Climate change and sustainable building

— 16 Jun 2021

One of the key topics to be discussed at the G7 summit in Cornwall was climate change and energy policy.

Coming hot on the heels of the first in our series of blogs on sustainability in architecture it seemed like an opportune moment to share the Energy Performance Certificate (EPC) results of a recently completed new build property on the North Devon coast.

Designed for an artist, the property is a bespoke residence in an Area of Outstanding Natural Beauty and replaced an outdated bungalow on a stunning coastal site.

Working with the client’s brief, constraints and opportunities of the site, sustainability factors are:

Orientation

• Room positions and large amounts of glazing maximise the stunning coastal views but also solar gains.
• The extended eaves of a verandah on two sides, shade the interior from the high summer sun keeping the house cool.

Insulation

• High quantity and specification of insulation in the walls, floors, and roofs of the dwelling to retain heat generated.
• High air tightness of the building envelope to minimize heat loss through air leakage. Current Building Regulations requirements for air permeability of less than 10m³/h/m² – this dwelling achieves 3.6m³/h/m²

Renewable energy

• Solar PV panels – 4.8kW in-roof panels, predicted to provide approximately 4,819kWH’s of electricity per year.
• Air source heat pump – 8.5kW unit for hot water and underfloor heating.

Water efficiency

• The requirement for all new dwellings is to use a maximum of 125 litres of water per person per day.
• A 3000L rainwater harvesting system installed contributes approximately 35 litres/person/day for flushing toilets, washing clothes and external taps.
• Harvesting plus water efficient fittings and appliances means the house uses approximately 83 ltr/person/day – well below the maximum.

The house is not built to Passivhaus standards, and yet with careful design incorporating renewable energy sources, the home has achieved an EPC rating of 94 which puts it into band A (of A-G) the highest Standard Assessment Procedure (SAP) rating band. 

To put this into context, the average property in England & Wales has a rating of 60 / band D, and the environmental impact is that the average household produces 6 tonnes of CO² from heating, lighting, power etc. per annum.

This new build property produces 0.4 tonnes of CO², which if solar water heating were to be installed could be improved to 0.0 tonnes, taking the EPC rating to 97/A.

The property far exceeds the building regulations requirements, and the client has a house that is not only environmentally responsible but also cheaper to run.

Reference figures obtained from gov.uk websites