the AI PassiveHaus

The first certified passivehaus in England is nearing completion. Although it is nothing new by European standards, Seymour-Smith Architects hope that this project will mark a new era in design in the UK and hope to establish this environmentally friendly architecture technique in Britain.

Images © Seymour-Smith Architects

Follow the progress…

What is Passivhaus design?

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 also has a mechanical ventilation system to provide excellent air quality and highly efficient heat recovery.

As a result of these relatively simple concepts, the building retains heat from passive solar gain, activities such as cooking, watching television and showering, and uses it to cut the need for a central heating system.

It is estimated that using the Passivhaus method to build a typical house results in an 90% reduction of carbon emissions compared to that of an average home. By adding renewables, ours will be carbon neutral.

There are over 15,000 completed Passivhaus projects on the continent. This will be the first to have been certified in England (certified by the Scottish Passive House Centre in January 2010, on behalf of the Passivhaus Institute). The Uk trailing behind a bit, but catching on…

Images © Seymour-Smith Architects

It’s important to note that Passivhaus does not dictate the design or external appearance of the house. It is simply a method of calculating the amount of insulation, glazing, thermal mass etc. to make the best use of passive solar gain, and ensure that the resulting internal climate will always be comfortable.

A database for PassivHaus projects in Austria can be found on the website of the IG Passivhaus Österreich.

Basic Principles

A dwelling which achieves the PassivHaus standard typically includes:

• very good levels of insulation with minimal thermal bridges
• well thought out use of solar and internal gains
• excellent level of air tightness
• good indoor air quality, provided by a whole house mechanical ventilation system with highly efficient heat recovery

By specifying these features the design heat load is limited to the load that can be transported by the minimum required ventilation air.  Thus, a PassivHaus does not need a traditional heating system or active cooling to be comfortable to live in – the small heating demand can be typically met using a compact services unit which integrates heating, hot water and ventilation in one unit (although there are a variety of alternative solutions).

For Europe (40^o – 60^o Northern latitudes), a dwelling is deemed to satisfy the PassivHaus criteria if:

• the total energy demand for space heating and cooling is less than 15 kWh/m²/yr treated floor area;
• the total primary energy use for all appliances, domestic hot water and space heating and cooling is less than 120 kWh/m²/yr

These figures are verified at the design stage using the PassivHaus Planning Package.

It is also essential to follow a quality control procedure to avoid on site problems which may prevent excellent levels of air tightness and thermal insulation being achieved.

What do you think of the Passivhaus design principles?

Other relevant articles that might be of interest you...