As housing providers and developers, we are in a unique position when it comes to improving air quality. We must consider how we can make changes in our daily lives to improve air quality, which in turn can reduce greenhouse gas emissions and benefit people’s health.
The design, construction, operation and maintenance of buildings impacts the air we breathe, our energy consumption, and our health. Heating and cooling homes, as well as the amount of gas and electric a household needs to use all has an effect on carbon emissions and our reliance on fossil fuels. While our actions might be more indirect, less ‘immediate’ and require more planning and expertise than perhaps reducing emissions by driving less, our work has a huge impact; dictating the levels of carbon emissions produced by homes now and in the future.
Back in 2009, Radian set out on its ‘Towards Zero Carbon’ programme; developing a number of pilot housing schemes in order to evaluate methods of construction and the use of renewable energy technologies that would enable us to deliver new homes to meet the Government’s target at that time to be Zero Carbon by 2016.
We utilised different techniques before evaluating the results, including SIPS panels, timber frame and masonry construction and adopted a range of renewable technologies which included heat pumps, Biomass, PV, Solar hot water and rainwater harvesting installations alongside electricity, gas and communal heating systems.
Our post occupancy evaluation focussed on ease and cost of construction and maintenance but specifically on what worked well for our residents to ensure ease of operation and affordability. We found that what worked best for our residents and ourselves, as developers, was a ‘fabric first’ approach with efficient heating and hot water systems supplemented using PV where needed. The outcome seems obvious now but in the early years of this century, the focus on innovation and technology was seductive and avoiding over complex solutions was a welcome result!
A ‘fabric first’ approach to building design involves maximising the performance of the components and materials that make up the building fabric itself, before considering the use of mechanical or electrical building services systems. Benefits include:
- Maximising airtightness
- Using super-high insulation
- Optimising solar gain through the provision of openings and shading whilst reducing overheating
- Optimising natural ventilation
- Using the thermal mass of the building fabric
- Using energy from occupants, electronic devices, cookers and so on
Ten years on, Government policy on delivering sustainable homes has moved on; the Zero Carbon targets of a decade ago have shifted significantly and continue to do so and we have informed future developments in line with this.
Recently we completed our Quebec Park development at Whitehill Bordon in Hampshire where we specified a fabric first approach combined with energy efficient gas boilers and photovoltaic panels in order to meet very stringent low carbon targets required under our planning obligations. But, in the wider housing sector, it’s become increasingly clear that one of the major issues with delivering sustainable homes is the performance gap between the homes as modelled and the homes as built. A lot of work over the last few years by the Zero Carbon Hub and others has focused on this.
For the Whitehill and Bordon Regeneration, the local authority (EHDC) had engaged with the National Energy Foundation (NEF) to look at adopting its Assured Performance Process (APP) for the new developments in the town as it grows. Radian agreed to trial and embrace the APP process at its Quebec Park development because we are keen to ensure the quality of our built stock and the performance of our homes which need to perform the way they were designed to do. At its heart the APP is about focussing on all aspects of the process through design detailing and construction to ensure that the development performs in line with the design intentions. The APP involved early review of the design details with the Architect and design team as well as with the specialist suppliers. They suggested improvements and provided constructive challenge during the process. Their input helped to:
- Reduce thermal bridging by moving the windows in relation to the insulation layer, reducing the ‘timber fraction’ at junctions and lintels and extending a warm roof across a terrace of several homes to cut the number of thermal bridges.
- Avoid ambiguity in design drawings by drawing thermal bridge details
- Provide certainty of performance in the details being considered
On site they worked with the contractor through regular site visits and toolbox talks to ensure the team understood the importance of getting details right and maintaining consistency of quality. Once built, thermal imagery scans of the properties clearly showed that cold bridging had largely been eliminated and insulation was installed consistently throughout the properties. Early indications from the Monitoring and Post Occupancy Evaluation of a number of the properties is illustrating that they are performing as they were designed which is a clear vindication of the process adopted.
Overall, by adopting good working practices and focusing on ensuring that the fabric performs through attention to detail and build quality, we have managed to deliver homes with similar performance to those homes where high levels of renewables and technology were relied on to deliver sustainability targets in the past. Where the build quality of volume house building continues to be an issue, it is reassuring that by adopting an Assured Performance Process we have been able to deliver a quality product that also performs as it was designed.
The Quebec Park scheme is becoming recognised in the industry for the outcomes it has produced both in its urban design form and for its performance receiving significant awards and plaudits. Although such success is great recognition, for Radian, replicating Quebec Park is the sustainability target for the future.
To deliver well designed and built homes that perform well, are easy to operate and occupy, that contribute to employment and the health and wellbeing of customers all while creating a sense of community, is surely what truly sustainable, environmentally friendly development is about. Not a bad outcome for a simple programme designed to deliver Zero Carbon by 2016!
Head of Construction
