CPD: Exploring the means to keep out the cold

CPD test paper

Solid wall insulation

The CIOB requires members to assess and fulfil their own CPD needs. Members can therefore choose to study the CPD articles published in CM as a valid part of their personal record of CPD activity.

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Click here to be taken to the online CPD questionnaire for the February 2011 edition.

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Continuing Professional Development 

Solid wall insulation: February 2011

•  Tackling the thermal efficiency of 7 million solid wall construction homes

•  The principles of internal and external solid wall insulation

•  How they can be installed

To complete the February 2011 CPD questionnaire, scroll to the end of this article, where you will find a link to the online questionnaire. Select your answers, fill in your contact details then click “submit”. To jump to the test paper now, click here.

Insulation can help keep in the warmth in any environment

Cutting carbon emissions from existing homes is a huge challenge. Duncan Murray of the NIA explains how solid wall insulation can help

With homes producing more than a quarter of the UK’s carbon emissions, the onus on reducing their carbon footprint has never been greater — for both householders and government regulators.

The way a building is constructed, insulated, ventilated and the type of fuel used all contribute to its carbon emissions. But it’s a worrying fact that, for more than half of all homes in the UK, a significant proportion of the money spent on energy is literally lost to the atmosphere as a result of inadequate levels of insulation. According to the Energy Saving Trust, around 50% of the heat in an uninsulated home is lost through the roof and walls.

The National Insulation Association (NIA) is a not-for-profit organisation that represents more than 90% of the home insulation industry in the UK. As a membership organisation, it actively supports the government’s accelerated programme for insulating the nation’s housing stock. Its intention is to raise awareness not only of the amount of CO₂ lost through inadequate insulation, but also the amount of money that householders can save by having their homes properly insulated.

Solid wall insulation

The UK’s housing stock is estimated at approximately 24.5 million dwellings and 36% are of non-cavity wall construction, including homes built from solid brick, solid stone, pre-1944 timber frame and non-traditional materials such as concrete. These types of buildings lose more heat and energy than any other type — a worrying fact when it is estimated that around 7 million properties with solid walls have little or no insulation.

While many local authorities, housing associations, private landlords and home owners have been concentrating on filling cavities to achieve carbon savings, improving the thermal efficiency of solid-wall properties has largely been ignored. This is primarily because the solutions are deemed to be more expensive and cause greater disruption, hence why these types of dwellings are referred to as “hard to treat homes”. This is not actually correct: they are not hard to treat, just more expensive to insulate compared to cavity wall insulation and loft insulation. However, the subsequent energy savings are significantly higher.

Improving the thermal efficiency of solid wall properties is therefore an area which has massive potential for the future, particularly as little work has been carried out to date. Around 25,000 properties a year currently receive solid wall insulation (SWI) and the government’s new Green Deal, proposed under the Energy Bill with details due by autumn this year, will focus on whole house eco-makeovers. However, SWI will have to increase dramatically if the government is to hit its target of thermally upgrading approximately 6 million homes by 2020. It has been calculated that 200,000 solid-wall properties a year would have to be completed to meet this target.

Solid walls can be insulated with either external wall insulation (EWI) or internal wall insulation (IWI) and either option will greatly increase comfort, while also reducing energy bills and the associated environmental impact.

EWI and IWI can cut heating costs by up to 40% and significantly reduce the amount of CO₂ a home produces. Table 1 (below) outlines the Energy Saving Trust’s evaluation of typical cost and CO₂ savings for a gas-heated, semi-detached, three-bedroom home.

Internal wall insulation

IWI typically consists of either dry lining in the form of flexible thermal linings (commonly known as thermal wallpaper), laminated insulating plasterboard (known as thermal board) or a built-up system using fibrous insulation such as mineral wool held in place using a studwork frame.

Flexible thermal linings come on a roll and are applied like wallpaper and, with some at only 10mm thick, will not cause significant disruption during installation.

These products can be applied to ceilings as well as walls and provide a solution for properties without a loft space as well as those with solid walls. It can also be applied to the underside of floorboards. It can be easily cut to size and once the product is applied it can be painted, papered or even tiled. These products are only applied to the exterior facing interior walls of the property.

Another solution is laminated insulated plasterboard, which normally replaces existing lath and plaster and is fixed directly to the existing brick. Depending on the system, thermal boards can either be screwed or glued directly onto the brickwork just like standard plasterboard. It can be installed room by room with the occupiers in-situ. It increases a wall’s internal surface temperature within a room and also improves the room’s response to heating when heating is used intermittently. It has the lowest thermal conductivity available and allows installation on damp surfaces without drying periods because it is hydrophobic.

Taking it to the exterior 

Exterior wall insulation comprises an insulation layer fixed to the existing wall, with a protective render or decorative finish. Dry cladding offers a range of finishes such as timber panels, stone or clay tiles, brick slips (brick effect finish) or aluminium panels. EWI increases the thermal performance of the building, which is particularly relevant when refurbishing non-traditional housing. It also overcomes moisture and condensation issues, protects the existing building envelope, and can reduce heating bills by up to 25% — as well as greatly improving the appearance of the building.

