Passive House Object Documentation

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1 Passive House Object Documentation 3 stores, 9 units multifamily building in Lonato, Brescia, Italy Project team Architecture: Arch. Angiolino Imperadori Structures and tech. services: Ing. Giovanni Ziletti Sustainability and energy : Dott. Sergio Rossi This multifamily building has been built by Coop Casa SC in Lonato, Brescia, Italy. The nine flats are rented to low income families by mean of social housing contracts. The project has been co-funded by local authorities within a social housing support scheme. 3 floors, 3 units on each floor; first 2 floors are concrete + bricks construction and last floor prefabricated wood construction. The building is partly on the ground, partly on an underground basement (not heated). Technical room with centralized DHW system (heat pump) is placed on the roof. The building has been occupied since Special features: Centralized photovoltaic system 20 kwp for shared building services U-values PHPP Annual External walls (average): 0,14 W/(m 2 K) heating demand: 13 kwh/(m 2 a) Basement ceiling: 0,15 W/(m 2 K) Floor over the ground: 0,12 W/(m 2 K) PHPP Primary Roof: 0,07 W/(m 2 K) energy demand: 120 kwh/(m 2 a) Windows (average): 0,93 W/(m 2 K) Effective heat recovery: 76,5% Pressure test n 50 : 0,6 1/h 1

2 Summary Short description of the construction task...3 Pictures of elevations from all accessible sides...4 South facade...4 West facade...4 East facade...4 North facade...5 Sample pictures of the interior...5 Staircase...5 Living room...5 Cross section of the implementation plan...6 Floor plans...7 Construction details of the Passive House envelope and building services...9 Construction including insulation of the floor slab or basement ceiling with exterior and interior wall constructions...9 External walls...10 Construction including insulation of the roof or the attic floor with exterior and interior wall connections Cross sections of windows including installation sketch (to a recognisable scale) type of window/ specific values...13 Description of the airtight envelope; documentation of the pressure test...16 Ventilation...18 Heat supply...21 Heating system...21 Hot water...23 Brief report of important PHPP results...25 Construction costs (construction and building services)...27 Year of construction...28 Information on the architectural design...28 Information on the building services planning...28 Information on the structural physics planning, if applicable...29 Information on the structural analysis planning, if applicable...29 Experiences (user opinion, actual consumption values)...29 References to existing studies/ publications on this project

3 Short description of the construction task The task for this project was to develop and test a concept for multi storey residential buildings with zero energy balance, suitable for North Italy. The construction costs as well as maintenance costs had to be affordable. The objective has been achieved by: combining passive design techniques to contain heat losses in winter and solar gains in summer, maximizing PV integration, adopting thermal system to provide heating and cooling with simple operation and maintenance. The concept has been summarized in a code of practice named Casa Light and it has been applied to a 2 buildings project for total 18 flats cooperative housing project in Lonato (Brescia, Italy). The 2 buildings are basically identical, but only the south block has been certified with the PH Quality Certificate (the project is published on the Passive House database with ID 2416). The most relevant difference is that the south building top floor has been constructed using wooden prefabricated elements, while all the other components were masonry walls and external insulation cladding. The wooden structures allow for higher thermal insulation. Construction works were completed in 2011 and the apartments have all been assigned in Consumptions and production data are currently being monitored within the EU cofunded project esesh - in which advanced ICT solutions for energy awareness and management are developed and tested. The results from the monitoring activity will be available from mid April 2013 on database with the ID Lonato Casa Light HC2.020.Lonato E6 E7. 3

4 Pictures of elevations from all accessible sides South facade: from this picture it is possible to see some of the sun screens in use. The bigger windows are concentrated on the south facade. In this climate, windows area should be not too large in order to avoid overheating problems during summer months and external shadings are always needed. West facade: trees has been planted on the west side. In few years time they will provide effective shading on the west facade during summer months. East facade: like the west facade, the design of east facade is very simple with small windows. 4

5 North facade: also the north facade is simple and compact. An exception is provided by the balconies of the kitchens, which in summer are meant to be used as a space where to consume lunch or spend family time. Sample pictures of the interior Staircase: the staircase is wide and with abundant natural light. Ventilation air ducts, water distribution pipes and the evaporated-gas pipes of the heat pumps units are installed under the ceiling of each floor, which is then closed by a false ceiling. Living room: the dominant component of the living room in all the apartments is the large window, which is composed by a glazed door and a fixed window. It is designed to contribute in winter sunny days to the passive heating of the apartment. 5

