Housing Energy Model:

A Tool for Policy Makers

HEM is a housing energy model designed to support domestic carbon and energy policy formulation, carbon foot-printing and roadmap formulation, strategic or concept low carbon design, carbon and energy performance rating, and cost effective improvement identification. The program can be applied at National housing stock level, community or Local Authority level or to individual dwellings.

HEM is based on dynamic simulation, which allows more detailed insights into building performance than more simplified methods and can be easily adapted to handle new technologies or legislative contexts. HEM was originally developed for application to the Scottish housing stock, has since been applied at other scales and may readily be adapted for other contexts.

HEM has an underlying array of simulation-derived models configured to represent the range of thermodynamic performance observed in the housing stock. An appropriate model is selected using fabric and system determinant parameters inferred from simple inputs and embedded inference logic. The array can be simulated for any number of different contexts such as climates (including future climates) or indoor environmental quality expectations.

Examples of some typical applications to date follow.

National housing stock fabric upgrade strategy HEM was used to evaluate fabric upgrading strategies for the entire Scottish housing stock based on the underlying simulation models representing current and likely future states for the principal design parameters that are relevant in the Scottish context. In addition, the project assessed the impacts of the deployment of small-scale renewable technologies and low energy appliances. Local authority/community upgrade strategy and carbon roadmap formulation The HEM methodology was used to evaluate the energy and carbon footprint of Local Authority and Registered Social Landlord housing stocks. Possible upgrades were established appropriate to each property type and the impact evaluated. These upgrades include different levels of fabric, fuels (including biofuels), heating systems and renewable energy options. Carbon and Energy performance and upgrade strategy for individual dwellings The energy and carbon footprint of individual dwelling (including heating, hot water, lighting and appliances) was inferred through application of HEM, allowing different upgrade strategies to be developed. The tool allowed individual upgrade possibilities to be compared in order to select those that offered best value. Energy labelling in compliance with the EU Energy Performance of Buildings Directive HEM was applied on behalf of the Scottish Building Standards Agency to meet the requirements of the EU Energy Performance of Buildings Directive, which calls for the issuing of performance certificates. When used by SBSA, HEM is known as the Scottish Energy Rating Tool, or SERT. Within the project, the HEM predictions were shown to be well aligned with the Government’s simplified domestic sector method known as SAP. Domestic controls performance evaluation HEM was applied on behalf of the UK Building Research Establishment to undertake an evaluation of the impact of controls on energy and carbon performance for a range of UK dwelling types, heating and hot water system types and control options.

HEM access:

download
manual

Old JAVA tool:

form and fabric upgrades
small scale renewable energy systems
energy efficient appliances