Home Energy Model: 5 things housebuilders & installers need to know

There is still time to prepare. SAP remains the compliance methodology for now, with HEM expected to be introduced from 2027. Understanding what is changing now will help housebuilders, developers and installers prepare for the transition.

Here are five things housebuilders and installers need to know.

1. HEM will change how heating systems are assessed

SAP was designed for a very different housing and energy landscape. It was introduced when gas boilers were the dominant form of heating and technologies such as heat pumps, solar PV, batteries and smart controls were far less common.

HEM has been designed with today's technologies in mind. It uses more detailed modelling to assess how a home uses and generates energy over time.

This means decisions made during the design and specification of a home will have a more measurable impact on its assessed performance. Heating systems, building fabric, glazing, airtightness, controls and renewable technologies all form part of the picture.

The heating system cannot be considered separately from the building around it. How the different elements work together will become increasingly important.

2. A whole-house approach will become more important

HEM considers a wider range of factors, including the building's fabric, heating system, controls and renewable technologies. Decisions around insulation, airtightness, glazing, orientation and heating provision can all affect the final assessment.

This makes coordination between different parts of a project more important.

For housebuilders, the choice of heating system cannot be considered in isolation from the building it is going into. Working with designers, manufacturers and installers early in the process can help ensure that the different elements of the home work together.

A heating system needs to work with the building around it. Understanding how the different elements fit together will become increasingly important as HEM is introduced.

3. The detail behind the installation will matter

One of the biggest differences between SAP and HEM is the level of detail involved.

HEM is designed to model a home's energy performance on a half-hourly basis, rather than relying on monthly averages. It can therefore take greater account of how technologies perform and interact under different conditions.

So, accurate information will matter more. This level of modelling creates a greater need for accurate information. Product data, heating system specifications and details about the building will all contribute to the assessment.

Manufacturers and installers will have an important role in making sure the right information is available, while housebuilders and developers will need to consider how that information is gathered and used during the design process.

Getting the specification right from the outset could also help reduce the risk of changes and compliance issues later in the project.

4. You don't need to install to a future standard today

The Future Homes Standard is due to come into force in March 2027, but SAP will still be used at that point. HEM is expected to be introduced no earlier than three months after the Future Homes Standard, with SAP and HEM then running alongside each other for a transition period.

For projects being designed and delivered now, it is important to understand which requirements actually apply.

At the same time, preparing for HEM does not mean waiting until it becomes mandatory. Good energy efficiency, appropriate system design and a whole-house approach are unlikely to become less important.

5. The decisions made now will shape future projects

The transition is likely to bring energy performance further into the design and specification process. Choices around the building fabric, heating system and other technologies will increasingly need to be considered together.

It is worth considering:

• Current compliance and design strategies

• Heating system choices and how they work with the rest of the home

• The performance of the building fabric

• The quality and availability of product and system data

• How designers, assessors, housebuilders and installers work together

There is more detail to consider than we can cover here. VN Solutions is also developing technical guidance on the transition, with more detail on what HEM means for heating specification, system design and the performance of new homes.

In the meantime, VN Solutions can help you select integrated low carbon heating solutions designed to perform under tomorrow's standards.

Speak to our team to discuss your next project or visit our website to learn more about our complete heating solutions.