wha
is needed is effec i e inne de elopmen (posi i e planning),
which equi es asse i e spa ial planning and ins umen s
o mobilising building land. This ealisa ion is he main
mo i e behind he pa ial e ision o he planning law (so-
called RPG1- e o m), which he Fede al Assembly enac ed
in 2012, which was app o ed by he elec o a e in 2013 wi h
62.9% in a ou , and which en e ed in o o ce on 1 May
2014.
5.2 Componen s a ec ing he usage igh s
le el
The RPG-1 e o m aims o inc ease he effec i eness o spa-
ial planning. In addi ion o A icle 8a RPG (can onal plan-
ning) and A icle 5 RPG (compensa ion o added alue)
(Hengs e mann/Scheiwille 2021), A icle 15 RPG (build-
ing zones) was e o med as well. This con ains he ede al
equi emen s o he local planning au ho i ies (usually he
municipali ies). Howe e , i is also indi ec ly essen ial o
p ope y owne s, as i de e mines which building zone hei
p ope y belongs o and hus whe he i can be buil on.
In he old e sion, A icle 15 RPG included h ee c i e ia
ha mus be ulfilled o land o be eligible o be assigned o
he building zone by municipal planning (so-called zoning).
The land mus be sui able, be se iced by he municipali ies
wi hin he nex 15 yea s and be expec ed o be needed
wi hin he same pe iod (A . 15 pa a. 2 RPG old e sion). In
compa ison, he new wo ding o he same a icle includes
u he quan i a i e and quali a i e gene al p inciples o he
building zone (A . 15 pa a. 1, 2, 3 and 5), as well as fi e
cumula i e c i e ia unde which condi ional land can be
newly assigned o he building zone (see Table 1).
The quan i a i e dimensions o he building zone mus
(as in he old e sion) be based on he an icipa ed demand
o he subsequen 15 yea s (A . 15 pa a. 1 RPG). I he
exis ing building zone al eady exceeds his an icipa ed de-
mand, he e is now an obliga ion o educe i (A . 15 pa a.
2RPG)(Huse 2019: 107). In addi ion, he calcula ion o
his equi emen is egula ed in de ail and made binding in
he o m o a echnical guideline (A . 15 pa a. 5 RPG).
The municipali ies a e also explici ly bound by planning
law equi emen s ega ding he quali y o he building zone
(A . 15 pa a. 3 RPG). Explici e e ence is made o he
binding con o mi y wi h he objec i es and p inciples o
planning (A . 1 and 3 RPG). In addi ion, he p inciple o
unc ional, i.e. c oss-bo de planning, applies (A . 15 pa a.
3 RPG) (Aemisegge /Moo /Ruch e al. 2016a). Taken as
a whole, hese new egula ions esul in he gene al p inci-
ples o building zones being defined much mo e p ecisely
(G iffel 2017b). They also esul in legally binding ame-
wo k condi ions wi hin which municipal zoning mus ake
place.
Since he e o m, fi e cumula i e c i e ia mus be ul-
filled when assigning land o he building zone (A . 15
pa a. 4 RPG): (i) sui abili y, which e e s o bo h echni-
cal and legal aspec s; (ii) need, se icing and de elopmen
wi hin he nex 15 yea s; (iii) he ese a ion ha cul i a ed
land is no agmen ed; (i ) he legal gua an ee o ac ual
a ailabili y; and ( ) compliance wi h he equi emen s o
he s uc u e plan. Wi h his ca alogue o c i e ia, he ede al
legisla u e has now gi en he municipali ies mo e p ecise
guidelines o hei spa ial de elopmen , which hey mus
ansla e in o binding specifica ions o he ype and ex en
o pe missible building use o land.
O e all, he densi y o land-use egula ions has inc eased
significan ly. While A icle 15 RPG in he 1980 e sion
se ed o p o ide an ini ial, na ionwide, uni o m defini ion
o building zones, he can ons now ha e significan ly mo e
p ecise equi emen s unde ede al law ega ding he quan-
598 Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604
Making land a ailable. Cul u al legal compa ison o he Ge man Building Land Mobilisa ion Ac and he pa ial ...
Table 1 Compa ison o A icle 15 RPG old and new e sions o Swiss Spa ial Planning Ac (RPG)
A . 15 RPG
Ve sion in o ce 1980-
2014
A . 15 RPG
Ve sion in o ce since 2014
Building zones shall
include land ha is
sui able o de elop-
men and
a) is al eady la gely
de eloped, o
b) will p obably be
needed and de eloped
wi hin 15 yea s.
1Building zones mus be de ined in such a manne ha hey mee he an icipa ed needs o he ollowing 15
yea s.
2Excessi ely la ge building zones mus be educed in size.
