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TizianoDalla Mora | Francesca Cappelletti | Fabio Peron |
Department of Designand Planning inComplex EnvironmentsUniversity
IUAV of Venezia,Venezia, Italytiziano.dallamora@iuav.it | Department of Designand Planning inComplex EnvironmentsUniversity
IUAV of Venezia,Venezia, Italyfrancesca.cappelletti@iuav.it | Department of Designand Planning inComplex EnvironmentsUniversity
IUAV of Venezia,Venezia, Italyfabio.peron@iuav.it |
PiercarloRomagnoni | Fred Bauman |
Department of Designand Planning inComplex EnvironmentsUniversity
IUAV of Venezia,Venezia, Italypierca@iuav.it | Center for Build EnvironmentUniversity of California,
BerkeleyCalifornia, USAfbauman@berkeley.edu |
As it happens in several Italian cities,
the downtown of Treviso, in North East of Italy, is characterized by the
presence of historical buildings. Ca’ S. Orsola
building is a typical example: the building is located very close to the city
Cathedral. Originally it was a convent: it was the old seat of Polish Institute
of the Orsoline Sisters. Now it is a building listed
by Historical and Architectural Heritage Superintendence of Veneto Region.
The building was inhabited until 2000 and
during the time it keep intact the original structure and architectural
distribution. Then it was bought in 2007 for acting a deeply renovation and
converting it in a prestigious residential building; this renovation has been
completed in 2012. The whole building (Figure 1) is a gross volume of 6 300 m³ and an area of 4 500 m².
Figure 1. General view of the building a) before and b)
after the intervention. |
At the beginning of construction phase the
structure revealed a quite ruined state of conservation: walls are crooked and
presented different solutions, moisture affected wooden elements in the floors
and in the roof. There was a heritage architectural restriction about the
external envelope. Specific goals of renovation project were:
·
to achieve the A class energy
classification according to Italian regulations;
·
to consolidate and to reinforce
the building structure;
·
to improve the indoor thermal
and acoustic quality;
·
to transform it in a
prestigious residence with all comforts.
The building refurbishment was developed
with a particular regard on thermal insulation of the building envelope and
special attention has been paid to the mechanical ventilation and the renewable
energy utilization (both solar thermal and photovoltaic system).
The adopted requirements follow the
legislative references as stated in national Italian laws before the 2012.
Building envelope before renovation
presented a traditional construction system, based on bearing masonry with
covered solid bricks. The floor had a wooden structure, while the ground floor
leaned directly on soil. The roof is made of hollow tiles sheets with a wooden
structure and a lightweight ceiling slab (Figure 2).
Figure 2. Building envelope before renovation: a) crooked
walls; b) demolished partition walls left and used as a substrate; c) beam support in
the perimeter wall. |
The windows frames were made of wood and
the windows used to have a single glass. There is no insulation in the external
walls, roof and floors (Table 1).
Table 1 Thermal characteristics of the building elements.
Element | Area (m²) | U-value before renovation
| U-value after renovation |
Facade | 1 300 | 0.90 | 0.18 |
Ceiling | 508 | 1.65 | 0.788 |
Windows, doors | 140 | 2.70 | 1.948 – 2.035 |
Roof | 508 | 1.09 | 0.158 |
Originally, no heating and cooling systems
were installed. Heating was provided by a fireplace, also used for cooking,
occasionally an electric heater or portable fan coils was placed in any room.
The domestic hot water was supplied by electric heaters with storage tank; no
ventilation system was present.
If we analyse this case study in terms of
environmental sustainability, there are several challenges ahead. A first
challenge was addressed at the level of structural consolidation then at the
level of energy and indoor quality.
Technologies measures aimed to achieve an
energy class as proposed by the Italian legislation before 2014; several design
topics were adopted among which high insulated windows, high level of opaque
walls insulation, mechanical ventilation system with heat recovery, solar
thermal panels and PV systems, water to water heat pumps and chillers.
The first step has been taken the measures
to consolidate the building structure. Subsequently a detailed study on thermal
and acoustic bridges has been developed with the aim to improve the indoor
thermal and acoustic quality.
In the external walls the insulation is
placed on the inner part (Figure 3) and this solution meet the requirements of the Superintendence of
Veneto Region, preserving the existing materials and the external architectural
identity of the building. Specifically, two types of insulating are used: an
expanded polystyrene (EPS) foam, placed directly on masonry, and a rigid
mineral wool panel with a plasterboard cover. Roof was replaced with a new
wooden structure and it was insulated with wood fibre and water tight covering.
All existing windows are replaced with a low-energy double layer ones within
wooden frames.
Figure 3. Insulation on a) internal and b) external walls. |
About technical systems, the HVAC
generation system is a water to water centralized heat pump/chiller. The
underlying well is the hot/cold water source and internal comfort is achieved
exploiting a radiant system (Figure 4) installed in the floor together with a dehumidification system for
the summer period.
Figure 4. Radiant system: a) collectors and b) TNT underflooring above system. |
For heating and cooling the system adopted
is a 32 kW heat pump with a distribution by radiant floor system; another
heat pump (20 kW) is installed for domestic hot water requirement (DHW);
mechanical ventilation (Figure 5) is provided by a system with heat recovery box (95% efficiency).
