Sustainable architecture that follows passive house principles can be broken into five main areas: thermal bridge-free design, superior windows, ventilation with heat recovery (MVHR), quality insulation and airtight construction. A passive house should be draught free, have minimal heat loss and require minimal heating not exceeding 15kWh per sq m. It should also cost less to run than a conventional house benefitting both the home owner and the environment.

However, there are other factors that lessen a building’s footprint and make it more eco-friendly. By continually innovating and investigating the latest science, ARCO2 are helping to mitigate man’s impact upon the environment. Here are some examples of how they are achieving this.

Sustainable architecture

Living roofs

ARCO2 have over twenty years’ experience in designing and building ‘green’ and ‘brown’ roofs. A ‘green’ roof is a low-maintenance vegetated roof system that stores rainwater in a lightweight engineered soil medium, where the water is taken up by plants and transpired into the air. As a result, much less water runs off the roof, as compared to conventional rooftops. They also provide an extra layer of insulation that reduces heating and cooling costs, and they are likely to last much longer than conventional roofs, since the roofing material itself is shielded from ultraviolet light and thermal stress. The vegetation on ‘green’ roofs also improves air quality, enhances the appearance of the building, and reduces the urban ‘heat island’ effect.

‘Brown’ roofs are essentially substrate based green roofs but aimed at reinstating the ecology that was present prior to development. Within built up areas that ecology is often only present on brownfield sites. The general philosophy is that components should be selected and included that will create ‘ground’ conditions on the roof that are as close as possible to those of the undeveloped site.

Sustainable materials

We have always advocated the use of natural, breathable sustainable materials including sustainably sourced sheep’s wool, straw bales, recycled newspaper insulation and timber in our buildings. We choose such materials based upon their carbon footprint, bio-degradability and overall environmental credentials. We also have a triaged selection process whereby we scout for locally sourced materials first, then the UK and then Europe. It’s about selecting the most appropriate materials and construction methods for a particular site based upon its location.

Living roof by ARCO2


As with most things there is always a balancing act to be performed. Or is there? The prevailing thought at one time was that what was considered a beautiful building wasn’t going to be the most eco-friendly. Conversely it was believed that a completely sustainable property would conflict with our concept of beauty. However, this is changing – today’s wind turbines will be tomorrow’s windmills.

For us, aesthetics and sustainability go hand in hand. Selecting appropriate materials & methods, all with environmental considerations in mind, blend harmoniously with our designs, with many working in symbiosis with the landscape. By using vernacular materials in a modern way, we like to root our buildings into the local Cornish landscape.


Lifestyle is everything in our buildings, it’s about how people want to live rather than how they currently live. We are fortunate that we don’t need to convince our clients about sustainability, they are already fully behind the concept and this is one of the main reasons they come to ARCO2.

A sustainable roof with sedum matting

Sympathetic construction

Cornwall is a region known for its natural coastal beauty. With both directors hailing from the county we strive to compliment, enhance and respect this. We want our buildings to be integral to the landscape.

Design is of course subjective but it is ultimately driven by necessity. It is dynamic and reactive and cannot live in a vacuum. This may not sit easily with some. Not everyone likes change. Many like to live in the past, others moving to Cornwall want it to remain as it is – a perceived rural idyl, but external realities have to be taken on-board and incorporated in how we build for tomorrow. Consequently, we have always innovated and firmly believe that our architecture should be of our time, utilising the latest technology and innovations.

We advocate and incorporate super insulation, air tightness, thermal bridge free construction, MVHR triple glazing, water source heat pumps, photovoltaics with battery backup, smart technology, LED technology along with automation. Where possible we specify natural paints & finishes and the utilisation of natural materials such as insulating lime plaster. Building methods carried out by our sister construction firm include twin skin timber frame work, extra wide cavity construction, ICF and external insulation.

A living roof by ARCO2

Working towards net-zero

The industry is still a long way off from achieving this, with tools to calculate not readily available to all industry professionals. Policy makers and councils need to push this further without stifling innovation. As a practice we undertake embodied carbon and operational carbon calculations for every project to ensure we learn from each project but also to lift our environmental conscience and responsibility.

Some common misconceptions

It is a common misconception that solar shading isn’t needed in the UK. Solar shading, is a form of solar control that can be used to optimise the amount of solar heat gain and visible light that is admitted into a building. Even a small amount of solar gain can add heat to a low energy property.

Is triple glazing required? Yes! An old rubble stone wall has a U-value of 2.0, double glazing comes in at 1.6 and triple at just under 1.0 (twice as good as an uninsulated stone wall but still 5 x worse than a super insulated wall).

sustainable feature, living roof by ARCO2


If you’re contemplating starting a new-build yourself, and wish to embrace a sustainable approach, but don’t know where to start, then ARCO2 could be your first port of call, get in touch with our team for your next project!