Installing better insulation and preventing air leakage are two of the most important steps that homeowners can take to reduce energy bills and improve comfort levels. With fuel costs going through the roof, what are the practical steps homeowners can take to bear down on energy consumption?
Here we take a look at how the owners of an attractive, traditionally built home in Stockbridge, Hampshire tackled the issue of escalating running costs.
Originally built in the late 1980’s the house had been extended in the year 2000 to provide first floor bedrooms over the existing attached garage. The modern, very comfortable looking property has oil fired central heating but fuel consumption was felt to be high.
In 2020 the owners engaged Abingdon based energy efficiency consultants, Sustainable Lifestyles Ltd to undertake a thermal imaging survey to assess the property and suggest options for improvement.
Their survey highlighted a poor standard of insulation and air tightness and recommended a programme of remedial action to improve the thermal performance of the house.
Poor performance of UK housing stock
On a wider perspective, the property is typical of many of homes in the UK. The Government estimates that roughly 12 million of the 29 million homes in the country fall below C grade on the Energy Performance Certification scale which is graded from A-G. The closer to A, the more efficient the home meaning it should have lower energy consumption and a smaller carbon footprint. Grade G is at the other end of the scale with C being just above average.
With around 20% of UK carbon emissions generated through domestic heating, hot water and cooking, the scale of the problem is clearly enormous.
A “Fabric First” approach to improving the efficiency of walls and lofts is being proposed in the UK and the Government acknowledges the importance of this methodology in its Heat and Building Strategy, published in October 2021. So far, £3.9bn has been earmarked to support low emission homes and, according to Jan Rosenow of the clean energy think tank Regulatory Assistance Project, investing in insulation is “critical” if Britain is to cut energy consumption and meet climate goals.
Better insulation and improved air tightness
According to Paul Buckingham, of Sustainable Lifestyles, going hand in hand with better standards of insulation is the need to reduce air leakage – draughts to you and me. “Up to 40% of a buildings heat loss can be attributed to air leakage,” said Paul. “So it’s vital that reducing air leakage is included in any programme of measures to improve a building’s thermal performance,” he added.
At the Stockbridge property, Sustainable Lifestyles recommended a programme of improvements to the insulation including the replacement of the existing cavity wall insulation from areas where it had sagged and become ineffective. They engaged a specialist insulation contractor, Prize Spraying from nearby Swanwick, Southampton to inject closed cell cavity wall insulation and apply open cell spray foam insulation to the roof and first floor voids.
Prize Spraying Ltd is part of Huntsman Building Solutions’ qualified network of authorised contractors. HBS manufactures a range of high-performance spray applied insulation and coating systems for many building applications including roofs, floors and walls.
Their insulation products were developed in Canada to cope with their severe winter conditions and according to Jason Prizeman of Prize Spraying, are now widely used across the UK in both commercial and residential buildings.
HBS H2Foam Lite, open-cell insulation
Prize Spraying recommended the HBS H2Foam Lite spray foam insulation which is a flexible “open cell” material with an elastic, yielding texture. Foam Lite not only provides outstanding levels of thermal insulation, but also allows the building to breath naturally, resisting internal condensation and at the same time eliminating draughts.
H2Foam Lite is installed using a pressurised gun system. Foams are applied as a two-component mixture that come together forming a foam that expands 100-fold within seconds, closing off all gaps, service holes and hard to get to spaces that conventional insulation materials fail to reach.
Unlike the urethane foams of 20 years ago, modern spray foams such as H2Foam Lite uses water as the blowing agent. This means that the reaction between the two components produces a small amount of CO2 which causes the foam to expand. Cells of the foam burst and the CO2 is replaced by air. From an environmental perspective, H2 Foam Lite has a Global Warming Potential of 1 and an Ozone Depletion Potential of 0 .
According to Huntsman Building Solutions, H2 Foam Lite E is currently the only spray foam insulation system to carry the prestigious BBA Certification.
Access to complex roof structure
Because of the complex nature of the first-floor roof and dormer structure, contractors were brought in to remove roof tiles and strip back membrane to allow access for spraying. H2Foam Lite was sprayed to a thickness of 100mm between joists and the membrane repaired and tiles replaced. Similarly, cladding to the front and rear dormers was removed to allow spraying, with cladding later replaced.
For the main front and rear gables, existing timber cladding was removed to allow disposal of the original fibre-glass insulation that had sagged and failed. These areas were sprayed externally and new cladding reinstated.
The pitched roof area above the first-floor bedrooms had good hatch-access and Prize Spraying used an extended application lance to spray insulation foam here and also to gain access into the adjacent eaves voids, behind the bedroom walls.
External brick and block cavity walls of the original building were injected with a 60mm thick layer of HBS closed-cell spray foam insulation to complete the remedial works. The year 2000 extension already contained cavity insulation bats so were not given any additional treatment.
75% improvement in thermal performance
On completion of the works a further thermal imaging survey was undertaken and photographs show clear improvement in heat retention and significant reduction in air leakage. Sustainable Lifestyles estimate a 75% improvement in thermal performance.
Internal/external, overnight temperature monitoring data collected by the homeowner over an extended period supports these conclusions. On a particularly cold winter night, external temperature fell to -5.0deg C but internal temperature fell by only 2.1deg C despite the central heating being switched off.
Data to support reduction in annual fuel oil consumption is still being collected but the thermal imaging photography and anecdotal evidence from the homeowners is compelling.
Thanks go to Prize Spraying www.prizespraying.com and Sustainable Lifestyles www.sustainablelifestyles.co.uk in the preparation of this article.
For more information on Huntsman Building Solutions visit: www.huntsmanbuildingsolutions.co.uk
For more information about HBS H2Foam Lite products: https://huntsmanbuildingsolutions.com/en-GB/products/open-cell-insulation