6 Cross section of the implementation plan The cross-section of the building shows the compactness of the heated volume. Each floor repeats the same dwelling typology. There is a common staircase on the north side of the block, where there is also a lift and the distribution of technical services. The staircase connects also the underground floor, where there is the car park and a small storage room for each dwelling. The staircase gives also access to the technical room on the roof, where there is the centralized hot water system. The 2 largest dwelling of each floor have windows on 3 sides, while the smaller, central dwellings, only toward south. On the cross sections have been signed the construction details which are described in the following chapters. 6

7 Floor plans Each floor has three dwellings, one with three rooms plus kitchen and bathroom, one with two rooms plus bathroom, one with three rooms plus kitchen and 2 bathrooms. The main 7

8 exposition is south, where there are the largest windows and a continuous balcony in front of it. The volume within the dwellings is insulated on all sides, including the walls toward the staircase which is not heated. The staircase is also thermally insulated towards the outdoor. For the north balconies, thermal bridges have been limited using Shöek elements. The long south balconies are supported on the south side by small concrete pillars, while they are anchored to the construction by mean of specially designed metal shelves. 8

9 Construction details of the Passive House envelope and building services Construction including insulation of the floor slab or basement ceiling with exterior and interior wall constructions There are 2 types of floor: floor on the ground and floor on the basement (not heated). The floor on the ground is insulated with a 20 cm EPS layer, than another 20 cm layer with the concrete beams and EPS boards in between, with on top a 5 cm reinforced concrete layer. To cut the thermal bridges, the foundations walls and pillars are clad with EPS boards 5 cm thick, while the divisional walls inside the dwellings at the first floor are placed on top of the reinforced concrete layer. The floor on the basement has been constructed using EPS preformed boards which served also to form the concrete beams in opera. It is interesting maybe to note that the max. Commercially available continuous insulation layer of this product is 8 cm. We have been able to increase this layer to 20 cm by using EPS boards which were meant for bigger beams, filling the bottom of the gap with EPS in order to create a continuous layer of 20 cm. This layer is continuous with the 20 cm layer of the floor on the ground. 9

10 External walls For the first 2 floors above the ground, the typical reinforced concrete frame structure has been used. The space between pillars is filled with a masonry wall of perforated bricks 25 cm thick, with plaster on the inner side. The wall is clad with a layer of graphite-eps panels, 15 cm thick, finished with plaster The top floor is made with prefabricated wooden elements, frame in laminar wood, filling in mineral wool, inner and outer panels in OSB for a total thickness of 20 cm. On the outer side of the wall, the cladding in graphite-eps is continuous with the floors below. On the inner face of the prefabricated component, there is the water vapour barrier, an air gap of 4 cm and than a curtain made of mineralized wood-cement boards plastered on the inner face. 10

11 Construction including insulation of the roof or the attic floor with exterior and interior wall connections The roof has been built with prefabricated wooden elements similar to those used for the walls of the second floor, but thicker (28 instead of 18 cm). On the inner side, the water vapour barrier, a layer of mineralized wood fibres panels plastered on the inside. On top of the wooden structure, EPS (21,5 cm average) and XPS (5 cm) boards have been used to add insulation. EPS boards where cut with an angle, in order to provide the right inclination to allow for rain water drainage: an inexpensive solution which save space, as normally in flat roofs this is achieved with a concrete layer. 11

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13 Cross sections of windows including installation sketch (to a recognisable scale) type of window/ specific values In this project the windows are probably the most valuable (and expensive) component among the others. Windows are a vital component also in this climate, as they have to provide enough sun light, insulate from the cold in winter and prevent overheating in summer. The windows used have a laminar wooden frame, 92 mm thick, with Al elements coating on the outer side (only the most exposed parts of the frame are covered). There is triple glazing with gas filling and selective coatings. To allow for a neat, and precise installation, a prefabricated window reveal system (provided by the same window manufacturer), which is equipped with all the relevant insulation parts in order to cut thermal bridges and provide adequate air tightness. To facilitate the sealing of the window reveal and the masonry wall, the wall was plastered before the installation. The gap has than been filled with PU foam and specific tapes has been used to maximize air tightness. This reveal system includes also the box where the window obscuration system is installed. The obscuration system is a PVC roll up system, very common in all the Country in multi apartments buildings, although normally is a separated non insulated element installed on the inside of the exterior wall. This is typically a very critic element for thermal bridges, air tightness and acoustic insulation, but the solution adopted helps to overcome these problems still preserving the local style. 13

