We’ve known for a long time that the fabric-first approach maximizes building energy efficiency and minimizes carbon impact. NorDan UK Ltd architecture and window expert Tom O’Sullivan reminds us of the principles of fabric first, and how coming changes in building regulations look set to finally deliver on this ambition

The approach to building design is to maximize the performance of the components and materials that make up the building structure rather than relying on post-construction additions such as photovoltaics or energy-saving technology.

The fabric first uses methods such as maximizing airtightness, optimizing insulation, eliminating thermal bridges, optimizing solar gains (the increase in temperature by solar radiation) and natural ventilation, and the use of thermal mass (the ability of a material to absorb, store and release heat) of the building fabric.

Over the lifetime of a building, this is a cost-effective way to save carbon and provide energy efficiency, as opposed to simply adding new solutions after construction.

Members of the radical Insulate Britain movement against climate change and energy poverty have shown themselves ready to take things to the next level – closing motorway intersections, demanding that “the government improve the insulation of all housing in the UK by 2025 and renovate all homes”. with better insulation by 2030”.

These are extreme acts for what looks like a mundane request, but if this target were met, it would help reduce the 15% of total UK emissions from heating homes.

Building energy efficiency has also become a national security issue, with the government launching its UK Energy Security Strategy in April this year.

The document sets out plans to build on the Prime Minister’s “Ten Point Plan for a Green Industrial Revolution” and the “Net Zero Strategy”, and “Comes in light of rising global oil prices energy, caused by the increase in demand after the pandemic as well as the invasion of Ukraine by Russia.

The strategy includes almost £1.8bn earmarked for low-income households through the Home Renovation Grant and the Social Housing Decarbonisation Fund, to help put in place energy efficiency measures, and is expected to improve up to 500,000 homes.

To date, building legislation and regulations have not applied fabric first, but it is suggested that it be included in the Future Homes and Buildings standard, due to be implemented in 2025, setting standards for all future buildings.

The Future Homes and Buildings standard outlines changes to Part L (Fuel and Energy Conservation) and Part F (Ventilation) of the Building Regulations to ensure that all new homes in England are energy efficient. time-tested with low-carbon heating systems and high levels of energy efficiency.

The new standard is expected to reduce total carbon emissions from buildings by 75-80%

The full technical specifications of the Future Homes standard will be seen in 2023, with legislation and implementation by 2025.

As an interim step, announcements of Part L changes are set to come into effect in June this year, which will ensure that all new homes produce 31% fewer carbon emissions, a step that will have a significant impact on specification decision-making.

For windows, this will affect the maximum allowable u-values ​​of glazing products.

U-values ​​are a measure of heat loss through a material, and they are used to measure the effectiveness of elements of a building’s fabric as insulators; that is, their effectiveness in preventing heat from passing from the interior to the exterior of a building. With u-values, the lower the number the better.

The current maximum allowable figure for windows is 1.6 W/m2K, but in June it will be reduced to 1.2 W/m2K, and it is suggested that this figure will drop to 0.8 W/m2K in 2025.

What does this mean for those who specify windows?

Heat is not only lost through the glazing itself, but also through the frame, and some materials are better at preventing heat transfer, so lend themselves to lower u-values.

In general, PVCu, aluminum and composite windows can only achieve a u-value of 1.2 by being triple-glazed and most are unable to achieve a u-value of 0.8 points. High-quality timber-framed windows are another story. They are capable of achieving a u-value of 1.2 with double glazing and a u-value as low as 0.65 with triple glazing.

As well as superior thermal performance, the NorDan system offers incredible air permeability figures, with double or triple glazed windows opening inwards or outwards reaching less than 0.1m3/m2h at 50 Pa for air leaks. This is useful for Passiv specification projects, reducing heating costs and tackling fuel poverty.

Many window manufacturers need to make significant adjustments to their products to meet this year’s U-value reduction, with some requiring a complete overhaul to meet the changes expected in 2025.

The decision to choose windows has become more complex than simply opting for triple glazing, because it is possible that a double-glazed wooden window will perform better, cost less and have a significantly longer life than PVC triple glazing.

At NorDan we have met the standards set by Part L for many decades as our windows are designed and tested to exceed UK standards for weather performance.

Why the outperformance? Because NorDan products were originally designed for the harsh Norwegian maritime winters.

From thermal bridging to air permeability and thermal transmittance, NorDan’s products meet Passivhaus standards, and our typical double-glazed windows are best in class, meaning we can easily achieve the change in standards expected for 2025 today.

In fact, we have been the first fabric option for architects, specifiers, property developers and contractors for many years now, and are increasingly working with new clients who realize that the products they have historically chosen will no longer meet the required standard. .

Fortunately, NorDan’s in-house specification team works with customers to navigate new regulations, with early engagement reducing costs, ensuring compliance and tight specification, and ensuring customers get what they want. at the best possible price.

Tom O’Sullivan

Technical Specifications Advisor

United Kingdom

www.nordan.co.uk

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