# RECORD ddfdca9d11843f81e9f91bacfe723acfa0d83bbb
# TITLE: Energy Retrofitting for the Modern Heritage Enhancement in Weak Real Estate Markets: The Olivetti Housing Stock in Ivrea
# YEAR: 2022.0  VENUE: Sustainability  DOI: 10.3390/su14063507
# AUTHORS: Alice Barreca; R. Curto; Giorgia Malavasi; D. Rolando
# PAGES: 25  CANDIDATE TABLE PAGES (1-based): [15, 16]
# ABSTRACT: The enhancement of Modern Heritage buildings is nowadays a challenging issue as they are often degraded or abandoned and their historical value is not well acknowledged by potential buyers and their owners. Moreover, they are usually energy inefficient and obsolete, but investments for energy retrofit interventions are not always convenient, especially in socio-economic contexts characterized by weak real-estate market dynamics. This paper aims to study the influence of intrinsic and extrinsic characteristics on housing prices and, in particular, to understand whether elements of building cultural connotations or some housing green features are monetized by the real estate market. The UNESCO site “Ivrea, industrial city of the 20th century”, located in the weak real-estate context of the Eporediese territorial area, was selected as an emblematic case study and two data samples of property listings were built to perform spatial regression analyses. The results showed that the green features of housing, such as the heating type and the EPC level, have a greater influence on property prices than those characteristics related to the cultural connotations of a building, such as the Olivettian context. Therefore, the current incentive-based policies for energy efficiency can represent great opportunities that can be exploited both to preserve and to improve the condition of this valuable Modern Heritage.


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21 October 2026
POLITECNICO DI TORINO
Repository ISTITUZIONALE
Energy Retrofitting for the Modern Heritage Enhancement in Weak Real Estate Markets: The Olivetti Housing Stock in
Ivrea / Barreca, A., Curto, R., Malavasi, G., Rolando, D.. - In: SUSTAINABILITY. - ISSN 2071-1050. - 14:6(2022), p.
3507. [10.3390/su14063507]
Original
Energy Retrofitting for the Modern Heritage Enhancement in Weak Real Estate Markets: The Olivetti
Housing Stock in Ivrea
Publisher:
Published
DOI:10.3390/su14063507
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This article is made available under terms and conditions as specified in the  corresponding bibliographic description in
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MDPI


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Sustainability 2022, 14, 3507
14 of 24
Table 4. DS SEM regression results. (Source: Authors’ elaboration).
Regression Model: Spatial Error Model (SEM)
Dependent Variable: Listing Prices Logarithm (logTLP)
Independent Variables
Coefﬁcient
Std.Error
z-Value
Probability
LAMBDA
0.321
0.0456
7.043
0
CONSTANT
10.23
0.076
134.079
0
PT (Villa)
0.381
0.038
9.903
0
BC (Building Class-Economic)
−0.114
0.035
−3.281
0.001
BC (Building Class-Medium)
−0.065
0.031
−2.079
0.037
BC (Building Class-Noble)
0.135
0.047
2.862
0.004
FA (Floor area)
0.004
0.001
22.816
0
TR (Terrace)
0.105
0.025
4.126
0
US (Unit Status-Partially renovated)
0.271
0.038
7.105
0
US (Unit Status-Renovated)
0.466
0.042
10.962
0
EPC (Energy Performance Certiﬁcation -B and over)
0.162
0.066
2.45
0.014
HT (Heating Type-independent)
0.106
0.021
5.013
0
E (Elevator)
0.101
0.033
3.054
0.002
BN (Bathrooms number)
0.958
0.017
5.728
0
HD (Distance from the nearest highway exit)
−1.42 × 10−005
5.628 × 10−005
−2.517
0.011
RE (Retail services)
0.248
0.083
2.980
0.002
Number of observations
1154
R squared
0.664
Log likelihood ratio test
−521.72
0
Breush-Pagan test
103.897
0
AIC
1073.44
DIAGNOSTICS FOR SPATIAL DEPENDENCE FOR WEIGHT MATRIX
MI/DF
Value
Probability
Moran’s I
0.116
7.723
0
Lagrange Multiplier
1
43.885
0
Robust LM
1
5.746
0.016
Lagrange Multiplier
1
53.518
0
Robust LM
1
15.379
0.001
Lagrange Multiplier
2
59.264
0
The analysis of the impact of the housing green features highlighted that high EPC
levels (EPC = B and over) and the heating type (HT = independent) signiﬁcantly affect
LP, conﬁrming that, as demonstrated in other studies [32,37,62], the energy efﬁciency is a
noteworthy feature with an increasing inﬂuence in the real estate market.
