The term Passivhaus is not an energy standard. The standard can be met using a variety of technologies, designs and materials, and is a refinement of the low-energy house standard. Neither is Passivhaus a brand name, it is a construction standard, a standard that is truly energy efficient, comfortable, affordable and ecological.
A Passivhaus is more than just a low energy building
• Passivhaus allow for energy savings of up to 90% compared with typical buildings and over 75% compared with average new constructions.
• Passive Houses are also praised for their high level of comfort. They use energy sources inside the building such as the body heat from the residents or solar heat entering the building – making heating a lot easier.
• Special triple glazed windows and a building shell consisting of highly insulated exterior walls, roof and floor slab keep the desired warmth in the house.
• A ventilation system consistently supplies fresh air making for superior air quality without causing any unpleasant draughts. A highly efficient heat recovery unit allows for the heat contained in the exhaust air to be re-used.
The vast energy savings in Passivhaus’s are achieved by using especially energy efficient building components and a quality ventilation system.
The five basic principles of Passivhaus design are:
Passiv buildings assure a healthy, comfortable indoor climate in both summer and winter without the need for a conventional heating system thus considerably reducing the buildings energy consumption as shown below.
Passivhaus standards significantly exceed current Government annual energy output proposals.
Thermal comfort is achieved to a maximum extent through passive measures (insulation, heat recovery, passive use of solar energy and internal heat sources).
The starting point for differing parameters include:
• Total Energy demand for space heating less that 15kWh/m2/yr
• Thermal bridge free construction
• An average U-value of the opaque building envelope of 0.10 W/m2K
• An average U-value of the entire window area of 0.80 W/m2K
• An entire window area of 0.4 x living area
• 70% of windows south facing
• A room temperature of 20°C
The Passivhaus approach improves on the standard low energy building design improving on, amongst others, very high levels of insulation, super-insulated opening windows, airtight building fabric, cold bridges etc. This results in properties which stay comfortable ‘passively’ for most of the year without the need for conventional heating systems.
The Passivhaus standard includes a target for unregulated energy demand. The Passivhaus standard sets a primary energy limit of 120kWh/m2/yr. In order to achieve this, the primary energy demand for all activities (including cooking and appliances) within the home must be reduced. This can be achieved through specification of energy efficient light fittings and appliances, and well designed and insulated hot water supply, plus the use of low carbon energy supply.
Integrity understands that some clients will not necessarily want or be able to achieve Passivhaus Standard but will still require the proposed Government figures to be matched or bettered. Our connection with Passivhaus enables us to work with clients to achieve the energy efficiency in their green homes sustainable buildings that they require.
To achieve the Passivhaus standard requires meticulous attention to design and detailing combined with a high quality of construction.