Article
Urban Studies
2021, Vol. 58(5) 959–976
Ó Urban Studies Journal Limited 2020
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sagepub.com/journals-permissions
DOI: 10.1177/0042098020940602
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The effect of upzoning on house
prices and redevelopment premiums
in Auckland, New Zealand
Ryan Greenaway-McGrevy
University of Auckland
Gail Pacheco
Auckland University of Technology
Kade Sorensen
University of Auckland
Abstract
We study the short-run effects of a large-scale upzoning on house prices and redevelopment pre-
miums in Auckland, New Zealand. Upzoning significantly increases the redevelopment premium
but the overall effect on house prices depends on the economic potential for site redevelopment,
with underdeveloped properties appreciating relative to intensively developed properties.
Notably, intensively developed properties decrease in value relative to similar dwellings that were
not upzoned, showing that the large-scale upzoning had an immediate depreciative effect on pre-
existing intensive housing. Our results show that the economic potential for site redevelopment
is fundamental to understanding the impact of changes in land use regulations on property values.
Keywords
house prices, land use regulations, redevelopment option, redevelopment premium, upzoning
Received April 2019; accepted June 2020
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Introduction
Upzoning is increasingly being advocated as a
solution to unaffordable housing (Freeman
and Schuetz, 2017; Glaeser and Gyourko,
2003). It refers to changes in regulatory land
use regulations (LURs) that enable more-
intensive site development (Gabbe, 2018).
Because LURs increase house prices by
restricting supply (Gyourko and Molloy,
2015), it is thought that a relaxation of these
regulations through upzoning can reduce
dwelling prices by enabling construction of
intensive housing (Freeman and Schuetz,
2017; Glaeser and Gyourko, 2003). Several
major cities in the USA have recently upzoned
large areas in response to rising housing costs,
including Minneapolis, Portland and Seattle
(National Public Radio, 2019).
However, our understanding of the
impact of upzoning on house prices is limited
by a lack of empirical research on the topic
(Freemark, 2019a; Schill, 2005).
1
Real option
theory suggests that upzoning might instead
increase house prices by enhancing the rede-
velopment premium embedded in property
values. The option to augment or tear down
and replace a residential structure can carry
a significant premium (Clapp and Salavei,
2010; Clapp et al., 2012a, 2012b) and upzon-
ing may increase the value of this redevelop-
ment premium by enhancing the extent of
permissible development on a parcel of land.
Understanding how these opposing apprecia-
tory and depreciatory effects of upzoning are
mediated by various factors, such as the
redevelopment potential of affected parcels,
the scale of the policy and the passage of
time, is critical to evaluating the efficacy of
upzoning to enhance housing affordability.
In this paper we examine the short-run
impact of upzoning on house prices using an
empirical method that distinguishes increases
in redevelopment premiums from other mar-
ket equilibrium effects of the policy, such as
increases in housing supply. Our study is
based on a policy intervention that upzoned
large areas within the metropolitan region of
Auckland, New Zealand (NZ). To analyse
the effects of this policy change, we embed a
difference-in-differences structure in a hedo-
nic pricing function, wherein an upzoning
quasi-treatment is interacted with a conven-
tional measure of site development: intensity.
Intensity is the ratio of the value of improve-
ments to the total property value and is often
used in empirical hedonic regressions to
measure redevelopment premiums because it
reflects the economic potential for site rede-
velopment (Clapp and Salavei, 2010; Clapp
et al., 2012a). Intuitively, the opportunity
cost in terms of foregone rent from tearing
down an apartment block (with a corre-
spondingly high intensity ratio) is much
greater than the opportunity cost of tearing
down a small house on a large land parcel
(with a low intensity ratio). The former
therefore has less economic potential for
redevelopment than the latter and corre-
spondingly carries a smaller redevelopment
premium. By conditioning on intensity, we
can isolate enhancements in redevelopment
premiums from other policy effects on
prices, such as decreases in prices due to
actual or anticipated construction. These
ideas are theoretically formalised in the third
section of this paper using the Clapp and
Salavei (2010) real option model.
We find that upzoning significantly
increases the hedonic estimate of the redeve-
lopment premium. However, the net effect
on house prices is decreasing in intensity,
meaning that underdeveloped properties
appreciate relative to intensively developed
properties. Further, upzoned properties that
Corresponding author:
Ryan Greenaway-McGrevy, University of Auckland, Economics, 12 Grafton Road, Auckland 1024, New Zealand.
Email: r.mcgrevy@auckland.ac.nz
960 Urban Studies 58(5)
exceeded a sufficiently high level of intensity
decreased in price relative to non-upzoned
properties, illustrating that the large-scale
upzoning had an immediate depreciative
effect on pre-existing forms of intensive
housing. The existing extent of site develop-
ment is therefore identified as a key attribute
mediating the appreciatory and depreciatory
impacts of upzoning. These results hold
under several robustness checks and placebo
tests.
This paper makes several contributions to
the literature. First, while a tremendous
amount of research has focused on the
static effect of cross-sectional variation in
LURs (see Gyourko and Molloy, 2015;
Pogodzinski and Sass, 1991; Quigley and
Raphael, 2005, for reviews), there has been
much less research on the effects of dynamic
changes in zoning restrictions, in part
because large-scale changes in regulations
are rare (Freeman and Schuetz, 2017).
2
We
break new ground on this understudied topic
by examining a policy intervention in which
most of the residential land in the metropoli-
tan urban area was upzoned. Second, by
identifying intensity as a key attribute med-
iating price effects, we reconcile the fact that
upzoning can decrease average dwelling
prices by enabling supply of more intensive
forms of housing, while increasing the value
of properties that are more-endowed with
land relative to those that are less-endowed,
as predicted by real option theory. In eco-
nomic terms, upzoning reduces the minimum
amount of land required to produce a dwell-
ing, and this increase in land productivity is
captured both by consumers, through lower
dwelling prices, and by landowners, through
larger factor payments to land. Because a
property is a bundle of land and dwelling,
the net price effect of upzoning depends on
the relative value of its land endowment.
