The ‘Sunlighthouse’ in Pressbaum near Vienna emerged as the winner of a competition which Velux had invited nine emerging Austrian architectural offices to compete in 2008. Subsequently, an intensive 18 months planning and optimisation phase began. In comparison, the actual construction phase of six months was relatively short. Timber was chosen as a building material for three reasons: it has a reasonable CO2 balance, it was the architects’ preference and it enables speedy construction. A mere three days were required to assemble the ceilings and the wall elements, including the facade cladding of the two upper floors.
Today, the economic use of energy must be a given for every building – even more so for a building that claims to be a ‘Model Home 2020’. From an energy standpoint the most important planning goal for the Sunlighthouse was therefore a positive energy balance. The energy required for the building ought, as far as possible, be minimized and sourced solely from renewable energies. This was achieved with a well insulated and airtight building envelope (U-value external wall: 0.13 W/m2K; roof: 0.12 W/m2K; triple-glazing with Ug = 0.7 W/m2K). The combination of a ventilation facility with an efficient heat recovery system means that the building's heating requirements are 24 kWh/m2a for the heated gross floor space.
In its net annual energy use, the Sunlighthouse is a CO2 neutral plus energy house with an entirely renewable energy supply. Over the course of the year, the 43m2 photovoltaic system generates more electricity than needed for all energy-based applications (including electricity for the household). Photovoltaic energy counts as the most important positive factor in the CO2 balance, i.e. in the compensation of greenhouse gas emissions.
In order to minimise electricity requirements, electric lighting was optimised through a daylight and use-dependant control system. Furthermore, the house was installed with appliances of the highest available energy class. Some appliances typically used in single family homes were omitted entirely. For example, a window that can be opened in the kitchen replaces the extractor hood. Instead of a clothes dryer, a drying cabinet connected to the ventilation system was installed in the basement.
Heating and hot water for the house are supplied by a 3.3 kW brine-to-water heat pump which is integrated into a compact heat recovery ventilation unit. The heat pump draws environmental heat from a ground collector buried in the garden and feeds the heat energy into a low temperature underfloor heating system. It is supported by a thermal solar system with a collector area of 8 m² which covers 70?% of the building’s warm water requirements throughout the year. As an additional perk, even though not strictly necessary, the heat pump can also be operated as a cooling device. As a desired side effect, the ground collector is thereby thermally regenerated and is thus better prepared for winter operation.
In terms of ventilation the client opted for a double strategy: when external temperatures drop below 14?°C the ventilation system operates in conjunction the heat recovery system. When temperatures rise above this threshold, the house is ventilated by an automatic window operation system. The opening and closing of the windows is dependant on the CO2 levels of the air in the room, in addition to internal and external air temperatures, wind speeds and rain. The most critical factor for opening the windows is a CO2 concentration of 600 ppm in the internal air.
Today, the economic use of energy must be a given for every building – even more so for a building that claims to be a ‘Model Home 2020’. From an energy standpoint the most important planning goal for the Sunlighthouse was therefore a positive energy balance. The energy required for the building ought, as far as possible, be minimized and sourced solely from renewable energies. This was achieved with a well insulated and airtight building envelope (U-value external wall: 0.13 W/m2K; roof: 0.12 W/m2K; triple-glazing with Ug = 0.7 W/m2K). The combination of a ventilation facility with an efficient heat recovery system means that the building's heating requirements are 24 kWh/m2a for the heated gross floor space.
In its net annual energy use, the Sunlighthouse is a CO2 neutral plus energy house with an entirely renewable energy supply. Over the course of the year, the 43m2 photovoltaic system generates more electricity than needed for all energy-based applications (including electricity for the household). Photovoltaic energy counts as the most important positive factor in the CO2 balance, i.e. in the compensation of greenhouse gas emissions.
In order to minimise electricity requirements, electric lighting was optimised through a daylight and use-dependant control system. Furthermore, the house was installed with appliances of the highest available energy class. Some appliances typically used in single family homes were omitted entirely. For example, a window that can be opened in the kitchen replaces the extractor hood. Instead of a clothes dryer, a drying cabinet connected to the ventilation system was installed in the basement.
Heating and hot water for the house are supplied by a 3.3 kW brine-to-water heat pump which is integrated into a compact heat recovery ventilation unit. The heat pump draws environmental heat from a ground collector buried in the garden and feeds the heat energy into a low temperature underfloor heating system. It is supported by a thermal solar system with a collector area of 8 m² which covers 70?% of the building’s warm water requirements throughout the year. As an additional perk, even though not strictly necessary, the heat pump can also be operated as a cooling device. As a desired side effect, the ground collector is thereby thermally regenerated and is thus better prepared for winter operation.
In terms of ventilation the client opted for a double strategy: when external temperatures drop below 14?°C the ventilation system operates in conjunction the heat recovery system. When temperatures rise above this threshold, the house is ventilated by an automatic window operation system. The opening and closing of the windows is dependant on the CO2 levels of the air in the room, in addition to internal and external air temperatures, wind speeds and rain. The most critical factor for opening the windows is a CO2 concentration of 600 ppm in the internal air.