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ISOPA Polyurethanes Passive House

Wyróżniony Przypadek March 2014
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The Polyurethanes Passive House is a project launched on 1 September 2011 to document the construction of a passive house from floor to ceiling. The construction was completed on 4 November 2013. Built in Brussels, near the institutions of the European Union, the Polyurethanes Passive House uses polyurethane materials wherever possible, providing a living example of the environmental and economic benefits of the most modern construction standards, the passive house standard. The project was undertaken by ISOPA with the help of Bostoen construction company.


General data:

Name: ISOPA Polyurethanes Passive House

Location: Evere (Brussels-Capital Region, Belgium)

Climate: mild humid temperate

Building type: small residential (1-2 family house)

Project type: new construction

Constructor: Bostoen NV

Total living surface: 235 m² (four floors)


Building envelope:

Ground floor
Overall, building the ground floor of the Polyurethanes Passive House is very similar to that of a traditional house. The main difference is the application of two layers of polyurethane insulation board (λ=0,023 W/(mK)) (Figure 1). The insulation is comprised by 180 mm of polyurethane between the concrete slab and the screed, with a total thermal transmittance U=0,124 W/(m²K). An underfloor radiant system is embedded in the screed. Polyurethane boards provide an even thickness of insulation, higher insulating performances and allows for the direct application of floor radiant system and floor finishing. The very low thermal conductivity of polyurethane boards and optimal air tightness allow minimum heat loss.

First and upper floors
Due to radiant floor heating, each floor has to be insulated. On the first and second floor, polyurethane spray foam (λ=0,027 W/(mK)) (Figure 2) was applied on the concrete slab before placing the underfloor pipes and the floor finishing. As for the third floor, a special mortar made of 90% recycled polyurethane granulates (λ=0,046 W/(mK)) was applied.

External walls
The external walls are made of bricks. The cavity between the external wall and the supporting wall was filled with a layer of 180 mm thickness of polyurethane boards (Figure 3). In total, walls are 450 mm thick, including a remaining 20-30 mm cavity between the polyurethane board and the external wall (Figure 4). U=0,118 W/(m²K). A video detailing the installation of polyurethane panels can be watched here.

Partition walls
To guarantee optimal acoustic separation between the Polyurethane Passive House tenants and their neighbors, the 40 mm cavity between the two houses was filled with open cell polyurethane boards.

Pitched roof
The wooden roof was prefabricated and includes polyurethane boards of a total thickness of 400 mm (U=0,073 W/(m²K)) (Figure 5). Block foam panels was inserted between the rafters, integrating insulation directly into the roof structure allowing for better air tightness. A video of the installation of the roof can be watched here.

Flat roof
On the balcony above the room on the first floor, flat roof insulation is required to avoid heat loss. 240 mm polyurethane boards (λ=0,023 W/(mK)) was installed on top of the balcony slab (U=0,093 W/(m2K)).

Triple glazing (Ug=0,5 W/(m²K); g=50%) and highly insulating PVC frame with polyurethane core windows are used in the passive house (Figure 6). The key here is quality glazing and polyurethane in the window frames for excellent insulation; this allows tenants to avoid heat loss and make the most of the heating potential from sunlight.

Energy efficient technologies:
Ventilation system with heat recovery.
Modular bus-system for controlling building equipment.

Ground source heat pump (10 kW) for heating and domestic hot water (for the 5 bathrooms in the house). A floor radiant system is used for heating and geothermal free cooling.
Photovoltaic panels: 15 panels of 250 W of peak power each, for an estimated energy production of 3188 kWh/year.
Thermal panels: 2 panels for the production of hot water.

Energy values:
Energy need for heating: lower than 15 kWh/(m²year).
The thermal power peak load for heating is 2561 W; due to the use of a heat pump, the systems can reach a value of electrical peak power lower by a factor of 4, which is the considered heat pump COP. The 640 W peak load can be easily compensated with photovoltaic panels, with only a minimum of sun exposure.
Domestic hot water: fully covered by renewables thanks to solar thermal system and high efficiency ground source heat pump combined to photovoltaic systems.
Air tightness: below 0,6 air changes per hour, tested at pressure difference of 50 Pa.

Over the year, the combination of high thermal insulated and high quality envelope, the ground source heat pump, the thermal and the photovoltaic solar panels makes this building a “zero-energy” building according to Passive House standards. All energy demand for heating and hot water (and more) are produced on site.

Awards won:
Passive House Certification (pending).

During the construction of the house, some on-site visits were held (on 19 March 2012 and 18 June 2012) to show the role of polyurethane insulation in reducing the energy consumption of houses.

On 11 December 2013, ISOPA hosted the grand opening of its Polyurethane Passive House.


Lessons learnt

The Polyurethanes Passive House project was undertaken by ISOPA to demonstrate the advantages of PU insulation in very low energy buildings.

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