Finally, our approach helps assess the cred-
ibility of market-led policies to improve
housing affordability. Housing construction
can be impeded by land assembly problems
(O’Flaherty, 1994) and other regulatory bar-
riers (Schill, 2005). Our hedonic model per-
mits us to price intensively developed (i.e.
high intensity) dwellings to uncover whether
prices on such properties decrease after the
policy is announced.
Our data set offers some unique advan-
tages that assist in identifying the effects of
upzoning. First, non-upzoned houses pro-
vide a quasi-control, thereby permitting a
difference-in-differences approach that miti-
gates some of the concerns related to the
endogeneity of regulations in the cross-
sectional setting (Gyourko and Molloy,
2015). Second, there is a unique identifier
for each property, which enables use of
repeat sales to control for time-invariant fac-
tors affecting house prices over the sample
period. Third, the dataset is sufficiently
detailed so that we can control for numerous
other potential confounding factors, such as
proximity to the central business district
(CBD). Finally, we can match the transacted
property to its residential planning zone, so
that we can pinpoint upzoning in space and
time, rather than estimating where and when
rezoning occurred.
The remainder of the paper is organised
as follows. The following section reviews the
extant literature on zoning, house prices,
and affordability. The third section contains
a detailed description of the institutional
background underlying our study. The next
section presents the theoretical foundation
for our empirical regressions. Empirics are
contained in the penultimate section and the
final section concludes.
Literature review
Numerous studies have analysed the rela-
tionship between zoning regulations and a
variety of outcomes, including house prices
and affordability, construction and rents
(surveys include Gyourko and Molloy, 2015;
Greenaway-McGrevy et al. 961
Pogodzinski and Sass, 1991; Quigley and
Raphael, 2005). The majority of studies find
that locations with more regulation have
higher house prices and less construction,
although planning endogeneity limits our
ability to infer causality from these correla-
tions (Gyourko and Molloy, 2015).
Nonetheless, empirical studies that account
for endogeneity frequently find that tighter
LURs cause increases in house prices
(Dalton and Zabel, 2011; Hilber and
Vermeulen, 2016; Ihlanfeldt, 2007; Jackson,
2016) and decreases in construction
(Chakraborty et al., 2010; Glaeser and
Ward, 2009; Jackson, 2016).
On the basis of this and other work,
many researchers argue that a relaxation of
LURs will improve affordability and acces-
sibility by enabling more housing construc-
tion (Freeman and Schuetz, 2017; Glaeser
and Gyourko, 2003; Manville et al., 2020).
Yet, many others remain sceptical of the
capacity for upzoning to deliver affordable
housing, arguing that benefits to lower-
income households are limited (Favilukis
et al., 2019; Rodriguez-Pose and Storper,
2020). Part of the problem is that our under-
standing of the manifold impact of upzoning
on prices is limited by an acute lack of
empirical research on the topic (Freeman
and Schuetz, 2017; Schill, 2005). Research
adopting a quasi-experimental approach to
examine price effects of zoning changes is
limited to Atkinson-Palombo (2010) and
Freemark (2019a). Notably, Freemark
(2019a) finds that multifamily buildings
appreciated relative to controls in Chicago
after transit-oriented upzoning.
In addition to upzoning, other policies
intended to reduce impediments to market-
led supply include relaxing urban growth
boundaries (Anacker, 2019); reducing unne-
cessary regulations and making the develop-
ment process more certain and transparent
(Freeman and Schuetz, 2017); and accelerat-
ing land-use and construction approvals
(Anacker, 2019). Other researchers instead
advocate for direct state intervention.
Wetzstein (2019) argues that non-market-
based housing supply, demand-side interven-
tions and urban land market interventions
are required to ensure housing affordability,
while Favilukis et al. (2019) show that direct
state-led interventions, such as vouchers and
accurately targeted inclusionary zoning,
more effectively enhance affordability in a
calibrated spatial equilibrium model.
Meanwhile Been et al. (2019) argue for a
broad policy package that includes both
state intervention and the removal of impedi-
ments to market-led construction. Freemark
(2019b) also advocates for a combination of
large-scale state-led intervention and regula-
tory reform, pointing out that housing unit
construction doubled in Paris after renewed
government support for affordable housing,
repurposing of public land, LUR reform and
the introduction of financial incentives for
private-sector construction.
Institutional background
Auckland is the largest city in NZ, with an
estimated population of approximately
1.7 million in 2017 (Auckland Council,
2017). The region covers 489,363 ha, of
which 50,550 ha constitute the core urban
area (Auckland Council, 2017). From
November 2010 the entire region fell under
the jurisdiction of the Auckland Council
(AC), formed after amalgamation of eight
different city and district councils. Auckland
has a population-weighted density of
approximately 4310 people per km
2
(source:
authors calculations based on 2013 census
data), and the population is evenly distribu-
ted outside the CBD (see Figure A1 in the
online Supplemental Material).
962 Urban Studies 58(5)
Auckland’s house prices roughly doubled
between 2009 and 2016 (see Supplemental
Figure A2), which resulted its housing being
ranked among the most unaffordable in the
world (Demographia, 2018). This increase
was predominantly unique to Auckland
within NZ. Prices have remained flat since
2016, coinciding with successive govern-
ments implementing policies to stem demand
and the central bank restricting credit
through tighter macroprudential policies.
Recent changes under the Auckland
Unitary Plan (AUP) make Auckland an
ideal case study to investigate the effects of
large-scale upzoning in a metropolitan area.
The AUP relaxed regulations to permit
increased density in large areas of the city
(Balderston and Fredrickson, 2014: 21). Key
milestones in development and implementa-
tion of the AUP are summarised below:
July 2010: The Local Government Act
2010 passed by the NZ government
requires AC to develop a consistent set
of urban planning rules.
15 March 2013: AC released the ‘draft’
AUP, followed by 11 weeks of public
consultation.
