Understanding the data requirements for underfloor heating design and calculation

Underfloor heating calculations for New v. Existing buildings

First of all, 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, if necessary, just calculate the ideal system temperature and values for the hydronic balancing of the underfloor heating system. In that case an estimate based on the year of construction usually also suffices. For new buildings, however, 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 an underfloor heating system in a new building. Because buildings today are much better insulated, they have a lower heat demand. This means you can heat the rooms more easily, but on the other hand 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 Clegg, Technical Manager for Underfloor Heating at Myson.

Essential requirements for underfloor heating calculations

In case of a detailed calculation, the following elements are at least required to properly design and plan the underfloor heating system:

• A heat load calculation in accordance with DIN EN 12831: as this is building-specific, you’ll need a detailed floor plan, a cross-section of the building, U-values of the exterior components and information about the floor construction, as well as the size and type of the windows.

• A decision on the type of heat generator that will be installed. This affects the system temperatures of the underfloor heating system, and therefore its design.

• A decision on the right underfloor heating system for the building. There are different UFH systems in our range to cover almost every application. It’s therefore important to define the requirements for the underfloor heating system at the earliest possible stage. Factors to take into account are:

- Is it a new building with sufficient installation height or a renovation project where every millimeter counts?

- What type of 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?

- Which floor covering will be installed? Each floor covering has its own features, which should be taken into account when designing the system.

Based on all these values and specifications, you can first determine the building’s heat load. This can then be used for the calculation and design of the underfloor heating system, where the installation distance of the heating pipes, the position of the heating circuits, the length of the heating circuits, etc. are determined. All the data required for smooth operation of the system, such as pressure losses, water quantities, settings, etc., can then be taken from this layout. The more precise the data and specifications for such a calculation are, the more precise the results will be and the more (energy-)efficient such a system can be set up and operated.

Underfloor heating design support

“We know from experience that all these calculations take time and require detailed product knowledge”, says Julian. “To support our customers, we therefore offer a heating design and calculation service. Our internal experts help you in every step of the process, ranging from a preliminary calculation for the price offer and a bill of materials to a detailed calculation to get all the values for correct hydronic balancing. Every project gets the support it needs. For example, in case of rooms with a very high heat demand, our specialists can help you determine if the underfloor heating system delivers sufficient power, or if additional radiators are required.”

Do you also have an upcoming project that requires underfloor heating design and calculations? Don’t hesitate to get in touch for tailored advice and support. We will gladly assist you in any way we can.