3The loca ion and sizeo he building zones mus be de ined in a manne no es ic ed by communalbound-
a ies, espec ing he aims and p inciples o spa ial planning. In pa icula , c op o a ion a eas mus be main-
ained and na u e and landscape p ese ed.
4Land may be assigned o a buildingzone o he i s ime i :
a. i is sui able o de elopmen ;
b. i will p obably also be needed, made eady o de elopmen and de eloped wi hin he nex 15 yea s e en
hough in e nal use ese es in exis ing building a eas ha e been exploi ed o hei ull po en ial;
c. a able land is no agmen ed as a esul ;
d. i s a ailabili y is gua an eed by law; and
e. he equi emen s o he s uc u e plans a e me he eby.
5The Con ede a ion and can ons shall oge he d aw up echnical guidelines o assigning land o building
zones, and in pa icula o calcula ing he a ea equi ed.
O icial ansla ion in Fedlex, p o ided by he Fede al Chancelle y
i y, quali y and condi ions o expanding he building zone.
The can ons’ scope o in e p e a ion (e.g. he in e p e a ion
o he an icipa ed demand) and legal loopholes (e.g. he
compensa ion o planning- ela ed added alue) ha e been
educed as a esul , e en hough his can lead o an inc ease
in equi emen s and conside able addi ional expendi u e in
local planning p ac ice.
5.3 Componen s a ec ing he disposal igh s
le el
The RPG-1 e o m also includes new p o isions ha affec
he le el o disposi ion law. Fo example, ac ual a ailabili y
is explici ly men ioned in A icle 15 RPG o new building
zones and is e en ex ended o old building zones wi h he
con empo a y A icle 15a RPG.
The a o emen ioned legally binding cumula i e c i e ia
o expanding he building zone also include ac ual a ail-
abili y (A . 15 pa a. 4 li . a and d RPG new e sion). Fi s ,
he echnical and legal sui abili y o he land o building
on (A . 15 li . b RPG old e sion) is adop ed om he old
egula ion as a manda o y c i e ion. In addi ion, i is now
compulso y ha he land is needed, se iced and buil on
wi hin he nex 15 yea s (A . 15 pa a. 4 li . b RPG new
e sion). In his lis , he legisla o hus adds a “de ac o
building obliga ion” (Hengs e mann/Ge be 2017) o heex-
is ing in as uc u e se ice obliga ion and he an icipa ed
need. Acco dingly, municipali ies mus legally ensu e ha
he land hey wan o assign o he building zone is ac ually
buil on. They mus also legally ensu e his ou come (A .
15 pa a. 4 li . d RPG new e sion), which can be achie ed
h ough gene al building code egula ions o indi idual con-
ac s wi h he landowne s. The la e means linking zoning
decisions o he consen and con ac ual ag eemen o he
landowne s. The conc e e building in en ion, schedule and
consequences in he e en o non-occu ence a e hen laid
down in he con ac . I applied, he legal consequence is
mos o en he akeo e o he land by he municipali y so
ha he implemen a ion o he zoning plans is also ensu ed,
unde he law o disposal i necessa y.
All in all, hese wo egula ions (A . 15 pa a. 4 li . a and
d RPG new e sion) mean ha in addi ion o he igh s o
use, he zoning p ocess now also includes deadlines wi h an
obliga ion o use he land, hus p e en ing u u e building
land om being hoa ded. I physical de elopmen does no
occu wi hin he ime limi , he o iginal zoning becomes
null and oid. I is hus wi hd awn wi hou compensa ion
(non-zoning) o he land is aken o e by he municipali y
a he gene al ma ke alue (exp op ia ion) and used o
de elopmen .
No included in he p o isions o A icle 15 RPG is build-
ing land unde he old law, i.e. land ha had al eady been
assigned o he building zone when he pa ial e ision came
in o o ce in 1980. To p omo e he a ailabili y o his land,
he legisla o has added he new A icle 15a RPG and es ab-
lished wo essen ial mechanisms in he p ocess. The a icle
s a es: “The can ons shall wo k wi h he communes o ake
he measu es ha a e equi ed so ha building zones a e
used o hei assigned pu pose” (A . 15a pa a. 1 RPG new
e sion). Apa om a e e ence o building land eadjus -
men (acco ding o A . 20 RPG), he conc e e measu es
a e no defined. Mo eo e , he idea o a building obliga-
ion is also aken up. Acco dingly, he can ons mus enac
conc e e, applicable egula ions wi h which building obli-
ga ions can be imposed (A . 15a pa a. 2 RPG new e sion)
(Hengs e mann/Ge be 2017: 16–17). Compa ed o A icle
Raum o schung und Raumo dnung | Spa ial Resea ch and Planning (2023) 81/6: 591–604 599