Pushing the Energy Efficient Envelope

According to the Carbon Trust 75 per cent of a building’s heat is lost through its fabric leading to significant monetary losses for householders and an alarming environmental cost. As a result the industry is continually searching for modern methods of residential construction to offer greater energy credentials.

Chris Duckworth, commercial director of SipBuild UK, explores how the drive for sustainable construction is taking the industry huge strides closer to a more energy efficient building envelope.

At the end of the first half of 2014 energy giant British Gas announced a 24 per cent fall in its operating profit for residential supply. The drop wasn’t due to a reduction in prices, but instead a result of the mild weather. Despite such a significant fall, British Gas still made a very healthy £265m in profit which demonstrates that even in frugal times, energy provision to the residential market is big business.

While the argument will continue to rumble on as to whether the utility companies could do more to make energy more affordable – especially to the estimated 6m people in the UK who are in fuel poverty – the reality is each year the average household loses £250 worth of energy through the building’s fabric. Over the lifetime of a building that’s an eye watering sum of money householders are putting down the drain – or should I say out of the walls and loft, as this is where 50 per cent of energy is lost.

Because of this growing concern, considerable pressure has been placed upon the industry to make modern construction higher in energy performance and rightly so. For years traditional bricks and mortar buildings have been the darling of the industry – and the homeowner – but let’s face it this method’s energy credentials aren’t great and need to be supported by bolt on or renewable energy performance products. Therefore, surely the most logical approach would be to use a fabric first method which from the very start prevents energy leakage.

It’s only in the last ten years that structural insulated panels (SIPs) have, in my opinion, really been given the credit they deserve in terms of energy efficiency. But now they are one of the fastest growing methods of construction in the UK and beyond.

The best way to describe how SIPs work on a very basic level is to think of a jigsaw. Each piece has been designed specifically to join the next to form a strong structure. The same principle applies to SIPs, but instead of a pretty picture the homeowner can achieve a property that is both aesthetically pleasing but also energy efficient.

And it’s not just how SIPs are joined together that offers this energy-tight seal, it’s also the way in which they are manufactured. Within each panel is a dense mass of urethane insulation which is so tightly packed that it prevents air from passing through it. This method of insulation differs greatly from the standard quilt style insulation that usually fills wall cavities. Firstly, it’s integral to the structure of the building and isn’t a costly bolt-on the homeowner has to invest in. And secondly, it’s not prone to sagging or deterioration which can expose voids where energy can seep through like standard cavity insulation.

With a SIPs structure approximately 96 per cent of the walls are insulated and almost all (99 per cent) of the roof. Compare this with a traditional timber frame where as little as 88 per cent of the walls have continuous insulation and you can quickly realise the benefits – so much so that SIPs have been used for specialist projects in the Arctic Circle where heat retention is vital.

While little heating is required in SIP constructed homes, a growth area is in the installation of Mechanical Recovery Heat Ventilation systems. As the name suggests these systems recover heat from any wasted warm air found in rooms such as a bathroom and kitchen and recycle it to be used in other areas of the home. What’s more the energy harvested also powers the system itself.

While many people can appreciate the energy performance offered through SIP construction there is always the issue of the home’s aesthetics. Most people do prefer the look of a bricks and mortar building and they don’t have to compromise on this when using SIPs. A SIP building can be clad with any type of material including render, brick slip, timber, stone or wall tile.

When people consider designing and building a sustainable home they usually discuss energy saving products such as solar panels or wind energy harvesting. Very few look at the fabric of its construction – the area where they could make the biggest impact to both the environment and their pocket. However, growth in the SIPs market looks to be challenging this perception, encouraging more people to take a fabric-first approach.