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15 Windows manufacturer: Südtirol Fenster; model Genius 92. Prefab. Insulated reveal manufacturer: Südtirol Fenster; model ISO-bloc. Uf = 0,92 W/(m 2.K) Ug = 0,60 W/(m 2.K) Solar factor g = 48% Glass spacer Chromatec (stainless steel), Psi spacer 0,053 W/(m.K) Psi installation: 0,030 W/(m.K) 15

16 Description of the airtight envelope; documentation of the pressure test The air-tightness limit value n 50 has been verified (blower door test EN standard, method A) and satisfied in all the 9 units. The task has been challenging, especially because with such small volumes a better air tightness per m 2 of the envelope is required. The test has been performed twice for each dwelling. The first test was just after the installation of the windows, in order to be able to identify and correct imperfections in time. The test was repeated once again in each dwelling at the end of construction works in order to assess the n 50 value for the PHPP calculation. The following table resume the final results: Unit Net heated area N ground floor 67,0 0, ground floor 42,3 0, ground floor 77,3 0, first floor 67,0 0, first floor 42,3 0, first floor 77,3 0, second floor 67,0 0, second floor 42,3 0, second floor 77,3 0,6 In the wooden floor, the external cladding with plaster offers a first protection to the wind, while the ultimate air barrier is provided by the water vapour barrier. In order to ensure continuity of the air tightness layer, tape has been used to fix the barrier to the building elements and 2 overlapping stripes. Specially designed neoprene sealing have been used between the window reveal system and the walls. Butilic sealing tape has also been used as well as PU foam. The blower door was installed in the entrance door of the flat. 16

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18 Ventilation Figure 1 The ventilation plan of one of the dwellings Each dwelling has its own ventilation system with heat recovery type Zehnder Comfoair 140. Model η HR (PHPP) η HReff (PHPP) Max flow Electricity (%) (%) (m 3 /h) (Wh/m 3 ) Comfoair The Comfoair 140 has an automatic bypass which is operated on the bases of the extracted air from the dwelling temperature and fresh air from the outside temperature, and a preset value. When the preset extracted air temperature is greater than the preset temperature and the ambient temperature is smaller than the extracted air temperature, the bypass is activated in order to cool the indoor air (so called free cooling). The three ventilation units of each floor are installed in the staircase niche, in order to facilitate maintenance operation such as filters cleaning and change. An intuitive, manual control device with 4 positions is installed inside the dwelling and is operated directly by the user. 18

19 Figure 2 The Zehnder Comfoair 140 units before being connected. The units are connected to the outdoor with metal air ducts of 125 mm diameter. The ducts run just behind the ventilation units and the fresh air intake/ exhaust air outlet are placed on the roof. A regulation valve is placed on both ducts, just before the ventilation unit, in order to allow for precise balancing. Balancing has been made separately for each ventilation system, using an Airflow Diff balometer before taking the building in use. Figure 3 The baometer used for the initial balancing of the systems The connection to the dwelling is made with 125 mm diameter metal ducts, insulated with 19

20 60 mm mineral wool. In the length of duct between the ventilation unit and the dwelling, a noise silencer is installed on each duct. Figure 4 The noise silencers are installed between the ventilation unit and the dwelling. A double ceiling has been applied to close the duct distribution. Inside the dwelling, the ducts have a smaller diameter after division. Regulation valves allow setting the exact flow in each room according to design: Dwelling size (m 2 ) 0 (m 3 /h) 1 (m 3 /h) 2 (standard) (m 3 /h) 3 (m 3 /h) 67,0 - standard 30% 70 standard + 30% 42,3 - standard 30% 50 standard + 30% 77,3 - standard 30% 80 standard + 30% Filters, intake duct work: there is a G2 filter on the intake vent on the roof, which is common to all the ducts. In the ventilation unit there is a G4 before the heat exchanger and an F6 filter after the heat exchanger. Filters, exhaust air duct work: there is a G4 filter in the ventilation unit before the heat exchanger. In addition, the kitchens exhaust air vents are equipped with a G3 metallic filter, which can be washed by the user. 20

21 Heat supply Heating system Figure 5 Heating system plan Each dwelling has an air to air heat pump, which can be used also in summer to provide additional cooling. The internal unit is hanged to the roof of the distribution room of the dwelling. The extraction is placed under the internal unit, while the heated air is distributed to all rooms by mean of metal ducts. The heat pump type is Dykin FDXS25E for the 3 smaller dwellings, and Dykin FDXS35E for the other 6 dwellings. The seasonal average COP used in the PHPP calculation is 3,0. 21

22 Figure 6 The internal unit of the heat pump; it is clearly visible the battery of the heat pump, in front of which will be mounted the plenum with the derivations to each room The external unit of the heat pump is installed on the flat roof. Figure 7 The external units are placed on the flat roof; the evaporated-gas pipes have been covered with extra insulation and an aluminium cover. In addition to the heat pump, in every bathroom is installed an additional electrical radiator, which is used as a backup heating source. 22

