Why are we still using gas to heat our buildings?

With the UK pledging to achieve ‘Net Zero Carbon by 2050’, Thomas Vazakas, Technical Director for Energy & Sustainability, poses the question “why we are still using gas to heat our buildings?”

Have you ever wondered why we are still using gas to heat our buildings? We all know that gas is a depleting fossil fuel, that its production and consumption is not good for the environment and that it pollutes the air quality in our cities.

Over recent years many industries that historically relied heavily on fossil fuels have begun evolving with a shift to renewable and more environmentally friendly power sources. The automotive industry for example has invested in developing electric alternatives to such an extent that electric vehicles are now expected to become the norm in the short-term future.

However, we continue to design buildings to be powered using gas not electricity, why? There is a simple answer to this, but thankfully we may now be on the verge of change.

Until very recently, electricity had a higher carbon intensity compared to gas. However, through the introduction of renewables and a reduction of the use of coal and gas, the carbon intensity of electricity has more than halved since 2012 - now very similar to gas. Moreover, it is projected to fall by an additional 50% or more by 2030; signalling the time to switch from gas to electric heating is approaching fast.

The UK Government just announced its commitment to achieve Net Zero Carbon by 2050. The plan is based on the ‘UK housing: Fit for the future’ report, which was produced by the Committee for Climate Change [CCC]) in February 2019 and recommends that from 2025 - at the latest – there should be no new homes connected to the gas grid. Instead, the report recommends, all new homes should be heated through low-carbon sources, such as electric heat pumps and heat networks.

Drastic? I would argue appropriately so. However, not unrealistic as there is evidence to show that such a policy can be both implemented and delivered. The Netherlands have been doing this since July 2018.

In July 2018 the UK government published the updated carbon emission factors (SAP 10), recognising that grid electricity has significantly decarbonised since the last update of Building Regulations Part L (April 2014).

The impact of these new emission factors is significant; meaning that technologies generating on-site electricity (such as gas-engine CHP and solar PV) will no longer achieve the carbon savings they have to date. It’s therefore anticipated that developments will need to utilise alternative or additional technologies to meet their energy and sustainability targets such as using zero emission or local secondary heat sources (i.e. electric heat pumps).

However, these new emission factors will not be incorporated into the Building Regulations until after the Government’s consultation process - likely to happen in late 2019 or 2020.

Recognising the impacts of this delay, the Greater London Authority (GLA) has released its own ‘Energy Assessment Guidance’ (October 2018) to ensure planning applicants use the updated carbon emission factors to estimate CO2 emission performance until the updated Building Regulations come into effect.

Favouring the use of electricity over gas, these emission factors effectively make it unjustifiable to use gas boilers or gas fired CHP for any project in London once proposed emissions are compared to emissions of the same project using electric heat pumps.

As a result, GLA has rejected most, if not all, planning applications with an energy strategy based on gas boilers or CHP since the beginning of the year. As it stands, GLA is the only authority who is actively pushing for this, however many Local Authorities, especially in large metropolitan areas, are expected to follow London’s example and update their policies in the near future.

The switch from gas to electric will not be an easy task. For designers, builders, developers and building users, it will take time to learn and adjust to electric heating systems. Moreover, the switch to low-carbon heating (e.g. heat pumps or hydrogen gas) is expected to be expensive in new homes and non-residential buildings. According to CCC, ultra-high energy efficiency standards, installed alongside an electric air source heat pump, represent a 1.1-4.3% uplift on build costs relative to current standards, depending on the type of building. The good news is that these costs are expected to go down as more systems are installed over the next few years.

Arguably, the most difficult implication of the switch is the lack of compatibility. Electric heat pumps typically operate in lower temperatures than gas-fired heating systems, meaning any future developments using electric heating would not be able to connect to an existing District Heating Networks (DHN), even if they are built within the network.

Despite this, the switch from gas to electric will happen sooner than most of us anticipate. This is fundamental if the UK is to meet its Net Zero Carbon target by 2050. Replacing gas boilers and CHPs with electric systems is undoubtedly a step in the right direction with the environmental, economic and health benefits outweighing the challenges. I therefore look forward to a time, in the hopefully not so distant future, where our buildings use a cleaner fuel and the air quality in our cities improves because of it.

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