Figure 5. Mechanical ventilation system: ducts and Heat
Recovery. |
Renewable energy systems have been
installed after renovation: thermal solar panels for DHW production (20 m²)
are located in vertical position and a photovoltaic power plant (18.85 m²)
producing 3 300 kWh of total annual energy. These panels are
installed on the roof and oriented to the south.
Energy needs values before renovation have
been evaluated by means of dynamic simulation: the results are showed for
comparing thermal the different conditions after and before the retrofit
measures. It should be stressed that values for DHW need already include the
solar thermal contribution and the amount of renewable energy was zero before
renovation (Table 2).
Table 2. Energy savings and CO2 reduction.
Energy need | Before renovation | After renovation | Saving | |
Heating | kWh/m²y | 342.7 | 42.3 | 88% |
DHW | kWh/m²y | 44.4 | 33.6 | 24% |
Electricity | kWh/m²y | 45.0 | 20.0 | 56% |
Total | kWh/m²y | 432.1 | 95.9 | 92.5% |
Energy label | G | A+ | ||
Carbon emissions | kg CO2Eq /m²y | 29.8 | 5.8 | 81% |
Construction costs of renovation (Table 3) exclude
the costs for heating and DHW equipment, so the costs are related to the
purchase of the area, charges, interest, taxes.
The contribution of renewable energy
resources is given in 6.56 kWh/m²y: calculation and monitoring gives a
production of about 3 300 kWh for photovoltaic system and 8 500 kWh
for solar thermal.
Table 3. Renovation costs.
Costs | EUR | EUR/m² |
Craftsmen | 2.94 million | 1 463.41 |
Consultants | 130 000.00 | 64.71 |
Electrical and Plumbing | 700 000.00 | 348.43 |
Total construction | 377 million | 1 876.56 |
Thermal solar and PV
system | 32 000.00 | 15.92 |
NPV | 13 Years |
The major benefit given by renovation
measures is obtained evaluating the energy saving: the energy need for heating
was 432.1 kWh/m²y, including heating, DHW, ventilation systems. The
interventions allowed to reduce the Energy need by 93%. The Energy class
improves to G to A+.
At the same time, the indoor climate was
improved due to the upgrade of the control of indoor temperature and humidity
without relevant energy costs. The standard energy performance for new
buildings in Italy has been achieved by several factors such as the reduction
of losses through the walls insulation, roof and the installation of new
window. The reduction of the thermal bridges allows to eliminate related
condensation problems and also the mechanical ventilation is balanced with heat
recovery and with a carefully adjusted supply temperature. From economic point
of view, renovation of existing buildings, especially if listed, is too much
expensive than standard, because it needs specialized operations and the
preliminary count evaluation is upset during the construction phase. After intervention,
however, market value increased for this property and also for the surrounding
area: in this case study all apartments have been sold by the end of the
construction phase (Figure 6).
About decision process during building
phases, the investment costs were incurred by the contractor, that is also the
owner: in this particular situation themes such as sustainability and energy
retrofitting were understood and applied. The major overcome barriers were
essentially related with the bureaucracy for obtaining the permission by
Historical and Architectural Heritage Superintendence of Veneto.
Figure 6. The residence after intervention: a) Courtyard
from west perspective; b) Typical living room in a dwelling. |
After the retrofit intervention it’s
possible to underline also non-energy benefits, rather factors that can be
brought back to social and economic aspects in the long term. For example, this
radical renovation transformed this historic building in a prestigious and
comfortable residence. A better living conditions is enriched with more
qualified living spaces and privacy to the occupants are ensured by a reached
acoustic first class according to national standard UNI 11367. The
improved structural conditions in an uninhabited and listed building
implemented a seismic consolidation and an aesthetical improvement returned the
identity of the original building and increased the market value.
The
proposed renovation is aimed to redefine the indoor environmental quality with
a particular attention to the energy and acoustic targets. Moreover, as
requested by Italian laws, the building structures must be certified by seismic
point of view.
The adopted
measures for envelope and technical system, as low-e energy glasses, the high
performance insulating layer, the installation of a mechanical ventilation
system with heat recovery, the integration of solar panels for DHW, allowed to
achieve that the apartments of the block have been certified in A Class.
Living
environmental quality is assured by the use of indoor materials with low
harmfulness and because of the installation of underfloor winter heating and
summer cooling with humidity control. Renovation measures decreased global
energy consumption, reducing up to 90%; the use of renewable (solar and
photovoltaic systems) contributed to minimized energy consumption.
A prestigious location, a renovated
historic building with the most innovative technical solutions made a safe and
long-lasting investment.
Special thanks belong to:
CazzaroCostruzioni Staff for interest in
collaboration on this project.
Ing. Vincenzo Conte for sharing the necessary data about heating system.
Apartment inhabitants for cooperation
during in-situ inspections and interviews.
[1]http://www.
http://iea-annex56.org/
[2]CASA&CLIMA, n.47, “Storico, antisismico e
in Classe A”, pg. 36-44, Quine Business Publisher Edition, 2014.
[3]UNI 11367, Building
acoustics - Acoustic classification of building units - Evaluation procedure
and in situ measurements, 2010.
[4]UNI TS 11300, Energy
performance of buildings. Part 1: Evaluation of energy need for space heating
and cooling, 2014.
[5]UNI TS 11300, Energy
performance of buildings. Part 2: Evaluation of primary energy need and of
system efficiencies for space heating, domestic hot water production,
ventilation and lighting for non-residential buildings, 2014.
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