23 Hot water Figure 8 Centralised sanitary hot water system plan Hot water is produced with a centralized system composed of an air to water heat pump compact unit (CLIVET WBAN41) and of a 1000 l puffer storage (IDM Hygienik 1000/50) with heat exchanger for instant production of hot water). The storage is installed in the technical room (thermally insulated) on the roof, while the heat pump compact unit is placed just outside the technical room. The original idea was to have only electrical appliances in the building, in order to maximize the self-consumption of electricity produced by the photovoltaic system, which allow for a better payback than feeding into the grid. In terms of primary energy, there is no big difference between producing hot water via heat pump or high efficiency gas boiler (heat pump should have a smaller consumption of primary energy compared to gas boiler). Figure 9 Heat pump: the compact unit is installed on the roof, 2 meters from the technical room where is installed the water puffer storage 23

24 Figure 10 Water storage: the picture shows the heat exchanger for instant production before the application of the thermal insulating case; the pictures shows also the electronic control unit 24

25 Brief report of important PHPP results The only type of energy consumed in the building is electricity. The calculated consumption per unit of heated net area are as follow: Heating: 3,9 kwh/m 2.a Hot water: 7,2 kwh/m 2.a Auxiliary electricity (inc. Ventilation): 7,2 kwh/m 2.a Household appliances: 28,0 kwh/m 2.a Total: 46.3 kwh/m 2.a (which multiplied by 2,6 gives 120 kwh/m 2.a of primary energy) 25

26 Household appliances account for about 60% of the total demand. This confirms that in a passive house, the consumption for household appliances is the prevalent consumption type. In this calculation, the contribution of solar PV has not been considered. The energy produced by the photovoltaic system has been calculated is 39.3 kwh/m 2.a, equal to the 85% of the total demand. Please note: the heating load has not been calculated (10 W/m 2 is the value assigned by default by PHPP) due to the lack of appropriate local climate data. 26

27 Construction costs (construction and building services) The costs for the 2 buildings are as follow: Construction works and materials Windows and entrance doors Photovoltaic Connection to electricity and water grid Contract costs Design and other technical costs TOTAL The net heated area of the 2 buildings is 1119 m 2, which gives as a result a total cost of /m 2. Of this, 115 /m 2 are for the photovoltaic system, which actually pays for itself because of the feed in tariff The gross commercial area of the 2 buildings is 1961 m 2, which gives as a result a total cost of 962 /m 2. Of this, 66 /m 2 are for the photovoltaic system. The gross commercial area, according to the local definition, includes 100% of heated area, 35% of balconies, 50% of deposits, 60% of car boxes and 25% of car 27

28 Year of construction The construction works started in 2010 and finished in Dwellings were assigned only during 2012 Information on the architectural design The architectural design has been oriented to achieve best performance in terms of: energy consumption, internal comfort and construction costs. The Passive House Planning Package (edition 2007) has been used along all the phases of the design in order to optimize it. Some of the most relevant architectural solutions adopted are: - orientation of the building with main facade towards south; originally a single block of 18 dwellings was planned, oriented along the axe north-south; this has been changed opting for 2 separate blocks of 9 dwellings each, oriented on the axe east west - compactness of the heated volumes, continuity of the thermal insulation and of the air tightness elements - orientation of the windows to maximize solar gain/ protection in the different seasons This project has a component of demonstration of how to make a passive house suitable for the local climate. For this reason, only the south block has been certified Passive House, while the north block, which suffers of minor solar gain in the winter, was intended to be used as reference. In the end, the differences between the 2 blocks are neglectable. The main one is that external walls and roof of top floor of the certified block has been constructed using wooden elements, which were able to provide a better thermal insulation. Information on the building services planning A passive house doesn t require a traditional heating system. This is probably true also for this project but, being a multifamily, cooperative housing project, there was an explicit requirement of the housing company to make sure that the heating system would have been able to provide enough heat independently of the usage habits of the users. Each of the 2 buildings has a 20 kwp solar PV system. The system is installed on the roof, using special metal carpentry directly anchored to the structure. The electricity produced by the system goes to the central supply of the building: if there is a demand, the electricity is directly consumed, for example by the heat pump which produce hot water; otherwise it goes back into the grid. In this case, a meter measure the quantity released. Another meter measure all the energy produced by the PV system and on this base it is calculated the feed in tariff which is than credited to the cooperative which own the system. 28

