The benefits of a ‘whole-building’ approach to installing heat pumps
This piece was originally published in Energy Manager Magazine, March 2025
Author: Jordan Noffke, energy and carbon analyst, Salix
Decarbonising the buildings sector is a key task in our responsibility for tackling the climate crisis. At Salix, we’re privileged to work alongside governments across the UK to deliver energy efficiency schemes and help navigate the ambitious net zero targets.
Whilst the UK overall has committed to reach net zero by 2050, Scotland has set its headline task of reaching net zero by 2045 - a full five years ahead of the wider UK target of 2050.
And as the Scottish Government notes [1], the buildings sector contributes up to 40 per cent of all the UK’s carbon emissions. It is clear that emissions reduction should be high on the priority list for every building energy manager.
Although a lot has already been achieved, there is a long way to go.
Our teams are proud to work on delivering inspiring net zero projects in Scotland. We’ve supported Scottish Government to deliver a number of energy efficiency schemes over the years. These have included, the Scotland Recycling Fund, Scotland’s Public Sector Heat Decarbonisation Fund, The Scottish Public Sector Energy Efficiency Loan Scheme and Scottish Funding Council schemes.
We are committed to supporting organisations to consider their buildings when addressing climate change issues.
As a key part of government policy via building regulations is the conservation of fuel and power. In recent years (for example, the February 2023 Energy Standards in Scotland[1]), updates to these building regulations have further emphasised the importance of a whole-building approach to reduce energy demand before energy sources are decarbonised.
Standards are set that certain elements of the building fabric must meet when they are renovated, including by specifying minimum U-values and basic insulation improvement measures to take. In the context of decarbonising a building’s energy use, a whole-building approach looks beyond the single component of the heat pump, instead prioritising factors such as insulation, air tightness, ventilation, and the thermal performance of windows, walls, and roofs.
In many cases, interventions here can be incredibly cost-efficient.
As part of my work at Salix, I am heavily involved in the Public Sector Decarbonisation Scheme. This is a highly popular funding programme for England which we’ve been delivering on behalf of government since 2020. Our webinars and guidance strongly emphasise the importance, indeed, necessity, of a whole-building approach.
It’s something we talk about all the time across the sectors.
Whilst I’m sure many of our readers will be aware of the importance of a whole-building approach to installing heat pumps, for example, to enable lower flow temperatures, and of course our regulatory responsibilities, I would argue that implementing net zero in the buildings sector via a whole-building approach is both more nimble and more reliable at reducing emissions.
A whole-building approach can help mitigate the ‘rebound effect’. The rebound effect is a known behavioural phenomenon that is often associated with efforts to improve sustainability. It refers to a tendency for gains from improvements in efficiency to be lower than expected. The most often cited reason for this is that the cost reductions brought by a technological improvement or efficiency improvement are negated by usage increases that take advantage of this cost decrease, thereby negating some of the consumption reductions.
In the case of an office that might attempt to save energy by reducing the internal set-point temperature of its heating system, a new heat pump might encourage its occupants to raise the set-point temperature slightly to a more comfortable level, their guilt about any planetary impact assuaged by the heat pump’s climate-friendly credentials. A whole-building approach that replaced the office’s leaky single-glazed windows with new double-glazed units would reduce the total energy demand of the building and help offset any carbon emissions increased associated with a higher set-point temperature.
Taking a country-wide view, a whole-building approach helps mitigate any delays to grid decarbonisation. While heat pumps produce no direct emissions, there may still be emissions associated with the electricity they consume.
As noted by the Treasury’s Green Book, the carbon factor for the UK’s grid in 2024 is about 0.15kgCO2e/kWh [2], which is expected to decrease to 0.05kgCO2e/kWh by 2030. This is a significant fall that requires a very rapid addition of renewable generation capacity over the next five years. The UK has decarbonised its grid very rapidly recently, but there are still bottlenecks, particularly around planning permission for large renewables installations, and for grid connections. While renewable-only tariffs are an option for an organisation counting its Scope 2 carbon emissions, reducing energy demand is a sure way to reduce emissions at source and mitigate any slow-down in the grid’s decarbonisation. A building that installs cavity wall insulation to reduce its overall heat demand alongside a new heat pump will end up saving more carbon – and faster – than a building that installs only a heat pump.
Those of you who have installed equipment that has radically increased the electricity consumption of their buildings will likely have encountered the issue of upgrading your site’s electricity supply. Our experience at Salix in delivering the Public Sector Decarbonisation Scheme indicates that delays in electrical connection upgrades can, at times, hit building decarbonisation projects unawares.
Distribution Network Operators (DNOs) face long queues of connection upgrade requests as building occupants race to decarbonise their sites. A heat pump installation can easily double the power required by a building at peak load. It is not unusual for capacity upgrades to take upwards of two years from initial inquiry to the point of connection.
A whole-building approach could reduce the total size of the heat pumps required, which could in turn increase the amount of heat pump capacity that can be installed without an electricity supply upgrade. It’s not quite skipping the queue, but realising you no longer need to be in it.
A whole-building approach to reducing energy demand before the installation of a heat pump has clear cost benefits and is promoted by government guidance, but brings carbon reduction benefits beyond these, including mitigating the rebound effect and any slowdown in grid decarbonisation, as well as potentially reducing the reliance on Distribution Network Operators to deliver electricity upgrades to decarbonise.
What’s the saying – change starts at home?
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