30 September 2013: AC released the
Proposed AUP (PAUP) and notified the
public that the PAUP was open for
submissions.
April 2014 to May 2016: An
Independent Hearings Panel (IHP) was
appointed by the NZ government and
subsequently held 249 days of hearings.
22 July 2016: the IHP set out recom-
mended changes to the PAUP. One of
the significant recommendations was
abolition of minimum lot sizes (except
for new subdivisions). AC considered
and voted on the IHP recommendations
over the next 20 working days.
19 August 2016: AC released the ‘deci-
sions’ version of the AUP. Several of the
IHP’s recommendations were voted
down but abolition of minimum lot sizes
was maintained.
8 November 2016: AC notified the pub-
lic through the media that the final AUP
version would become operational 15
November 2016.
3
All AUP versions (‘draft’, ‘proposed’, ‘deci-
sions’ and ‘final’) proposed new zoning regu-
lations that were easily viewed online. Any
interested member of the public could
observe the proposed regulations applying
to any given parcel in the city.
We focus on four residential zones intro-
duced under the AUP, listed in declining lev-
els of permissible site development: Terrace
Housing and Apartments; Mixed Housing
Urban; Mixed Housing Suburban; and Single
House. See Supplemental Table A1 for an
overview of the LURs by zone. These regula-
tions include site coverage ratios and height
restrictions, among others. For example,
between five and seven storeys and a maxi-
mum site coverage ratio of 50% is permitted
in Terrace Housing and Apartments, whereas
only two storeys and a coverage ratio of
35% is permitted in Single House. Together,
these four zones comprise over 90% of the
transactions in our sample.
AC estimated that the new zones
increased capacity for new dwellings by over
300%,
4
illustrating the large-scale nature of
the upzoning policy. Figure 1 depicts the
geographic distribution of the four zones
across the city. Mixed Housing Suburban is
the largest zone by area, covering 44.6% of
all residential land (source: authors’ calcula-
tions), while Mixed Housing Urban covers
22.5%. Single House is predominantly
located either very close to or at the CBD
outskirts, and covers 25.5% of residential
land. Terrace Housing and Apartments cov-
ers only 7.4% of residential land.
Our empirical design treats the AUP
announcement as a quasi-natural experiment
5
(where Single House acts as the control; see
Greenaway-McGrevy et al. 963
section ‘Econometric model’). We therefore
must select a time period ‘before’ and ‘after’
the treatment has occurred. Unfortunately, as
is clear from the timeline above, there is no
clean, singular announcement. We adopt a
conservative approach and take the years
between 2010 and 2012 (inclusive) as pre-
treatment (whic h pre-dates release of the
(first) draft AUP), and September 2016 to
December 2017 as post-treatment (immedi-
ately after the final ‘decisions’ AUP version is
released). We explore several other time peri-
ods in our robustness checks.
Theoretical framework
In this section we repurpose the Clapp and
Salavei (2010) real option model of housing
redevelopment to examine what happens to
property values when restrictions on devel-
opment are relaxed (as occurs under upzon-
ing). These theoretical predictions are
empirically tested in the following section.
Full details are provided in the Supplemental
Material.
The set-up is as follows. Each developed
property has a vector of characteristics q
0
that earn rents p and depreciate at rate d.
Future rents p (and characteristics q
0
) are
known with certainty. The property owner is
permitted to redevelop to the standard given
by q
n
. The cost of redevelopment is k qðÞ,
such that the construction costs are a func-
tion of q 2 R
.0
, and where we assume that
k qðÞ. 0, so costs are positive. Then the
value of the property is
Figure 1. Residential zones in Auckland.
Notes: The dot close to the centre of the maps is the location of the ‘Skytower’ within the CBD. Solid black lines
demarcate coastline.
964 Urban Studies 58(5)
V
0
=v
0
q
0
+ v
0
q
n
q
0
ðÞk(q
n
)ðÞ
v
0
q
n
k(q
n
)
v
0
q
0

r
d
r
r + d

r
d
ð1Þ
where v =
p
r + d
and r is the discount rate.
The redevelopment premium is the second
term. It disappears if q
n
= q
0
. We assume
v#(q
n
2q
0
)>k(q
n
).
We consider what happens to V
0
when
the policymaker increases an element of q
n
that represents an overall measure of devel-
opment intensity (call it q
iðÞ
n
). We can there-
fore think of upzoning as an exogenous
increase in q
iðÞ
n
. By taking the partial deriva-
tive of V
0
with respect to q
iðÞ
n
(refer to the
Supplemental Material for details), we obtain
two key results to be empirically tested:
(1) An increase in q
iðÞ
n
through upzoning
increases the property value, all else
equal.
(2) The increase in property value is
decreasing in q
iðÞ
0
, meaning that a prop-
erty with a lower initial level of site
development will experience a larger
increase in price from upzoning, all else
equal.
Although the model abstracts from mar-
ket equilibrium effects of upzoning, such as
the impact of increased housing supply on
house prices, it can straightforwardly accom-
modate common changes in house prices
brought about by shifts in supply and
demand. If housing in upzoned and non-
upzoned areas become imperfect substitutes
after upzoning, this reasoning yields a third
prediction:
(3) Anticipated dwelling construction in
upzoned areas decrease property prices
in upzoned areas relative to non-
upzoned areas.
Thus, the appreciatory effects of upzoning
via the redevelopment channel (1) are poten-
tially offset or altogether dominated by the
depreciatory effects of increased construc-
tion (3). The relative magnitude of these
opposing effects is mediated by the extent of
site development, q
iðÞ
0
, as stipulated under
(2). For example, properties that are already
developed to the extent permitted after
upzoning might depreciate relative to simi-
larly developed properties that were not
upzoned, since these properties have no
redevelopment potential.