29 Information on the structural physics planning, if applicable - Information on the structural analysis planning, if applicable - Experiences (user opinion, actual consumption values) The assignment of the dwellings to the tenant families started in April 2012 and was. At the end of summer 2012, only one dwelling was still vacant, but has been assigned at the end of December After the assignment of the dwelling, each family has been briefed about the correct use of the technical services and of the building. In order to test the degree of satisfaction of the tenants and to verify the correct use of the technical services, during the second week of January 2013 a survey has been conducted on 16 of the 18 families (1 dwelling was just assigned and another is rented by a family who was unable to reply due to linguistic barriers, both in the certified block). 6 questions with multiple choices were made about the usage during the winter period, 7 questions for the summer period. The answers have been used to provide further feedback to the tenants. Some of the more interesting results for this study are: - 15/16 say that indoor temperature in summer is always good while 1/16 says that it is often too high - 14/16 say that indoor temperature in winter is always good while 1/16 says that it sometimes is not enough and another one says that often is not enough because the sleeping room is too cold. - During the winter period, 3/16 say that they keep the ventilation systems off, and another 6/16 say that they ventilate both using the ventilation system and opening regularly the windows - During the summer period, 5/16 say that they keep the ventilation systems off 29

30 - 7/16 say that during winter the heat pump is off most of the days - 11/16 say that during winter, the electrical radiator in the bathroom is kept off or is on but generally cold (because the set temperature of the thermostat is already verified) - Only 3/16 say that during summer they use the cooling system, 2 of which live in one of the 6 smaller dwellings where all the windows are facing the same direction. - 9/16 use the shading curtains often, only 4 never (2 of which because the tends have some part broken) From April 2012, it has started a program to monitor energy consumption in the 2 blocks. For this purpose, a web based database is currently been used. This is a web application which allow for monitoring consumption data in the building and gives open access to a summary of consumption for the entire building. Monitoring is based on 2 readings per year of the meters which are installed in the building. Readings are made on 15 th of April and 15 th of October, in order to divide summer consumption from winter consumption. The energy meters which are monitored in the building are: Electricity (central supply) kwh Electricity (PV system) kwh Electricity (1 per flat) kwh Electricity (1 per flat) kwh Lighting of common spaces, lift, centralized (heat pump) hot water system including circulation pump (minus) electricity produced by the PV system which is not immediately used (and hence is released into the grid) Total electricity produced by the PV system All the consumption in the flat including cooking (induction plates), lighting, white appliances, heating and cooling (heat pump), mechanical ventilation A divisional meter under the previous one which allow to separate the consumption for heating (heat pump plus the electrical radiator), cooling and ventilation For the period 15/4 15/ , the only significant values where those of the total production of the PV system, since the apartments were only partly occupied. The system (20 kwp) has produced a total of kwh in this period (726 kwh/kwp), corresponding to 26 kwh/m 2 (the heated net area of one block is 560 m 2 ). The first winter values will be available after 15 th of April 2013, but estimation based on an intermediate reading done on the 16/1/2013 give us the following values for the entire year: Usage electricity (kwh/m 2.a) primary energy (kwh/m 2.a) Heating and ventilation Other electricity consumption inside the dwelling Typically: induction cooking stove, refrigeration, washing machines, lighting, hi-fi and computers... 30

31 Hot water and building services 2 Consumption (total) Production (photovoltaic) Consumption - production It is important to note that all energy consumptions are included in the table above, nothing is left out. If we compare with the table of PHPP predicted consumption (page 24), we note that consumption is a bit higher, specially for what concern auxiliary electricity and hot water production from one side and household appliances on the other. In total, about 22% higher, which is not a bad result considering that is the first year of usage. If we consider only the comfort energy (heating, ventilation, hot water and building services), the balance of the building is positive being the energy produced by the PV system 67% more than the energy consumed. So referring to the EU Directive 31/2010, we could say that this is a positive building or active building. Of course these are only estimates extrapolated on partial data (first half of the heating period between 2012 and 2013). A complete record for the winter period will be available after the 15 th of April 2013 and for the complete year after 15 th October Monitoring results will be publically accessible at this web page project ID Lonato Casa Light. 2 Building services includes the lift, the lighting of the common areas, all auxiliary energy of the DHW system and all the other centralized systems) 31

32 References to existing studies/ publications on this project The project has been published on the Regione Lombardia low energy building collection LombArdia +, on the IPA magazine La Passive House, on the BEMA magazine Progetto energia n. 61/2010. The project is used as case study of low energy buildings in the Power House Database: The project consumption data are accessible on the following on-line database: 32