PAS 3652:2026

You can download a DRM-free copy of this standard here.

What is PAS 3652:2026 Household heat batteries – Performance characteristics – Method for measurement about? 

PAS 3652:2026 sets out a method for manufacturers and test houses to accurately and consistently measure the performance of household heat batteries for central heating and hot water.  

The provision of this framework supports the wider shift from gas to electric heating systems.  

The standard supports maintaining technical consistency and aligns performance measurement with existing standards for thermal storage – such as those established for storage heaters and hot water cylinders – while adjusting procedures to reflect central heat distribution and a fixed storage medium. 

The result is consistent, comparable performance data, giving industry players confidence that the capacity, heat loss and heat output of a heat battery have been measured accurately. 

Who is PAS 3652:2026 Household heat batteries – Performance characteristics – Method for measurement for? 

PAS 3652 is primarily intended for manufacturers and test houses, giving them a shared method for measuring and reporting product performance. However, the standard may also be of interest to installers, specifiers and other stakeholders as it is intended to specify performance characteristics that are likely to be considered by those purchasing or recommending heat batteries. 

In this sense, PAS 3652 supports: 

• Heat battery manufacturers: helping align products against consistent performance criteria. 
• Test houses: who are among the main users of the standard’s method for performance measurement. 

It might also be of interest to: 

• Installers and specifiers: who can use performance data to guide system design and product recommendations. 

What does ‘Household heat batteries – Performance characteristics – Method for measurement’ cover? 

This PAS describes a method for measuring the performance characteristics of household heat batteries for central heating and/or hot water. 

This PAS covers household heat batteries that:  

1. are for regular charge/discharge operation, supplying central heating via a central heating system and/or domestic hot water (DHW); 
2. are directly or indirectly charged; 
3. store thermal energy as sensible heat or latent heat; and 
4. have a heat retention of at least 45%.
   NOTE This is when measured in accordance with clause 8.1

This PAS does not cover: 

1. measurements of the safety performance of electrical appliances conforming to BS EN IEC 60335-1; 
2. measurements of the acoustical performance of fan heaters conforming to BS EN IEC 60704-2-2;  
3. the performance of heating appliances used to charge an indirect heat battery, such as a heat pump or electric boiler; and 
4. thermal energy storage systems intended primarily for long-term seasonal or inter-seasonal storage. 
   

Why should you use PAS 3652:2026 Household heat batteries – Performance characteristics – Method for measurement? 

The decarbonization of domestic heating is a critical part of the UK’s transition to net zero, and the electrification of heat requires a diverse range of technologies to suit the varied nature of the UK’s housing stock. 

Household heat batteries can support this shift by storing thermal energy for later use in central heating and hot water systems, offering an alternative route to electrification. However, comparing products and sizing them correctly for a specific system depends on having consistent, reliable performance data – something the sector has lacked to date. 

By establishing rigorous, standardized testing methods aligned with existing thermal storage standards, PAS 3652 provides the technical foundation the industry needs to more effectively bring heat batteries into the low-carbon heating landscape. 

What has changed?  

PAS 3652:2026 is a new publication.