Mark Krull, Director at LCL Awards, discusses the importance of getting heating design right, as outlines in CIBSE’s new Domestic Heating Design Guide.
The publication of the Future Homes and Buildings Standard (FHBS) in March signalled a turning point in the way news homes must be designed and built. Low carbon heating, solar photovoltaics and battery storage are in, gas boilers are out. Heat pumps, which have been growing in popularity in recent years, particularly in the retrofit sector, will soon become the dominant technology across all property types.
For existing homes, recent uplifts to the Boiler Upgrade Scheme, and the introduction of the Warm Homes Plan are further driving demand for renewables. This is all exciting stuff, but as such requires up to date guidance for system designers and installers of domestic heating systems.
Queue the recently launched CIBSE Heating Design Guide 2026, which sets a benchmark for meeting the requirements of the FHBS. LCL Awards sits on the CIBSE Domestic Building Services Panel (DBSP) alongside 17 other members from across the sector, representing training, technical and regulatory factions of our industry, all of whom of had a hand in ensuring this updated Guide meets the needs of industry now and in the future.
Important updates
Influencing the direction of our own Domestic Heating Design qualification, there are some important updates that will hopefully improve outcomes for both installers and their customers:
Expanded options for designing outdoor temperatures: Moving away from solely focussing on sizing heating systems for the coldest day of the year, in the new guide, designers are given options down to the 95th percentile of winter temperatures, allowing for nuanced decisions. In modern, well-insulated homes (of which all new builds should be), this should lead to more cost-effective solutions for the homeowner.
Expanded heat emitter information: The guide looks beyond standard steel panel radiators, with more detailed information on fluid dynamics, modern hydraulic arrangements, circulator control and low-loss headers. It also covers more advanced layouts, including four-pipe heat generators and manifold distribution.
Transparent design parameters: The newly introduced System Criteria Document is a written record of design decisions, such as heat-loss calculations, flow temperatures and controls. If a system is not performing as it should, this Document can be referred back to, providing transparency for both homeowners and building services professionals.
Linking space and water heating: Domestic hot water guidance has been updated in line with BS EN 12831-3:2017, with new advice on cylinder sizing, storing hot water below 60°C and the related thermal disinfection process.
Fabric first is a must: Updated U-value tables are included, covering the latest construction methods, plus revised guidance on air permeability assessment. In new builds, an air permeability test is always the preferred approached. For retrofit work, SAP 10 methodology provides an alternative.
Focus on heat loss: The 2026 guide places greater emphasis on accurate heat loss assessment, with CIBSE aligning the method more closely with BS EN 12831-1 and incorporating updated weather data covering 28 zones and four outdoor design temperatures.
Getting heat loss calculations right is essential to efficient system design. If they are incorrect, emitter sizing, flow temperatures, plant selection and overall performance can all be affected, resulting in wasted energy, higher bills and dissatisfied householders.
Learners on our domestic heating and hot water system design qualification can partner with Heat Engineer and use their heat loss calculator software free of charge whilst training.
‘Low’ is the new normal
Low temperature design should be central to all heating systems, so meeting CIBSE’s latest guidance is also important for experienced gas installers and those entering the sector. Other useful reading includes CIPHE’s new guide, ‘An Introduction to Low-Temperature Hydronic Heating Systems’, which explains the principles of low-temperature system design and provides practical guidance for designing efficient hydronic heating systems operating at 55°C and below, including 45°C for heat pump installations in new build properties.
While the new build market will soon be ‘fossil fuel free’, gas is still responsible for heating and hot water in the majority of UK homes, many of which will transition to a heat pump over the coming years. Today’s installers need knowledge of the past, present and future, to meet the needs of the UK’s varied housing stock.
Up to date qualifications
Heating system installers need to be up to date with current industry guidance, and as such we have updated our Domestic Heating and Hot Water System Design in Dwellings qualification in-line with the CIBSE Heating Design Guide 2026.
Aimed at existing engineers who may not have previously undertaken formal learning in relation to designing modern heating and hot water systems, the course is also a progression route for learners who wish to undertake the LCL Awards Level 3 Award in Low Temperature Heating and Hot Water Systems in Dwellings.
LCL Awards is currently working with CIBSE and the HPA to develop the ‘Domestic Heat Pump Design & Installation Guide (HPG)’.
