Developed in 1996, five years after the first experimental PassivHaus project, the PassivHaus standard relies upon a very simple set of premises; very high levels of insulation, elimination of cold bridges, super-insulated triple glazed windows orientated to the south to maximise passive solar gain, and an incredibly well sealed building fabric. It is estimated that using the PassivHaus method to construct a typical house results in a 90% reduction of carbon emissions compared to that of an average home.
Concrete will bring major benefits to the passive eco design, in the exploitation of its thermal mass. All components of the exterior shell of a Passivhaus are insulated to achieve a U-Value that does not exceed 0.15 W/m2/K – typical house is around 0.25 to 0.35. The thermal mass of concrete helps store large amounts of heat and then release this heat back into the building footprint which in turn helps to maintain and control the internal temperature of the building without the use of traditional central heating, hence the term, ‘Passiv’.
Aggregate Industries through our Charcon Precast Solutions business are proud to be involved in the first certified Passivhaus in England which will be featured in the Grand Designs programme.
The Passivhaus is located just outside the market town of Moreton-In-Marsh in Gloucestershire and is due for completion in early 2010. The house is being built into a hillside, with has been constructed underneath a 300 year old listed stone barn. The house will eventually be hidden from the surrounding countryside by having the excavated hillside built back on top of the house.
The offsite precast concrete panels demonstrate sustainability, and innovation and form a monolithic structure which will be naturally airtight, minimising air leakage through joints compared with traditional brick and block. Air leakage through unsealed joints must be less than 0.6 times the house volume per hour (this is the equivalent of an air permeability value of less than 1 m3/hr/m2 @ 50 Pa). About 10x better than a typical new-built.
The use of precast concrete in particular will give all of the benefits of off-site construction with reduced wastage, but will also of course give a superior finish, important because much of it will be exposed internally.