Note that effects (1) and (3) become evi-
dent by comparing outcomes in upzoned
areas relative to non-upzoned areas. Our
conceptual framework does not, therefore,
identify average changes in redevelopment
premiums and house prices across the city. It
does, however, permit us to uncover evi-
dence of these city-wide effects because it
suggests that upzoning manifests as a dis-
tinct and identifiable pattern in house price
changes between upzoned and non-upzoned
areas provided we condition on site develop-
ment. Specifically, (3) should manifest as
upzoned, pre-existing high intensity dwell-
ings appreciating relative to non-upzoned,
pre-existing high intensity dwellings.
Meanwhile, (1) manifests as underdeveloped,
upzoned properties appreciating relative to
underdeveloped, non-upzoned properties.
Finally, note that (3) can be consistent
with no overall increase in the city’s dwelling
stock if upzoning only reallocates antici-
pated future construction from non-upzoned
to upzoned areas. It is therefore critical to
carefully check for evidence of this potential
demand shift on house prices and, if neces-
sary, control for it, before concluding that
the policy generated an overall increase in
Greenaway-McGrevy et al. 965
anticipated dwellings. We explore this possi-
bility in our spillover robustness checks (sec-
tion ‘Treatment spillovers’).
Empirics
Data
Our primary dataset consists of all residen-
tial property sales in Auckland between 2010
and 2017 (inclusive). The dataset contains
various information on the transacted prop-
erties, including: the sales price (excluding
chattels); date of sale; assessed value of land
and improvements; land area (in hectares),
where applicable; floor area and site foot-
print (in square metres); whether the land
title is freehold or leasehold; dwelling type
(house, unit or apartment); number of bed-
rooms and bathrooms; decade of construc-
tion; latitude and longitude of the property;
and Area Unit (AU) in which the property is
located.
6
Each house has a unique identifier,
so we can track sales of individual properties
over time. We clean the data to remove
transactions that appear to have had infor-
mation incorrectly coded or omitted, that
appear to be non-market transactions or
that are not relevant to our study (see the
Supplemental Material for details).
We also identify properties with joint
ownership of the land underlying the build-
ing, such as apartments and cross-leases.
7
In our preferred specification we limit the
sample to titles with exclusive land owner-
ship, since redevelopment of these sites is
not affected by title assembly problems
(O’Flaherty, 1994). However, a robustness
check reveals that this has no impact on our
results (see section ‘Including properties with
joint land ownership’).
The intensity ratio plays a significant role
in our empirics. It is constructed as:
intensity =
IV
AV
= 1
LV
AV
ð2Þ
where AV is total assessed value, LV is
assessed land value and IV is the improved
value (or capital value) of the property. IV
=AV2 LV holds as an identity. Assessed
values are based on local government valua-
tions for levying property taxes. The redeve-
lopment premium is decreasing in intensity,
meaning that negative coefficients on inten-
sity in hedonic regressions indicate a positive
premium. By construction the ratio lies
between zero and one, but the ratio does not
exceed 0.8 in our sample.
We use longitude and latitude to identify
the planning zone in which the property is
located, retaining transactions in the four
main residential zones introduced in the
third section: Terrace Housing and
Apartments (which we refer to as ‘Zone 4’);
Mixed Housing Urban (‘Zone 3’); Mixed
Housing Suburban (‘Zone 2’); and Single
House (‘Zone 1’).
8
Additional variables are generated and
employed as controls. We identify houses
with two or more storeys (by comparing
floor area to site footprint), we derive the
approximate building age (difference
between the date of sale and decade in which
the building was constructed),
9
and longi-
tude and latitude are used to calculate dis-
tance to the CBD.
10
To control for
neighbourhood income, we use the median
household income for the AU in which the
property is located.
11
Econometric model
Suppose that the policy is announced in time
period t
0
. Our regression is
1
T
i
p
i, t
1
p
i, t
1
ðÞ= b
1
+
X
m
s = 2
b
s
zone
s, i
+ d
1
intensity
i
+
X
m
s = 2
d
s
zone
s, i
intensity
i
+ g
0
X
i
+ e
i
ð3Þ
966 Urban Studies 58(5)
where:
i=1,.,n indexes the transactions
(houses) in the sample.
p
i, t
1
is log sales price (excluding chat-
tels) of house i in period t
1
\t
0
(i.e.
before the announcement); p
i, t
1
is log
sales price (excl. chattels) of house i in
period t
1
.t
0
.t
1
. A property is there-
fore included in our sample if it was sold
in period t
1
and in period t
1
. In our
baseline empirical specification, we use
the years 2010 through 2012 (inclusive)
for t
1
and September 2016 to December
2017 for t
1
, which leaves 2340 observa-
tions. If a house was sold more than
once within t
1
or t
1
, we use the first
transaction in the period.
T
i
denotes the years between the sale of
house i in period t
1
and period t
1
,so
that the dependent variable is an annual-
ised rate of inflation. The average num-
ber of years between transactions is 5.64.
fzone
s, i
g
m
s = 2
are upzoning dummies for
Zone 2, Zone 3 and Zone 4, respectively.
Thus m=4. The reference group is
Zone 1 (Single House).
intensity
i
is intensity (see eq. (2)) in
period t
1
.
X
i
is a vector of controls including prop-
erty attributes and neighbourhood infor-
mation: (log) land area; (log) floor area;
a dummy variable indicating two or
more storeys; number of bedrooms;
number of bathrooms; approximate
building age; (log) distance to CBD;
12
and (log) median household income for
the AU. We report regression results
with and without these controls.
Eq. (3) is the first difference of a conven-
tional difference-in-differences regression
where the treatment i s interacted with
intensity. In the Supplemental Material we
demonstrate this equivalence step-by-step.
Table 1 documents sample descriptive
statistics for the variables in the model.
Supplemental Table A2 contains these
descriptives stratified by residential zone,
showing that sales in zones that permit more
intensive development tend to be closer to
downtown and in suburbs with lower
incomes. Average intensity is similar across
all four zones.
Approximately one-quarter of the trans-
actions (25.5% = 597/2340) fall into the
Single House zone, which acts as our quasi-
control. 51.2% (= 1199/2340) are in Mixed
Table 1. Summary statistics.