EWI is a tried and tested method of upgrading the thermal performance and external appearance of existing properties which can be transformed into warm, energy efficient and attractive buildings. Improving the external appearance is particularly significant to many local authorities targeting housing projects in poorer regeneration areas. Adding EWI on a whole street basis can often raise kerb appeal and residents’ pride in their community.

Benefits of EWI include the fact that no internal living space is lost. There is minimum disruption for the residents as the work can be carried out while they are at home and there is no risk of condensation occurring within the property as it is moved to the outside of the system that is being put in place. In addition, maintenance is minimal.

Insulating from unpleasant shocks

As with any type of insulation, it’s important to use a reputable and suitably qualified installer.

All members of the NIA abide by a strict code of professional practice, which means they will work to the best possible technical and professional standards.

The code regulates a member company’s marketing approach and the contract between the customer and the installer. It also oversees how the company trains its staff, relevant health and safety procedures, customer care, guarantees, and what happens should things go wrong. Using an NIA member provides peace of mind and the assurance that work will be carried out to a specified standard.

With many local authorities and housing associations embarking on refurbishment projects in line with government targets, solid wall insulation will no doubt be high on the list of priorities. The NIA is able to offer support to client organisations by contacting its members on their behalf requesting expressions of interest to tender for work. 

Insulation panels being installed on the exterior of a typical terraced property

Internal wall insulation is all in a day’s work

Lasers and computer-controlled cutting techniques are allowing one company to retrofit internal wall insulation in a day

A social housing contractor has married laser technology, computer-controlled cutting machines and insulation in a pioneering approach to low-carbon retrofitting, writes Michael Willoughby.

United House worked with partners to insulate the inside of a Camden-council owned, three-storey Victorian house in Bertram Street, north London, with the new process, known as whole house in-situ carbon energy reduction solution, or WHISCERS. The process was developed with the help of a £150,000 grant secured under the Technology Strategy Board’s Retrofit for the Future competition.

United House hopes to roll out the system to radically cut the time and cost of insulating its share of the solid-wall housing stock in London and the south-east. Alistair Sivill, eco-refurbishment manager, is targeting a productivity rate of insulating an entire house a day, with residents remaining inside throughout. The Energy Saving Trust says occupants could benefit from fuel cost savings of nearly £600 a year and carbon emission reductions of up to 77%.

WHISCERS is a three-stage patent-pending process which starts with fitters measuring the interior rooms with laser equipment. The fitters take approximately 30 measurements per room, with each measurement taking about five minutes.

The measurements are then sent wirelessly by smartphone to the firm’s factory, where a computer-controlled cutter slices the insulation board and calculates the most efficient cuts based on the shapes of the different rooms. This takes about 10 minutes per room. The boards are marked with their intended address, wall position and orientation before being delivered and fitted. Sivill’s plan is for the fitting to be done in the afternoon following a morning’s measurement and cutting.

One of the major problems for United House and its partners — the Sustainable Energy Academy (SEA), Parity Projects and Camden Council — was finding the correct equipment.

For example, a £60,000 laser cloud system could measure a whole room at once, but created so much data that it was almost impossible to send to the factory over a smart phone. 

The system, though computer controlled, still needs constant monitoring from operatives. For example, inconsistencies with the convexity or concavity of the walls can result in ill-fitting insulation sheets. Indeed, the whole system is so new that Sivill and his colleagues have developed more than 40 standard details for common issues such as coving and preventing cold-bridging.

It’s early days for WHISCERS but United House is now midway through a project for Islington Council — Issy-Clad — to retrofit 100 homes, some traditionally and some using the new system. Once this is complete, the company will have a better idea of the system’s performance.

Sivill says the cost of the fitted internal wall insulation for the three-bed Victorian house in Bertram Street was £5,400. “It will save 650kg of CO₂ per annum, which equates to £8 per kg of CO₂ saved”. But he expects this to come down. “This was a prototype for us so we expect to reduce the cost and time. Eventually we should reach about £5 per kg.” This would give a whole-house cost of around £3,200.

United House has been approached by large retailers already involved in offering domestic retrofit programmes, such as Sainsbury’s, M&S and Tesco, as well as wealthier, eco-conscious home-owners with draughty older properties. Sivill estimates three-quarters of the market will eventually be for private homes.

Sivill also has his eye on cavity wall properties that have had their cavities filled. To bring a solid wall up to Part L 2010 standard means achieving a U value of 0.3W/m²K, but recognition that cavity walls are harder to insulate means that only 0.5 is required. “Cavity wall insulation is not that good,” says Sivill. “To get to 0.3, you’ll need to combine it with thinner internal wall insulation.”

External insulation panels can improve the kerb appeal of properties as well as reducing heat costs