Sensitivity analysis of heating a typical UK dwelling and implications for retrofit design

Kate Simpson,Jennifer Whyte,Peter Childs

doi:10.1088/1742-6596/2042/1/012148

Abstract

The aim of this research is to quantify the impact of heating set point on space heating energy demand for a typical UK dwelling. Retrofit includes fabric energy efficiency improvements. Energy performance certificates (EPCs) inform the householder of typical savings per measure, but this has previously been found to inaccurately estimate space heating energy demand, leading to errors in 'typical savings' presented to householders. The most sensitive inputs have been found to be temperature set point, followed by fabric efficiency. The BREDEM methodology assumes a temperature of 21°C for nine hours a day, rather than ~16°C and ~20°C found in research. The methods used to inform this study are local sensitivity analysis of the domestic energy model, based on a typical dwelling example with calibrated inputs. This is done using an open calibrated Python model, based on BREDEM. The impact of heating patterns on space heating energy demand are modelled pre retrofit; according to differing heating set points, following wall and loft fabric upgrade and full fabric upgrade. The BREDEM heating set point assumptions lead to space heating energy demand predicted ~50-100 kWh/m2/yr higher than real heating set points. Implications for retrofit design and EPCs are discussed.

Highlights

Energy use in households accounts for around a quarter of all energy used in the EU (European Environment Agency 2019)
The work presented in this paper is based on calibrated modelled results using a Python package of the Standard Assessment Procedure (SAP) 2012 (Firth 2021)
The results within this paper show a large range of space heating energy demand between heating set points from ~100 kWh/m2/yr prior to fabric upgrade to ~60 kWh/m2/yr for a partial upgrade and ~35 kWh/m2/yr for a full fabric upgrade

Summary

Introduction

Energy use in households accounts for around a quarter of all energy used in the EU (European Environment Agency 2019). Heat is the largest energy end-use and only 10% is produced from renewable energy Reducing heat loss by improving building fabric performance is critical for both existing and new buildings if we are to achieve carbon neutral cities (IEA 2020), especially as reducing fabric heat loss reduces the demand for heat provision. Many existing buildings were built prior to current standards and encompass embodied energy and aesthetic appeal. There is need for retrofit of existing homes to ensure they are climate resilient, healthy to occupy and fit for the future, while reducing energy demand and reliance on fossil-fuel energy sources Retrofit measures can include building fabric and heat interventions to upgrade existing technologies and these are found to have an attributable impact on space heating related energy demand (Hamilton, Summerfield et al 2016, Shah, Wilson et al 2018)

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