Finally, it is worth mentioning the inﬂuence of the extrinsic characteristics, such as the
presence of retail services (RE) and the distance from the nearest high-way exit (HD).
5.2. SS-Ivrea
Focusing on the city of Ivrea, the real estate market dynamics were analyzed in relation
to both some property features (including the “green” ones) and to the presence of the site
“Ivrea, industrial city of 20th century”. Therefore, the two variables “distance from the
UNESCO site (UD) and the “building Olivettian connotation” (OL) were considered in
the model since the UNESCO site will become a relevant point of interest for tourists and
citizens, even if the weak socioeconomic context may not foster this process.
Additionally, in this case, the logarithm of total listing price (logTLP) was used as
a dependent variable and a set of intrinsic and extrinsic features, selected by means of a
“foreword” stepwise method, were assumed as independent variables. Additionally, in this
case, the spatial autocorrelation tests indicated the Spatial Error Model (SEM) regression as
the most suitable model.
The regression results (Table 5) showed that this model is able to explain 62% of the
price variation (R squared = 0.620).


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Sustainability 2022, 14, 3507
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Table 5. SS SEM regression results. (Source: Authors’ elaboration).
Regression Model: Spatial Error Model (SEM)
Dependent Variable: Listing Prices Logarithm (logTLP)
Indipendent Variables
Coefﬁcient
Std.Error
z-Value
Probability
Lambda (TLP)
0.246
0.1
2.451
0.014
CONSTANT
10.528
0.107
98.02
0
BC (Building Class-Noble)
0.35
0.078
4.454
0
FA
0.005
0.001
12.813
0
US1 (Unit Status-Partially renovated)
0.237
0.073
3.248
0.001
US2 (Unit Status-Renovated)
0.398
0.085
4.68
0
HT (Heating Type-independent)
0.135
0.046
2.933
0.003
PG (Private Garden)
0.152
0.065
2.343
0.019
OL (Building Olivettian Connotation)
−0.174
0.066
−2.658
0.008
UD (Distance from the UNESCO site)
−9.921 × 10−005
−3.49 × 10−005
−2.845
0.004
EPC (Energy Performance Certiﬁcation-B and over)
0.311
0.14
2.219
0.027
Number of observations
248
R squared
0.62
Log likelihood ratio test
−80.169
0
Breush-Pagan test
104.524
0
AIC
180.338
Diagnostics For Spatial Dependence For Weight Matrix
MI/DF
Value
Probability
Moran’s I
0.0831
2.7892
0.005
Lagrange Multiplier
1
6.206
0.013
Robust LM
1
1.432
0.231
Lagrange Multiplier
1
5.471
0.019
Robust LM
1
0.697
0.403
Lagrange Multiplier
2
6.903
0.031
In line with the results obtained by the previous model, the building category (BC = noble),
the unit status (US = renovated), the heating type (HT = independent) and high EPC levels
(EPC = B and over) are characteristics that can considerably inﬂuence TLP.
Unlike the previous result, this regression analysis also highlighted that the presence
of a private garden (PG) positively affects TLP; in this regard, it is worth mentioning that
in Ivrea there are several villas and detached houses that include their own garden.
Focusing on the inﬂuence of the UNESCO site, it is interesting to notice that the
distance from the UNESCO site (UD) has a negative coefﬁcient: thus, the greater the
distance from the site, the lower the property TLP. This is an important result which
conﬁrms that this important and strategic point of interest could progressively increase its
positive inﬂuence on the Ivrea real estate market.
