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According to the UN, carbon emissions from constructing and operating buildings hit a record high in 2021, contributing 37% towards the global carbon.

Some countries, including the UK, are implementing policies to reverse this trend with some success although much of this can be attributed to the decarbonisation of the electricity grid rather than improvements in building energy efficiency.

Delivering net zero buildings and retrofitting existing ones is a going to be a huge job. 鈥淣et zero carbon is likely to be the biggest challenge our industry faces in the next generation,鈥� says Simon Wyatt, sustainability commissioner at Cundall and 黑洞社区 the Future commissioner.

Drivers for change

For many years building regulations, namely Part L, has been the primary driver for controlling carbon emissions from buildings. After a long hiatus without any change Part L was revised last year and the next iteration, scheduled for 2025, will see gas boilers in new buildings banned and carbon reductions of 75%-80% for new homes.

Large corporates are increasingly setting themselves net zero targets and want to occupy low carbon buildings.

>> Click here for more on the 黑洞社区 the Future Commission

This has trickled down into the construction industry so developers are adopting net zero targets and expect their supply chain to do the same, meaning the industry has get to grips with net zero.

Helpfully, organisations including the UK Green 黑洞社区 Council, RIBA and LETI are publishing targets and guidance to help the industry on its journey. The commission can help collate thinking and highlight solutions around this.

Challenges for new buildings

The problem with Part L is that while it sets a theoretical carbon target, it does not represent how much energy a building uses. The difference between predicted and actual performance 鈥� the so called performance gap 鈥� is often huge with buildings consuming far more power than anticipated.

Clients are notoriously shy about publishing performance data, leaving the industry stymied in its bid to improve building performance. 黑洞社区s constructed to the Passivhaus standard perform as expected, driving its use.

As carbon calculation methodologies are at an early stage these can lack consistency and there are glaring gaps in our knowledge of the embodied carbon content of some building elements

It is now being adopted as the building standard for new homes in Scotland. And NABERS, a performance standard which has driven results in Australia is gaining traction here due to a robust design and review methodology including 12 months of operational energy data prior to certification.

NABERS offers great potential but it will take time for the industry to familiarise itself with it and a database of benchmarks of different building types to be created.

The net zero agenda is focusing attention on the carbon embodied in its construction and subsequent maintenance and refurbishment. This presents a big challenge as embodied carbon has no history of regulation, which means most people have barely given it a second thought.

In the absence of any legislation LETI has published embodied carbon targets for a range of building types which are being embraced by some of the bigger developers and consultants.

As carbon calculation methodologies are at an early stage these can lack consistency and there are glaring gaps in our knowledge of the embodied carbon content of some building elements including services. And there is very little verification of the embodied carbon of finished projects with much of the action fuelled by enthusiasm and good will.

In terms of regulation the London Plan requires whole life carbon calculations for large projects to enable the creation of a database that can be used to set mandatory targets in the future. Currently, there is nothing at national level other than the proposed Part Z which has been drawn up by the industry in the style of a new building regulation for embodied carbon. Promoted by large industry organisations, the question is how small developers and builders will cope with this should it be adopted.

The biggest challenge is funding. Net zero buildings command a premium as the materials are expensive, there is more work involved and there are a limited number of organisations with the skills to deliver them. Construction inflation is already impacting on project viability which inevitably means net zero aspirations will be squeezed.

Challenges for existing buildings

Reducing emissions from existing buildings is a huge challenge because 80% of the buildings that will be around in 2050 already exist. And many of those were built in the days before energy regulation and leak energy like sieves 鈥� some 30% of the UK鈥檚 emissions come from buildings with 79% of that derived from heating.

The biggest challenge is funding improvements. Retrofitting insulation is notoriously disruptive, expensive and difficult so most people do not bother, even in an era of sky high energy bills.

>>See also: Sustainability: Estate decarbonisation

>>See also: How to retrofit a historical building: the challenge and solutions

The climate change committee (CCC) estimates it will cost 拢360bn to retrofit Britain鈥檚 buildings with 拢250bn needed for homes. People want the government to pay but the scale of the cost means building owners will probably need to foot most of the bill. The CCC says retrofitting the average home will cost 拢10,000 with 63% of homes needing an investment of just 拢1,000.

Retrofitting the average home will cost 拢10,000 with 63% of homes needing an investment of just 拢1,000

That means the remaining 27% require an average of 拢25,324 a sum that will be at best unpalatable and at worst unaffordable for many home owners. Various incentive schemes have been tried and failed because of high costs and poor administration.

Strengthening government policy

Delivering net zero buildings and a national retrofit programme needs the industry needs to skill up and recruit an army of retrofit installers. Attracting sufficient numbers into the industry and training them up is a massive challenge.

Achieving net zero is not helped by confusing and weak government policy. Good at grand policy announcements such as the 10-point plan for an industrial revolution, the government has a poor track record for delivery. This has not helped policy confusion because the Department for Levelling Up, Housing and Communities is responsible for building regulations while the Department for Business, Energy & Industrial Strategy oversees energy policy.

This disconnect makes producing consistent regulation more difficult. And for years some local authorities have demanded higher energy efficiency standards than those in the building regulations, which is confusing and turns energy regulation into a postcode lottery. Meeting these challenges is a huge task but must be done to avoid catastrophic climate change in the future.