Guidance Note: Domestic hot water temperatures from instantaneous heat interface units

Andrew Mackay

• Publisher: The Chartered Institution of Building Services Engineers
• Year: 2021
• eBook ISBN: 9781912034925
• Topic: Tecnología e ingeniería
• Subtopic: Construcción e ingeniería arquitectónica

The impact of domestic hot water on energy efficiency is a relatively unexplored subject. Historically, domestic hot water has represented a relatively low percentage of building heat energy demand and has been supplied largely via cheap combustion heat sources.In the context of the climate emergency, and a move to lower carbon building designs, we have seen space heating energy requirements fall significantly. This means that domestic hot water now represents an increasingly significant percentage of total building energy consumption.However, the design requirements for domestic hot water are inconsistently understood and applied, particularly in low volume instantaneous hot water systems. This is exacerbated by disparate sources of guidance providing conflicting advice, in terms of both function and safety. There is a clear opportunity to develop a consistent approach to the design of these systems. This approach should prioritise function and safety, but also support low-carbon building design.This Guidance Note summarises current standards and legislation, clarifies where these are relevant to low volume instantaneous hot water systems and sets out a design approach that addresses all key temperature requirements. It aims to provide clear guidance to support practitioners in the delivery of lower carbon, safer and more reliable domestic hot water.

Table of contents

• 1 Executive summary
• 2 Introduction
• 3 Typical domestic hot water systems
• 4 Summary of current guidance
• 5 Safety requirements for domestic hot water
• 6 User requirements for domestic hot water
• 7 The benefits of lower hot water temperatures
• 8 Conclusions and recommendations
• 9 References