A well-designed underfloor heating system can contribute significantly to the creation of sustainable indoor climate comfort, provided it’s carefully planned first. Julian Clegg, Myson’s UK Technical Manager for underfloor heating, talks through planning an optimally functioning underfloor heating system.
New v Existing buildings
“First, it’s important to note that there is a difference between underfloor heating calculations for a new building compared to an existing building. In the latter case, you can simply calculate the ideal system temperature and values for the hydronic balancing of the underfloor heating system – an estimate based on the year of construction will usually suffice. For new buildings, regulations stipulate that you need more detailed calculations to meet current regulations and NHBC and CIBSE guidance.”
“A proper calculation is absolutely essential for the optimal functioning of underfloor heating in a new building. Buildings today are much better insulated so they have a lower heat demand. This means you can heat rooms more easily, but you can also quickly overheat them if the underfloor heating system isn’t balanced. This is detrimental to both indoor climate comfort and energy consumption”, says Julian.
Essential requirements
A detailed calculation requires at least the following elements to properly design and plan the underfloor heating system:
– A heat load calculation in accordance with DIN EN 12831. This is building-specific, so a detailed floor plan is required with a cross-section of the building, U-values, floor construction, size/type of windows, etc.
– Which type of heat generator will be installed? – as this affects the system temperatures of the underfloor heating system and therefore impacts its design.
Which fixing system is right for the building?
Fixing systems are available to cover almost every application, and it is important to define the requirements for the underfloor heating system at the earliest possible stage. Factors to consider are:
– Is it a new building with sufficient installation height? Or a renovation project where every millimetre counts?
– What screed will be laid?
– What heating capacity (and therefore amount of water) is required?
– What type of pipe is required?
– How quickly should the system react?
– What is the desired room temperature?
– What floor covering will subsequently be installed?
“Based on these values and specifications, you can determine the building’s heat load”, Julian continues. “This can then be used to calculate and design the underfloor heating system and determine the installation distance of the pipes, the position of the heating circuits, length of the heating circuits, etc. Data required for smooth operation of the system, such as pressure losses, water quantities, settings, etc, can then be taken from this layout. More accurate data and specifications means more precise results, leading to more efficient set up and operation of the system.”
Underfloor heating design support
“At Myson, we know from experience that all these calculations take time and require detailed product knowledge”, says Julian. “We can support customers with our internal design and calculation service. Our experts can help in every step of the process, from a preliminary calculation for price and bill of materials to a detailed calculation with all the values for correct hydronic balancing. Every project gets the support it needs.”