Mean Median Std dev. Skew 1st perc 5th perc 95th perc 99th perc
Price appreciation 0.12 0.12 0.03 20.80 0.04 0.07 0.18 0.21
Intensity 0.43 0.44 0.13 20.25 0.10 0.21 0.63 0.70
Land area (ha) 0.07 0.07 0.03 4.85 0.02 0.03 0.11 0.18
Floor area (m
2
) 154.61 140.00 62.34 1.02 70.00 80.00 274.50 340.60
Bedrooms 3.48 3.00 0.74 0.40 2.00 3.00 5.00 5.00
Bathrooms 1.65 2.00 0.74 1.04 1.00 1.00 3.00 4.00
Building age (yr) 38.72 40.00 26.40 0.64 1.00 2.00 92.00 102.00
Dist. to CBD (km) 17.89 14.37 11.43 1.25 2.24 4.47 41.91 51.27
AU income
(NZ$ 000)
64.60 61.60 15.52 0.01 36.90 42.00 95.50 100.00
Notes: Price appreciation is the average annual change in log prices and is based on repeat sale residential transactions
between the pre-treatment sample (January 2010 to December 2012) and the post-treatment sample (September 2016
to December 2017). AU income is median household income (NZ$) in the Area Unit (suburb) of the transaction and is
obtained from the 2006 census. ‘Skew’ denotes skewness, while ‘perc’ denotes percentile.
Greenaway-McGrevy et al. 967
Housing Suburban and 18.3% (= 428/2340)
fall into Mixed Housing Urban. Only 5% (=
116/2340) of the transactions fall into the
Terrace Housing and Apartments zone, which
permits the most site development.
Several features of eq. (3) are worth
remarking on.
(1) The coefficients d
s
fg
m
s = 2
capture the
effect of upzoning on the redevelop-
ment premium. Recall that the coeffi-
cient on the intensity ratio from
hedonic regressions is used to estimate
the redevelopment premium. The coef-
ficient d
1
therefore captures the change
in the redevelopment premium for the
reference group (Zone 1), which was
not subject to upzoning. In turn, coeffi-
cient d
4
captures the change in the
redevelopment premium for houses
located in Zone 4 relative to the change
in the redevelopment premium for
houses in Zone 1. A priori we expect
this coefficient to be negative since the
redevelopment premium is decreasing
in intensity and upzoning should
increase the redevelopment premium.
Similar statements can be made about
d
2
and d
3
for Zones 2 and 3.
(2) Because the dependent variable is the
change in individual house prices, the
empirical model controls for time-
invariant confounding factors affecting
house prices over the sample period. In
this regard, our approach is like that
advocated by Dalton and Zabel (2011)
and Gyourko and Molloy (2015: 1303–
1304), who suggest panel data can be
used to address the endogeneity of reg-
ulations. Note that our difference-in-
differences model is not based on a
repeated cross section (c.f. Freemark,
2019a), but a panel.
(3) The vector X
i
includes property attri-
butes and geographic characteristics to
control for any remaining confounding
factors that vary over the sample
period. For example, an increase in
transport congestion may have inflated
the premium for houses closer to
downtown, hence we control for dis-
tance to the CBD. Because the empiri-
cal model is a time-differenced hedonic
regression, the parameters associated
with X
i
can be interpreted as changes
in the hedonic coefficients on the attri-
butes between t
1
and t
1
.
Regression results
Column (A) in Table 2 reports regression
results. It includes results for when all con-
trols are omitted and when controls related
to the geographic characteristics (household
income and distance to downtown) are
omitted. See columns (B) and (C).
The coefficients on the three upzoning
dummy variables interacted with intensity
are negative and statistically significant.
This is strong evidence of upzoning increas-
ing the redevelopment premium (see Remark
(1) in the preceding section). Furthermore,
note that the magnitudes of these coefficients
correspond to the ordinal ranking of permis-
sible site development under each zone.
The coefficients on the upzoning dummy
variables (not interacted) are positive and
statistically significant, indicating that an
upzoned property with intensity of zero (i.e.
equivalent to an empty lot) appreciated rela-
tive to non-upzoned properties. The magni-
tudes of the estimated coefficients again
correspond to the ordinal ranking of permis-
sible development under each zone.
Interestingly, the coefficient on intensity
(not interacted) is statistically indistinguish-
able from zero. This suggests that there was
no change in the redevelopment premium
for the quasi-control group after the
announcement.
Next, to illustrate how the effect of
upzoning on overall house prices depends
968 Urban Studies 58(5)
on existing site development, we use the
estimated regression model to construct pre-
dicted changes in house prices conditional
on both the residential zone and the inten-
sity ratio. For each of the four zones,
Figure 2 plots the expected annualised price
appreciation conditional on intensity. For
this exercise we set the control variables in
X
i
to their sample means to construct pre-
dicted values.
First, we consider Zone 4, which permits
the most site development. Holding all else
equal, the model implies that houses located
in this zone appreciated by between 14.7%
(intensity = 0) and 9.3% per year (intensity
= 1). This illustrates how intensity mediates
the impact of upzoning on house prices,
with properties that had relatively little site
development (i.e. low intensity) appreciating
relative to properties with more site develop-
ment (i.e. high intensity).
However, recall that intensity does not
exceed 0.8 in our sample. We therefore also
consider appreciation rates for houses with
Table 2. Regression results.
