advice

Vivid Green offers expert advice on building to PassivHaus standard - a specific construction standard for buildings which have excellent comfort conditions in both winter and summer, using low levels of energy.

If you wish to build to PassivHaus standard or include at least some of the elements in your building then we are able to provide the following services:

• assistance with overall design concept particularly in relation to heating systems
• identification of potential suppliers of equipment and services
• identification of suppliers of innovative products to satisfy specific requirements such as the need for thinner insulation

Detached four bedroom, three storey house designed according to Passivhaus principles

low energy building

The principles of low energy building have been known for many years but it is only recently as concerns over global warming have come to the fore that interest has risen and more structures, are being built with energy as a prime concern. Our flagship garden office The Penthouse is an example of such a building.

Considerable debate has raged over the pros and cons of lightweight and heavyweight structures and the benefits of buildings having significant thermal mass. That said, it is not essential to have huge amounts of thermal mass to reduce energy demand as the proponents of the PassivHaus standard in Germany have discovered.

The key elements of this standard are:

• superinsulation to give u values for walls, ceilings/rooves and floors of 0.095-0.110 Wm2/K, typically achieved using 300mm of mineral wool insulation
• triple glazed windows with a u value less than 0.8
• airtight construction.

For anything other than small spaces, the airtightness standard means that mechanical ventilation is essential to ensure good air quality. So, if warm, stale air is to be extracted and cool, fresh air brought into the structure, it makes sense to transfer the heat from the one and transfer to the other. The final key element, therefore, is:

• mechanical ventilation with heat recovery.

Mechanical ventilation and heat recovery unit

Typically these systems are 80-90% efficient and, because of all the other measures to reduce heat loss, heating systems are reduced in scale by up to 90% to approx. 1kW for a 3 bedroom semi-detached house. Having reduced the energy demand for space heating by such a large amount, the potential for renewable sources of energy to satisfy the remaining load is now far greater and, in Germany, is typically provided by development level wind turbines or CHP units.

The premium in construction costs is 8-12% depending on the type and scale of building but, over the life of the building, energy demand will be approx 80% lower than in a conventionally insulated building.

Almost every type of building has been built or refurbished to PassivHaus standard in Germany including a ski lodge at 3000m as well as offices, apartments, schools, residential care homes, terraced, semi-detached and detached housing. There are a few examples of houses built to PassivHaus standard in the UK but we have a long way to go before we catch up with the 8000 dwellings in Germany.

For further information and advice please contact us by email at mail@vividgreen.co.uk, by phone on 01582 469076 or via the website.