On the other hand, the variable “Olivettian connotation” (OL) of buildings presents
a negative coefﬁcient, which means that the Olivettian connotation is not positively rec-
ognized by the real estate market. This result is in agreement with recent studies that
demonstrated that the architectural quality is not easily acknowledged by buyers and
sellers [8,63]. In Ivrea, in fact, even if the Olivettian housings often represent valuable
examples of Modern Heritage, they are classiﬁed as “economic” buildings and thus de-
valued. These buildings represent the legacy of the Olivetti company, but even if their
tangible and intangible value is relevant for architectural, social and political reasons, it
does not positively inﬂuence the property price variation. On the contrary, the building
category (BC), the unit status (UT) and some green features have a stronger inﬂuence on
property prices.
Therefore, it is possible to afﬁrm that the green features (of which the EPC is a
proxy) are even more recognised by the real estate market than the architectural or
historical values.


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Sustainability 2022, 14, 3507
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5.3. Prediction of Property Values after Energy Class Upgrade
In order to simulate a potential increase in the property price after a hypothetical
energy class upgrade deriving from possible energy retroﬁt intervention, the results of the
last regression were used to estimate new real estate market values of the asset collected
in the SS. This operation aimed not only to understand the potentiality of an energetic
optimization on the Modern Heritage, but also to evaluate if the costs of intervention could
be covered by the sale of the properties.
Firstly, only the listing price of the assets with the lowest EPC levels (E-F-G, 446 obser-
vations) were estimated; this operation was performed to compare the model predicted
values to the observed listing prices. The results highlighted an acceptable discrepancy in
the prediction of the listing price, which represents the error rate of the model.
The estimated property prices were calculated on the basis of the predicted values of
the SEM model calculated by GeoDa, assuming the simpliﬁed following formula [45,60,64]:
ELP (CEL) = (λTLP + 10.528)−1 (0.35 BC + 0.005 FA + 0.237 US1
+ 0.398 US2 + 0.152 PG −0.174 OL −9.921−005 UD).
where: ELP (CEL) is the predicted value of the Total Listing Price with the current EPC
level of the SEM model (Table 5) expressed by its logarithm, λ stands for added spatial
error coefﬁcient; BC, FA, US1, US2, PG, OL, UD are the variables introduced for each of the
analyzed characteristics.
Subsequently, a second estimation was performed to understand whether an energy
retroﬁt intervention, which would change the lowest EPC levels (“E-F-G”) to the highest
ones (“B and over”), could lead to an increase in the listing prices. The energy upgraded
property price was estimated by changing the marginal coefﬁcient related to the lowest EPC
levels with the one related to the highest EPC levels, according to the following formula:
ELP (ELU) = (λ TLP + 10.528)−1 (0.35 BC + 0.005 FA + 0.237 US1 + 0.398 US2
+ 0.152 PG −0.174 OL −9.921−005 UD + 0.311 EPC)
where: ELP (ELU) is the predicted value of the Total Listing Price with the EPC level
upgraded of the SEM model (Table 5) expressed by its logarithm, λ stands for added spatial
error coefﬁcient; BC, FA, US1, US2, PG, OL, UD are the variables introduced for each of
the analyzed characteristics, with the addition of the calculated marginal coefﬁcient of
upgraded EPC level (“B and over”).
Therefore, the results deriving from the two estimations were compared. Figure 6
shows the comparison between the ﬁrst estimation with Total Listing Prices at the current
energy level and the same cases but with a hypothetical upgrade in energy class maybe due
to a general intervention such as walls and roof insulation and the replacement of windows.
The difference between those two estimated prices is positive for 93% of the observations,
thereby providing evidence of the cost-effectiveness of retroﬁtting houses, and it can be
considered as a starting point for the conservation of these residential buildings, especially
those located in the Olivetti’s residential districts (Figure 6).
Initial evidence can be found in Canton Vesco; by looking at the maps, it is possible to
see the retroﬁt intervention effects on the listing prices. In Figure 6a, values of this district
fall into the lowest Jenks range, while in the map in Figure 6b the estimated listing prices
fall into the highest price range. In the Historical Centre of the city and in the UNESCO
Site, prices rise from a mean of 110,000 Euro/sqm to 118,000 Euro/sqm and by observing
the map it is possible to see that prices increase not so much to the higher range but to the
intermediate one. In particular, the number of apartments with the lowest observed listing
prices is 191, while the number of those with an ECP level from B is 176. Furthermore,
there is also a considerable increase in the dwellings with the highest values, i.e., in the ﬁrst
image only one case is observed, but in the second there are 34.