(A) (B) (C) (D) (E) (F)
Constant 0.324*** 0.214*** 0.129*** 0.360*** 0.189*** 0.126***
Zone 4 0.037*** 0.042*** 0.042*** 0.027*** 0.033*** 0.033***
Zone 3 0.032*** 0.034*** 0.034*** 0.026*** 0.029*** 0.028***
Zone 2 0.020*** 0.021*** 0.015*** 0.018*** 0.020*** 0.014***
Intensity 0.003 0.003 –0.044*** 20.003 0.005 –0.034***
Zone 4
3 Intensity
20.057*** 20.064*** 20.056** 20.050*** 20.059*** 20.056**
Zone 3
3 Intensity
20.048*** 20.050*** 20.044*** 20.039*** 20.041*** 20.036***
Zone 2
3 Intensity
2
0.027** 20.029*** 20.017 20.026*** 20.030*** 20.017*
ln(land) 0.001 20.002 20.002 20.001
ln(floor) 20.025*** 2 0.026*** 20.020*** 20.023***
Bedrooms 0.002 0.002 0.003*** 0.003***
Bathrooms 0.003** 0.003** 0.002** 0.002*
multiple storey
dummy
20.000 0.005 20.001 20.001
ln(age) 0.003*** 0.003*** 0.004*** 0.004***
Land dummy 0.002 0.003
Apartment
dummy
20.005 20.006
ln(distance) 20.004** 20.002**
ln(AU income) 20.009** 20.016***
R-squared 0.147 0.143 0.092 0.127 0.120 0.067
Adjusted
R-squared
0.141 0.138 0.089 0.123 0.116 0.065
Observations 2340 2340 2340 3695 3695 3695
Notes: OLS estimates of the regression equation (3). (A), (B) and (C) are based on the sample of properties with exclusive
land ownership. (D), (E) and (F) are based on the sample that includes properties with joint land ownership on the title (such
as apartments and houses on cross-leased parcels). We include dummy variables for properties with exclusive land titles and
apartments or units in models (E) and (F). The dependent variable is annualised percent change in repeat sale residential
transactions between the pre-tre atment sample (January 2010 to December 2012) and the post-treatment sample
(September 2016 to December 2017). ***, **, * denote significance at the 1%, 5%, and 10% levels, respectively , based on
Conley (1999) spatial dependence and heteroscedasticity robust standard errors with a 10 km bandwidth. Zone 4 is the most
intensive residential zone under the new LURs; Zone 1 is the least intensive. R-squareds are expressed as a proportion of 1.
Greenaway-McGrevy et al. 969
an intensity at either end of the empirical
distribution specifically at the 1st and 99th
percentiles. Across all zones, the 1st and
99th percentiles of the intensity ratio are
0.103 and 0.705 (see Table 1). The model
implies that Zone 4 properties at the 1st per-
centile appreciated by 14.1% on average,
whereas properties at the 99th percentile
appreciated by 10.9%.
Next, we consider Zone 1, which permits
the least site development and is the quasi-
control. The coefficient on intensity is close
to zero, which implies very little variation in
expected house price appreciation condi-
tional on intensity, varying between 11.0%
(intensity = 0) and 11.3% (intensity = 1).
The difference in appreciation rates at the
1st and 99th percentiles of intensity is smaller
(11.0% versus 11.2%).
The difference in appreciation rates
between Zone 4 (upzoned) and Zone 1 (non-
upzoned) reveals how the price impact of
upzoning depends on intensity. This differ-
ence is depicted in Supplemental Figure A4.
Notably, houses in Zone 4 with intensity
above 0.63 (the 95th percentile) depreciated
when compared with houses in Zone 1 with
intensity above 0.63. This implies that
upzoning decreased prices on pre-existing
high intensity housing. Conversely, houses
Terrace Housing and Apartments (Zone 4) Mixed Housing Urban (Zone 3)
Mixed Housing Suburban (Zone 2) Single House (Zone 1)
Figure 2. Expected price appreciation conditional on intensity ratio and residential zone.
Notes: Conditional expectations are based on OLS estimation of (3). See Table 2 for estimated coefficients. Dashed lines
represent 95% confidence intervals. Standard errors are robust to spatial dependence and heteroscedasticity.
970 Urban Studies 58(5)
in Zone 4 with intensity below 0.63 appre-
ciated relative to houses in Zone 1 with
intensity below 0.63, implying that upzoning
increased prices of moderate and low inten-
sity housing.
Predicted price changes in Zones 2 and 3
further corroborate the predictions of the
real option model. Houses located in Zone 3
(which permits more development than
Zones 1 and 2, but less than Zone 4) appre-
ciated by between 14.1% (intensity = 0) and
9.7% (intensity = 1). Corresponding figures
at the 1st and 99th percentiles are 13.7% and
11.1%. Houses located in Zone 2 (which per-
mits more development than Zone 1, but less
than Zones 3 and 4) appreciated by between
13.0% (intensity = 0) and 10.6% (intensity =
1) per year. Corresponding figures at the 1st
and 99th percentiles are 12.7% and 11.3%.
A consistent pattern emerges. The impact
of upzoning on prices diminishes as intensity
increases. Beyond a sufficiently high inten-
sity, the upzoned property depreciates rela-
tive to similar properties that were not
upzoned.
The statistically significant controls also
merit brief comment. House price apprecia-
tion is decreasing in distance to downtown
(perhaps reflecting increased congestion
costs), increasing in building age, and increas-
ing in number of bathrooms (consistent with
the well-documented increase in population
pressures in Auckland over the sample
period). Interestingly, however, after condi-
tioning other controls, including the number
of bedrooms and bathrooms, larger homes
appreciated by less over the sample period.
One potential drawback of our approach
is that we do not take into account the resi-
dential zone of the transacted house prior to
the AUP implementation.
13
For example,
houses rezoned to Terrace Housing and
Apartments may have already been in areas
that permitted intensive development.
However, there is no statistically significant
difference in either the average population
densities across the four zones in our sample
of transactions, suggesting that this is
unlikely.
14
Robustness checks
Including properties with joint land ownership. We
expand the sample to include properties that
have joint ownership of the underlying land
on the title, which includes apartments and
houses on cross-leased sites. We alter the
empirical specification slightly by including
dummy variables for properties with exclu-
sive land ownership
15
and for dwellings iden-
tified as apartments. Results are reported in
columns (D) through (F) of Table 2.
