Prioritising Fabric First Measures Before Heat Pump Installation 

It is widely accepted amongst the scientific community that we are now in a climate emergency. A fundamental reason for this is due to the greenhouse gas (GHG) emissions created through our human activities as a society. A major GHG contributing to these emissions is carbon dioxide (CO2) which is released when oil, gas, and coal are burned. 

The Public Sector Decarbonisation Scheme (PSDS) aims to reduce GHG emissions from public sector buildings by 75% by 2037, compared to a 2017 baseline. In 2024, the Department for Energy Security and Net Zero (DESNZ) confirmed Phase 4 of the PSDS, which will be overseen by Salix Finance. The funding allocated for this phase amounts to £1.17 billion, as confirmed in December 2023.  

This latest phase presents a significant opportunity for the government and local authorities, in England, to decarbonise non-domestic, public-sector buildings by installing heat pumps (HP). Unlike traditional gas boilers, heat pumps utilise electricity to heat buildings, which can contribute to emissions reduction efforts. Moreover, with the ongoing expansion of renewable energy sources such as wind and solar power in the UK, HP could play a crucial role in achieving emission reduction targets. In addition, more recent research has shown that ‘fabric first' measures would make the implementation of HP even more effective.  

What Are Fabric First Measures? 

In general, fabric first measures involve designing buildings with excellent thermal efficiency, which helps to reduce the need for heating (and cooling). The less energy required to heat a building, consequently, leads to fewer emissions. When considering HP and fabric first measures, various strategies can be implemented to enhance the building's heat-retention properties. There are several principles of fabric first: 

• Maximising Air Tightness: Ensuring that the building envelope (walls, roof, windows, etc.) is well-sealed to prevent air leakage. This minimises heat loss or gain due to drafts. 
• Optimising Solar Gain: Utilising natural sunlight to passively heat the interior spaces. Proper orientation and window placement play a crucial role. 
• Increasing Insulation Levels: Enhancing the thermal performance of walls, roofs, and floors by using high-quality insulation materials. 
• Optimising Natural Ventilation: Designing for effective airflow without relying solely on mechanical ventilation systems. Reducing the air leakage of the building. 
• Using Thermal Mass: Leveraging the ability of building materials to absorb, store, and release heat. For example, materials like concrete or stone can help regulate indoor temperatures. 
• Older buildings are not always well insulated. However, implementing some of the above fabric first principles could help increase the insulation and the effectiveness of HP. 

Why do Heat Pumps Suit Fabric First? 

Unfortunately, due to the price of electricity (relative to gas), HP are costly to capital and revenue budgets. If a building is not insulated according to a fabric first approach, a larger HP will need to be installed. This therefore increases the capital cost of the HP as larger HP are more expensive. By insulating the building, the peak heat demand can be brought down, allowing a smaller HP and therefore reducing capital costs. In some cases, the additional costs associated with fabric improvements can be offset by the reduction in peak heat demand, allowing overall costs to be reduced. The reduction in the size of the HP can also have additional benefits such as decreasing costs associated with the electrical supply.  

Upgrading the building fabrics, in some cases, can result in radiator modifications not being required for the system to operate with a HP compatible flow temperature (35 to 55°C). This again can mean that costly heating system modifications are avoided, and so overall costs are reduced. 

Improving insulation allows heat to stay in the building more easily. This can be particularly beneficial if variable-price electricity tariffs are used with the building. This works by not heating the building during peak electricity price periods. This, in turn, benefits the grid and decarbonisation by reducing the peak electricity demand (which is often provided by gas power stations).  

Public Sector Decarbonisation Scheme and Fabric First  

The next phase of the PSDS scheme will move to a more targeted method of allocating funding to ensure emissions are being cut most effectively. Projects delivering the best value for money based on the most direct carbon emission reductions will be prioritised during assessment. Therefore, the implementation of fabric first in combination with HP could significantly increase the chances of projects to be prioritised by the government scheme and having access to funding. The government expects to publish guidance for Phase 4 of the PSDS in Summer 2024 and this may bring the UK closer to achieving its goal of net zero by 2050.  

How we can help you 

While fabric first improvements for buildings offer significant potential for enhancing energy efficiency, in combination with HP, it is important that each building is treated as being context-specific. Approaches must be sensitive to the building's historical significance, structural integrity, and the surrounding environmental conditions.  

We have the expertise to guide you through these intricate considerations, offering tailored solutions and maximising funding opportunities. 

If you would like us to help you with a decarbonisation project with or without the Public Sector Decarbonisation Scheme, please let us know and contact us at:?info@tomsonconsulting.co.uk??