In recent years, energy assessment methodologies such as SAP and RdSAP have encountered numerous delays, often caused by incomplete or late test cases. Earlier this year, the Home Energy Model consultation proposed a number of changes to the current delivery model, introducing Energy Calculations as a Service (ECaaS). While this new delivery model offers the potential for numerous benefits, it may also present significant challenges.

Background

At present, all SAP and RdSAP software applications are required to build a calculation engine based on the SAP specification and to match a range of example dwellings, known as ‘test cases’, supplied by BRE. This model allows for sufficient peer review of the methodology by schemes and allows the methodology to become more robust over time.

However, in recent years, both SAP and RdSAP have suffered roadblocks due to incomplete or late test cases. This has resulted in significant delays to applications and, in the case of RdSAP 10, a delay to the implementation of the methodology.

The Home Energy Model

The Home Energy Model consultation, published earlier this year, proposed a number of changes to the delivery model of applications used for generating compliance reports and Energy Performance Certificates (EPCs).

In this new delivery model, a version of the Home Energy Model engine will be hosted on a cloud-based government service. Data from schemes’ user interfaces will then be sent to the engine to generate the relevant compliance results. This process is called ‘Energy Calculations as a Service’ (ECaaS).

The first official use of ECaaS will be to generate compliance results for the Future Homes Standard, expected in 2025. It is then expected to be used for the calculation of EPC ratings for both new and existing homes in the future. ECaaS will only be available to approved energy assessor accreditation schemes, such as Elmhurst.

There are a number of potential benefits and challenges of this delivery model. These include:

Potential benefits:

• Consistent Results: This delivery model removes the possibility of different applications providing different compliance results.
• Resources to Deliver Applications: As applications will no longer need to develop an engine and match relevant test cases for approval, this model will provide greater scope to produce a better user interface.

Potential challenges:

• Management of Downtime: If the service requires any maintenance downtime after implementation, assessors would not be able to calculate compliance results. If this is unavoidable, further information is needed on how this would be communicated to schemes so they can notify members.
• Lack of Industry Peer Review: Although the version of HEM that will be used for ECaaS is published in open-source code, it may be very difficult to understand the calculation engine unless you are able to interpret code.
• Calculation Speed: The time it took to calculate compliance results in the BRE HEM: Future Homes Standard Consultation tool was sometimes 10 minutes. This is not sustainable for the industry. Although the version of HEM used for ECaaS will likely be much faster, it is unlikely to be instant, as per the current SAP/RdSAP applications.

Elmhurst Thoughts:

Elmhurst continues to maintain regular contact with the Ministry of Housing, Communities, and Local Government (MHCLG) regarding the development of ECaaS. This remains a key component of the Home Energy Model and is of particular interest to Elmhurst, as its progress will directly influence the development of our own HEM application.

We expect further details shortly on how the service will operate and when schemes can begin testing. Elmhurst will keep members informed of all updates.