Our main findings are unaffected. First,
the coefficients on intensity interacted with
the upzoning treatments are negative and
statistically significant. Second, price appre-
ciation is decreasing in site intensity:
Supplemental Figure A3 shows that pre-
dicted price appreciations (by residential
zone and conditional on intensity) are very
similar to those exhibited in Figure 2.
However, the fitted model implies that a
larger proportion of upzoned houses
decreased in value relative to houses that
were not upzoned, with houses with intensity
above 0.55 (the 80th percentile) depreciating
when located in Zone 4 compared with Zone
1 (see Figure A4, available online). This is
unsurprising given that many of the dwell-
ings with joint land ownership are high
intensity (units and apartments) and further
corroborates upzoning having an immediate
depreciative effect on high intensity
dwellings.
16
Alternative pre- and post-treatment periods. We
also explore the extent to which our results
are sensitive to the selected pre-treatment
Greenaway-McGrevy et al. 971
and post-treatment periods. We consider
three different designs. The first examines
whether market participants anticipated
which areas would be targeted for upzoning
soon after the Local Government Act of
2010 required AC to generate a new unified
set of LURs (see section ‘Institutional back-
ground’), using 2007 to 2009 as the pre-
treatment period. The second examines
whether our findings are robust in a larger
sample that uses 2007 to 2012 as the pre-
treatment period. The third examines
whether houses prices adjusted immediately
after the draft AUP announcement in
March 2013, using 2014 to 2017 as the post-
treatment sample.
Columns (A) through (C) in Table A3
(available online) exhibit the results. Our
qualitative conclusions remain the same. The
coefficients on the upzoning dummies inter-
acted with intensity are negative and statisti-
cally significant at the 1% level (except in
two cases). Interestingly, the coefficient on
intensity is negative and statistically signifi-
cant when 2007 to 2009 is the pre-treatment
period, perhaps indicating that the redeve-
lopment premium was increasing across the
city as a whole over this longer sample
period.
Treatment spillovers. Upzoning may have real-
located development from non-upzoned to
upzoned areas, resulting in a demand spil-
lover that would cause our estimates to over-
state the price effects of upzoning. A
standard approach to control for spillovers
in difference-in-differences is to exploit var-
iation in the geographic distance between
treatment and control areas under the
assumption that the magnitude of the spil-
lover decreases with distance (Clarke, 2017).
We implement two robustness checks based
on this principle. We describe our main find-
ings below, but specific details and results
from the methods can be found in the
Supplemental Material.
First, we estimate the baseline regression
using a ‘doughnut’ sample.
17
The control
group consists only of Single House transac-
tions in townships that are located far from
the urban core of Auckland. These town-
ships contain no, or very little, land that has
been upzoned and thus are not subject to
the confounding demand-shifting spillover
within the township. Meanwhile, we restrict
our treatment sample to upzoned areas
within the urban core of Auckland. We find
that price appreciation rates conditional on
intensity are statistically indistinguishable
from those obtained from the baseline sam-
ple, suggesting that these spillover effects are
negligible, if present. Refer to Figure A6 and
the associated discussion in the
Supplemental Material.
Second, we implement the Clarke (2017)
method by constructing an indicator for con-
trol group (i.e. Single House) transactions
that are within a specified distance to a treat-
ment area. This proximity control dummy is
then included in the baseline regression and
is also interacted with intensity, so that the
upzoning treatment is measured relative to
control group observations that exceed the
specified distance to treatment areas. We use
both the 80th and 90th percentile distances
between Single House transactions and
upzoned areas as distance cut-offs, leaving
20% and 10% of the control sample, respec-
tively, to identify the treatment effects. The
regression results indicate no spillover effect.
Specifically, the proximity control dummy
indicator and the dummy interacted with
intensity are both statistically insignificant,
indicating that there is no statistical evidence
of a differential treatment effect between
proximate treatment and control groups
relative to distant treatment and control
groups. See Supplemental Table A5.
Placebo tests. We apply the placebo test pro-
posed by Chetty et al. (2009) by estimating
the same model over pre- and post-treatment
972 Urban Studies 58(5)
periods that altogether precede the AUP
announcement. These placebo tests serve
two purposes. First, they indicate whether
geographic variation in upzoning is related
with any omitted variables driving long-run
variation in house prices. Second, they tell us
whether the upzoning treatment was antici-
pated by the market prior to the draft AUP
announcement in 2013.
We focus on three placebo pre- and post-
treatment periods: 2005 to 2007 (pre) and
September 2011 to 2012 (post); 2004 to 2006
(pre) and September 2010 to 2011 (post);
and 2003 to 2005 (pre) and September 2009
to 2010 (post). These dates mimic the pre-
and post-treatment structure used in our
preferred specification, but the relevant peri-
ods have been pushed back in time by
between 5 and 7 years, so that the first draft
AUP announcement in March 2013 is
omitted altogether from the sample periods.
Columns (D) through (F) in Supplemental
Table A3 exhibit the results.
In all placebo samples the coefficients
on the upzoning dummies are mostly statis-
tically insignificant. The single exception is
the coefficients on the Zone 3 dummies in
the 2003–2005 to September 2009–2010
sample, which are significant at the 5%
level but incorrectly signed. From this we
may conclude that there is no d ifferential
effect of intensity on house price inflation
across the four zones prior to the draft
AUP announcement in 2013. This suggests
that the geographic variation in upzoning
is unrelated to any omitted variables driv-
ing l ong-run variation in house prices, and
that the market did not anticipate which
areas would be u pzoned prior to the first
announcement.
Conclusion
This paper examines the short-run impact
of a large-scale upzoning on house prices
and redevelopment premiums in Auckland.
Upzoning unambiguously increases redeve-
lopment premiums, as predicted by real
option theory, but the net effect of the policy
on house prices is mediated by the property’s
economic potential for site redevelopment,
with less-developed properties appreciating
relative to intensively developed properties.
These findings passed several robustness
checks and placebo tests.
