The purpose of this guidance note is to provide a background to the calculation methodologies underpinning the energy performance section in the HQM ‘Energy and Cost’ issue.
The purpose of this guidance note is to provide a background to the calculation methodologies underpinning the energy performance section in the HQM ‘Energy and Cost’ issue.
As its name suggests, the HQM is focussed around delivering quality homes. When looking to purchase or rent a new home, consumers look for quality, and also for particular features specific to their needs (e.g. location, size, specification etc.). The HQM standard reflects these needs by promoting a holistic approach to assessing homes and reporting on specific attributes of a home. This enables consumers to make informed decisions and allows developers to showcase and differentiate their product in the marketplace.
This document is intended to give a technical background to the calculation methodologies underpinning the HQM ‘Energy and Cost’ issue for end users (e.g. assessors, consultants or others) needing to make decisions influencing a home’s HQM score of the issue. It explains how the methodology works, the HQM inputs required and each of the outputs generated. It also provides guidance on how variations in the input (i.e. SAP inputs, ‘bolt-on’ inputs etc.) affect the outputs. The principles of the calculation methodologies used in the Energy and Cost assessment issue are in keeping with the above.
Three measures have been incorporated into the issue to assist in meeting the above aims:
• Adoption of the ‘triple metric’ approach – this calculation methodology is used to calculate the Home Energy Performance Ratio (HEPR). This ensures a balanced approach when considering the fabric performance, systems efficiency and CO2 emissions of the home.
• Introduction of a cost output – this will allow consumers to compare predicted regulated energy costs and identify specified systems that may perform well environmentally, but be more costly to run.
• Introduction of rigour routes – this enables recognition of measures taken to improve the accuracy of the energy calculations.
This guidance document looks into the detail of the calculation methodologies for each of the above three measures. In particular it looks into:
• The HQM energy calculation engine – the basis of the engine which is used to calculate credits regarding energy performance (and high temperature – see other guidance note), and information on how it works.
• Bolt-on calculations – several new elements have been added to the Building Research Establishment Domestic Energy Model (BREDEM1
) methodology to improve the accuracy of the calculations; the required inputs and methodologies for each of these ‘bolt-on’ calculations are discussed in more detail
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