To the Passive Observer

A home which saves 90% of the energy used by a conventional new house, with only 10% of the normal bills and completely new air every 2.5 hours entirely eliminating odour and vastly improving air quality. Does this sound too good to be true?

The Passivhaus dwelling is the world’s leading standard in energy efficient construction, a voluntary building standard which exceeds the present regulations by far. It results in buildings that require little or no energy use for heating or cooling and the remaining heating and hot water demand can be covered almost completely by renewable energies. Such a house is designed and built using a step-by-step approach, with efficient components and a whole house ventilation system to achieve exceptionally low running costs; and at the same time is comfortable, healthy and sustainable.

So it is hard to believe that as yet there are no passive houses in Scotland although this may not be far away. Scottish-based architect Tom Robinson has been working on low energy house design for many years and preaches about the benefits of Passive house construction, which was first developed in Germany in 1996, five years after the first experimental PassivHaus project.

He said: “I have built two houses for my family, and if I ever do it again, the next will definitely be a Passivhaus. For us Scots, the thought of living in a wonderfully warm house that barely costs a penny sounds fantastic.”

So what is a Passivhaus? Simply put, it is a house where the architect has used a known design methodology to create a low energy dwelling that meets certain standards. It will have exceptional thermal performance and where energy is consumed it is used intelligently, for instance retaining heat created from activities such as cooking, watching television and showering. The architectural form and look of the house is entirely up to the client and their architect to create. The Passiv principals are just another set of influences that will affect the design. “It doesn’t mean a house without heating, but it just doesn’t need radiators and all the associated plumbing. On the coldest days of the year effective heating is easily achieved with a small heater in the ventilation system. Considering space heating and hot water accounts for around 60% of the energy we use, these energy saving measures have a significant impact on reducing the impact on our environment, and could also go someway to eliminating fuel poverty.”

Whilst the design is already popular in The Czech Republic, Germany and Austria, Tom Robinson is keen to find a client with which to create a Passivhaus for Scotland. He said: “The climate is right just now. Energy prices are likely to keep rising in the long-term, land values are down and builders are keener and more competitive. It has been said before that often the best buildings are built during recessions and perhaps these are the times when everyone thinks about things that bit harder.”

Not only do the Passiv principals promote energy efficiency but good health too. One of the UK’s key health concerns is inevitably the rising levels of asthma in children. The Passiv ventilation system helps to ensure permanent fresh air, with out uncomfortable drafts and whilst regulating humidity; this reducing the levels of dust mites and also prevents the growth of moulds. So, in turn this means healthier, happier children, and parents too.

In the past sustainable/ecological architecture has often appeared a little odd. Features such as trombe walls, solar collector spaces, grass roofs and turbines, can almost completely dominate the external aesthetic of a building. Their proponents are often happy about this and keen to celebrate them, but actually these things can have serious downsides, which the less environmentally committed clients will not be so happy with and perhaps that is one reason why such buildings remain less popular.

Every architect has different opinions on the importance of the various influences that affect ‘the design’ of a building, and it’s these views that offer variety. In North Africa modest family dwellings are constructed from adobe (earth blocks) to provide basic shelters - the variety is there, but in a very controlled way. However, in the West, technically most things can be considered but some restraint is required because the choices are so vast. Tom said: “If you think what you are contemplating might be fashion, then don’t do it. In the current climate the prevalence for expensive fashion or ‘building bling’ in architecture is subsiding and people are looking for deeper qualities instead. In building today there is a desire to do something good from an environmental standpoint but also from a cultural perspective, and to ensure the long term solution is viable.”

The key features of a Passivhaus include interiors flooded with light, as orientation and the balance of glazed interiors are key, with high quality windows and doors with greater longevity and lower maintenance. Compliance with the PassivHaus standard must be assessed using the PassivHaus Planning Package but the following will be taken in to consideration:

• Compact form and good insulation
• Southern orientation and shade considerations
• Energy-efficient window glazing and frames
• Building envelope air-tightness
• Passive preheating of fresh air
• Highly efficient heat recovery from exhaust air using an air-to-air heat exchanger
• Energy-saving household appliances

• Total energy demand for space heating and cooling

The three architectural tenets of Vitruvius, the Roman architect and engineer, (commodity, firmness and delight) remain all important in Tom’s work, as does respect for context and use of local materials whenever possible. He said: “Buildings should lift the spirit and be a joy to inhabit. These things remain the real governing architectural drivers but with an understanding of the technical aspects and what can be learned from Dr. Feist, the inventor of Passivhaus design methodology, much can be achieved in making sustainable, environmentally conscious architecture also beautiful.”