Upzoning is increasingly advocated and
implemented in response to unaffordable
housing (Freeman and Schuetz, 2017;
National Public Radio, 2019), and our find-
ings have important implications for evalu-
ating the efficacy and impacts of upzoning
programmes. First, policy evaluation should
primarily be based on prices of targeted
intensive housing forms (apartments and
terraced housing), not those of underdeve-
loped, single house properties that are likely
to appreciate from upzoning. Second, there
are immediate distributive impacts of upzon-
ing on wealth within the population of
home-owning households, with owners of
underdeveloped properties realising an
increase in wealth relative to owners of
intensively developed properties.
We also find that properties that exceeded
a sufficiently high level of development
depreciated relative to similar non-upzoned
properties, indicating that upzoning can
have an immediate depreciative effect on
pre-existing high intensity housing.
Although this is consistent with the market
anticipating future construction of intensive
housing, concerns remain regarding the
capacity for upzoning to generate an
increase in construction sufficient to signifi-
cantly reduce house prices (Favilukis et al.,
2019) or improve housing affordability for
middle and lower income households
(Rodriguez-Pose and Storper, 2020;
Wetzstein, 2019). Thus, the long-run impact
of the AUP on house prices and affordabil-
ity hinges on a variety of additional factors
that merit further investigation. This
Greenaway-McGrevy et al. 973
includes the amount of intensive housing
construction generated; the pricing composi-
tion of that housing; distributional impacts
on housing accessibility and home owner-
ship across socioeconomic groups; and the
intersection and coordination of zoning with
urban transportation and development poli-
cies. These areas are beyond the scope of
this paper but are worthy potential future
research topics.
Acknowledgements
We thank Andrew Coleman, Arthur Grimes,
Jyh-Bang Jou, Will Larson, Kirdan Lees, Peter
Nunns, Chris Parker, Peer Skov, and seminar
participants at the Auckland University of
Technology, Otago University, the 2018 NZAE
meetings, and the joint MBIE Treasury workshop
in urban economics for helpful comments. We
thank Corelogic New Zealand for providing the
residential transaction dataset.
Author note
A previous version of this paper was circulated as
Greenaway-McGrevy R, Pacheco G and Sorensen
K (2018) Land use regulation, the redevelopment
premium and house prices. Working Paper 2018-02,
Auckland University of Technology, Department of
Economics.
Declaration of conflicting interests
The author(s) declared no potential conflicts of
interest with respect to the research, authorship,
and/or publication of this article.
Funding
The author(s) disclosed receipt of the following
financial support for the research, authorship, and/
or publication of this article: This work was sup-
ported in part by the Marsden Fund Council from
government funding, administered by the Royal
Society of New Zealand, under grant No. 16-
UOA-239. Sorensen gratefully acknowledges the
support of the Kelliher Trust PhD Scholarship.
ORCID iD
Ryan Greenaway-McGrevy https://orcid.org/
0000-0002-2822-9849
Notes
1. Freemark (2019a: 5) states: ‘Schill noted in
2005 that there has been insufficient study
of the effects of land use reforms on housing
supply and values, and that remains true
today’.
2. Freeman and Schuetz (2017: 229) state ‘[T]o
date no city has systematically upzoned large
shares of land as a mechanism to promote
affordability’.
3. Two elements of the AUP were not fully
operational at this time: (1) parts subject to
Environment Court and High Court under
the Local Government Act 2010, and (2) the
regional coastal plan of the PAUP, which
required Minister of Conservation approval.
4. Prior to the AUP, with infill and redevelop-
ment there was estimated capacity for
345,176 additional dwellings (Fredrickson
and Balderston, 2013: 15). After the AUP,
this figure was 1,076,267 (Auckland Council,
2017: 38).
5. DiNardo (2008) explains that quasi-natural
experiments are ‘serendipitous situations in
which persons are assigned randomly to a
treatment (or multiple treatments) and a
control group’, which permit analysis of out-
comes with respect to the particular treat-
ment. In our setting, the unit of observation
are properties and the treatment is upzoning.
6. AUs are non-administrative geographic
areas defined by Statistics NZ. Within resi-
dential urban areas, AUs are typically a col-
lection of city blocks or suburbs and contain
3000–5000 persons. For additional details
see http://aria.stats.govt.nz/aria/#Classifi
cationView:uri=http://stats.govt.nz/cms/
ClassificationVersion/cVYnMpeILgJRAY7E
7. Cross-leasing was an inexpensive alternative
to subdivision in NZ, whereby two or more
title holders jointly own the land underlying
the residential structures and lease use of the
land back to one-another at a peppercorn
rate.
974 Urban Studies 58(5)
8. AUP geographic vector data obtained from
the Department of Geography, University of
Auckland.
9. Because we only have the decade in which
the house was built, ages are approximated
based on the first year of the decade.
10. We use the location of the iconic ‘Skytower’.
11. 2006 census data. The next census is in 2013,
which is during the observation period.
Median incomes above NZ$100,000 are
truncated to NZ$100,000 for 19 of the
approximately 340 AUs.
12. We also considered the distance to the near-
est rail, ferry or express busway station
instead of distance to downtown. Our main
findings were unaffected but model fit
reduced marginally.
13. There was no uniform set of planning rules
for the region. Prior to amalgamation (see
section ‘Institutional background’) the seven
authorities used different plans, resulting in
approximately 99 residential zones.
14. Results not reported for brevity but are
available upon request.
15. The dummy is effectively interacted with
(log) land area because our dataset only has
land area for houses with exclusive owner-
ship of land on the title.
16. Without information on the entire stock of
dwellings we cannot use the model to esti-
mate the proportion of housing that
decreased in relative price from upzoning.
However, the model implies that 26.9%,
1.74% and 0.38% of the transacted houses
in Zones 4, 3 and 2, respectively, experienced
a decrease. However, selection effects mean
that this sample of transacted houses is
unlikely to be representative of Auckland’s
housing stock.
17. We thank an anonymous referee for suggest-
ing this approach.
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