Ian Armstrong, Director of ARCO2 Sustainable Architecture explains…

How would you define sustainable design?

For me, the definition is to reduce or eliminate negative environmental aspects through thoughtful design; it’s about being responsible! This really starts with first principles in terms of careful analysis of the site such as location, orientation, form (factor), sun shading, excavation, choice of materials, renewable energy technologies, fixings and fittings. It’s about designing a building that uses sustainable low-embodied energy and responsibly sourced materials, but also materials that can, at the end of the building life, be re-used, decompose and dis-assembled wherever possible. It’s also important to minimise maintenance and, where possible, sourcing as local as possible to minimise travelling and carbon, which in turn helps the local economy.

What role do you believe low carbon materials and renewable energy sources will play in the future of house design?

Low carbon materials and renewable energy sources and in particular low energy sustainable buildings are the future. We need to find a solution to making concrete sustainable or an alternative that is available throughout the world. Concrete is one of the biggest construction polluters and in particular the binder cement. The production produces large amounts of CO2 (about 0.9 pounds of CO2 for every pound of cement) estimated at 8% of all global carbon emissions. Concrete is also the 2nd most consumed material globally. My feeling is that governments need to push harder and faster to ensure our current and future construction projects are as sustainable as possible. The industry is changing, but not fast enough!

Featherbeds | ARCO2

Featherbeds | ARCO2

Can you explain what ‘embodied’ carbon is?

Embodied carbon is the amount of carbon used to produce a material and ultimately a building. We often refer to the carbon footprint which includes consideration of embodied carbon to produce the building, but it’s also the amount of CO2 produced running and maintaining the building and then, eventually at the end of its life, the carbon produced in demolishing, transporting waste and recycling. We therefore need to very carefully consider the life and after-life of the building and the materials we use; we don’t want to pass the problem on to future generations to solve

Can you give some examples of low carbon materials and how they are used to reduce a building’s embodied carbon?

I would consider selecting materials that sequester carbon and have minimal reliance on CO2 during their production. Timber from sustainable sources (PEFC/FSC) is a good example. However, we also need consider how we heat our buildings, provide hot water, lighting and electric for appliances. As mentioned earlier, sourcing locally or from the UK helps to reduce CO2 through transportation, whilst also benefitting the local economy. There are many innovative recycled products now coming to the market, however we still need to consider if they can be recycled at the end of their life.

Tresidder | ARCO2

Tresidder | ARCO2

Can you give some examples of renewable energy sources used in your designs?

The majority of our projects feature photovoltaic solar panels to produce on-site electricity. We also tend to use heat pump technology for all hot water and heating demand. We have used ground source, air source and water source systems distributed via underfloor heating pipes. We have also used solar thermal collection for hot water heating and heat recovery fresh air system for ventilation.

Do you feel using low carbon material/renewable energy impacts or constrains design in any way? Or rather, inspires/innovates?

It is extremely important to carefully analyse the site and the client’s brief in order to ensure that the fundamental design decisions are in place. Location, siting and orientation are perhaps the most inspiring impacts together with form. The materials, systems specification and renewables should be considered at the outset and become integral parts to the design process. They should never be considered as bolt-ons, but key fundamentals of the building as a whole.

Do you feel that sustainable design goes beyond the bricks and mortar? For example, that it impacts on occupant comfort and wellbeing?

Absolutely, designing and building low energy architecture will provide much better comfort and promote health and wellbeing. Ethically and morally the benefit of living a sustainable lifestyle can help to improve mental wellbeing, knowing that you are doing as much as you can to minimise your impact upon the environment.

Waterhouse | ARCO2

As you specialise in sustainable design, does this change the way you work and/or your approach to work?

No, this is the way we work, there is no other way!

Can you give examples of projects that embody green design?

Waterhouse, Featherbeds, Tresidder and Wayside all embody this ethos.