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Blog Post 5 March 2021

Going beyond energy efficiency to challenge climate change

Ahead of International Women’s Day, we spoke to Emilie Carmichael, our head of international collaboration, about her experience of completing a major home renovation with the climate emergency in mind.

By including several energy efficiency improvements, solar PV panels and a low carbon heat pump, Emilie’s redesign has gone beyond the minimum building regulations now required as she looks ahead to complete decarbonisation by 2050.

Here, we share how she has chosen to challenge climate change by minimising her household carbon footprint, installing insulation, solar powered shutters and a heat pump – and coming off the gas grid along the way.

The first phase: energy efficiency

When Emilie and her husband bought their house in 2009, it needed a full renovation, including replacing the existing 40-year-old boiler. In the process of installing a new washing machine, the gas supply to the boiler was shut off – and failed to come back on. For the next two years, they lived with no central heating and relied on an immersion heater for hot water and oil radiators for heating.

The first phase of the renovation was to replace the heating system – with the gas pipes and electrics moved to make space for a future loft conversion. During this stage, Emilie made sure the house was as energy efficient as possible. The property is a 1940s semi-detached, cavity wall home, but they added more insulation than building regulations required at the time.

While Emilie considered installing a heat pump at this stage in the renovations, they couldn’t stretch their budget to cover the upfront cost. However, they opted for an energy efficient boiler with water tank, which would be compatible with solar thermal, with a view to installing such a system later. The boiler they chose works best when running almost constantly; it’s regulated by the outside air temperature to ensure the house maintains a certain temperature. It also requires oversized radiators that run at a lower temperature, which are also better suited for use with a heat pump.

They replaced all lights in the house with energy efficient LED bulbs.

A change of direction

In 2012, Emilie’s Mum became a tetraplegic, so the original plan to build a loft conversion was changed in favour of a prefabricated ecostudio in their garden, where her Mum would be able to stay. When Emilie’s Dad, who had been primary caregiver, passed away in 2017, her Mum came to live with Emilie in the studio in London. To allow her Mum to access the ground floor of the main house, including the kitchen and a bathroom, another renovation was needed.

At this point, Emilie and her husband had to choose between pushing ahead with the original plan to install solar thermal heating or coming off the gas grid and installing a heat pump. They bit the bullet and opted for a heat pump, seeing it as a last chance to include the work in a major renovation project. The Renewable Heat Incentive (RHI) was a factor in Emilie’s decision to install a heat pump, with ongoing payments able to help pay back the upfront cost over several years.

Working at Energy Saving Trust, Emilie’s involvement with European energy policy – as well as her position as vice president of the board of ECOS, the Environmental Citizen’s Organisation for Standardisation – has made her increasingly aware of the opportunity to go beyond energy efficiency and work towards a circular economy. The goal of the next renovation project was twofold: Emilie wanted to make it as energy efficient as possible, but also to make it as accessible as possible for her Mum.

Underfloor heating systems are compatible with air source heat pumps.

Considering the carbon impact

The aim was to redesign the ground floor of the house in a flexible way – so that areas could be easily adapted in the future if circumstances changed. While their new boiler and tank weren’t compatible with a heat pump, Emilie was able to sell them to a new owner, giving them a second lease of life and encouraging a reuse economy. They also chose to reclaim and reuse as many existing house materials for the renovations. When buying new products or materials for the house, Emilie and her husband considered more than just their energy efficiency credentials, but also looked at their embedded carbon – and have tried to use the lowest carbon materials available.

Many insulation products, for example, use petrochemical-based blowing agents, meaning they have more embedded carbon than sheep’s wool, which Emilie opted for. They also tried to minimise the use of PIR insulation board, found an alternative to concrete for the foundations, and reused the oversized radiators, which work efficiently with a heat pump.

The house has been clad with wood, which is a low carbon impact material, reflecting the design of the ecostudio in the garden. The cladding was sourced locally to avoid the carbon emissions associated with transporting materials from outside the UK. The new design incorporates a ‘green roof’, which has insulating properties and creates a small haven for nature. The Velux rooflights are fitted with solar-powered shutters, which can be closed at night to keep the warmth in, or during the day to keep the heat out.

They considered the embedded carbon in the insulating material they used in the renovation.

Looking to 2050 and decarbonisation

Their new low carbon heat pump is powered by solar PV panels, and controlled using a high spec set of heating controls. While Emilie and her husband applied for the UK Government’s Green Homes Grant scheme to help cover the upfront cost of the heat pump, they had to progress with the installation before a voucher was issued. They will be able to recover some of the upfront cost over the next 7-8 years through RHI payments.

When choosing energy efficient appliances for the renovated rooms, Emilie also had to consider accessibility. For example, she only found one oven that was both energy efficient and that her Mum could use without assistance. In the future, they’re hoping to purchase an electric vehicle (EV), however have found that very few EVs are currently suitable for wheelchair users. After researching when adapted electric cars might become available, Emilie discovered that it’s proving difficult. In electric vehicles, the battery is fitted into in the base of the car, which is where the floor typically needs to be dropped to adapt a vehicle for a wheelchair user.

Emilie’s renovation project has gone beyond the minimum regulations related to energy efficiency in buildings – whether by installing more insulation than is typically required to coming off the gas grid. The process of disconnecting from the gas grid was more complicated than they had anticipated, and there was an unexpected additional cost to pay for an engineer to cut off the gas supply, which is something that should be addressed in the future to encourage more households to switch away from gas to low carbon heating technologies.

Emilie is now looking to 2050 as the year by which we must have completely decarbonised domestic heating and hot water, which currently makes up around 77% of total household carbon emissions. In this project, she has challenged the status quo by going beyond the minimum currently required to tackle climate change, doing as much as possible within financial constraints.