Eco Design

Self-Building Towards an Environment-Friendly Future

Whether you are looking to reduce your energy costs; create a healthier, more comfortable space to live; or simply want to act more responsibly towards our environment, choosing to build more ecologically is one of the most effective steps you can make.


An eco home is one that embraces energy-saving construction techniques, avoids the use of environmentally damaging building materials and seeks to create buildings that are simple and efficient to understand and operate yet economic to build.

With the right design skills, passion and attention to detail, it is possible to build homes that can be:

    • heated almost entirely through occupation and the warmth of the sun alone (yes, even here in the UK);
    • equipped to harness that same solar power to generate hot water or electricity;
    • crafted from components and technologies that don’t cost, or damage, the earth;
    • fashioned to deliver indoor spaces that are healthier to live in, regardless of the environment found beyond the doorstep.

Eco building also means favouring the use of green materials such as timber, natural insulations or clay products over the specification of concrete or petro-chemical-derived foams and plastics since far less energy is used, or carbon dioxide emitted, in their manufacture – some plant-based materials even lock in carbon. We have valuable experience in selecting and designing with such products and will be able to suggest the most appropriate eco specification for your building.


By far the biggest environmental impact of any home is the heat energy used over its lifetime. In the order of 62% of all household energy use is for space heating, with a further 18% for hot water generation plus 3% on lighting, 3% on cooking appliances and the remaining 14% on general electrical appliances. Clearly, cutting down on heat energy use should be the overriding consideration in the design of eco-friendly buildings and we seek to design buildings that perform well above basic Building Regulations. With greater consideration given to compact building forms, higher insulation levels and orientation that takes advantage of free solar energy, our low energy designs can reduce fuel bills significantly.

We can improve even further on this, however, through Passivhaus design techniques and technologies to deliver homes that use up to 80% less heating energy, with high internal air quality free of pollutants or dust and internal temperatures that never drop below comfortable with only the minimum of heat input. Passivhaus homes are quieter, healthier and more sustainable than any other dwellings – so much so that many European cities now insist on Passivhaus standards for all new buildings. Buildings that are independently certified as having achieved the Passivhaus standard are ensured to provide internal comfort standards that are of the highest standard in terms of warmth and air quality, for the absolute minimum expenditure of energy and fuel costs – who wouldn’t want to live in a place with those credentials? Passivhaus also puts the ‘net zero carbon’ home within easy reach of house holders, for example, through a roof-mounted photovoltaic array.


The target for all Passivhaus buildings is to reach a level of efficiency whereby the space heating demand is reduced to just 10 watts per square metre (10W/m2). To put this into context, this means that an entire three-bedroom house of 150m2 requires a total peak heat input of 1500W, even when external temperatures are below freezing – equivalent to one small portable fan heater. Over the course of a year, the corrected target is 15 kilowatt hours per square metre per year (15 kWh/m2/yr – 1 kWh is equivalent to one unit of gas or electricity from your bill). So, in the case of our 150m2 house, this gives an annual space heating demand of just 2250 kWh, or a cost of around £10 per month (if using a condensing gas boiler). Truly affordable warmth like this provides major benefits in terms of health.


All Passivhaus projects have to be verified by an official iPHA Passivhaus Certifier, of which there are a small number based in the UK. We form a collaborative working relationship with the Certifier early in the project so that there are no late-stage design compliance issues. Similarly, working with the Contractor as early as possible can bring dividends later when the project starts on site. Cowan Architects has an established track record in the successful delivery of projects through the construction phase. For your Passivhaus project, a good relationship with the construction team is crucial so that they understand all the requirements of the standard in terms of workmanship quality and the provision of evidence. Cowan Architects prefer to have a close involvement throughout the build to give guidance and check compliance with the design proposals on the client’s behalf.

We also regularly work with traditional properties and, with 1.2 million homes lying within conservation areas, we recognise the need to preserve our built heritage whilst giving all households a fair opportunity to reduce their energy needs and costs.

Scroll through our Eco-Home Portfolio