Checklist for a balanced and efficient heating system

Question 1: what kind of building is it?

The first key factor that influences the heating load is the kind of building. Naturally, a detached house has a different heating and cooling demand than a terraced house, an apartment building, or an office building.

Question 2: how is the building used?

Depending on how the building is used, a different heating and cooling system might be required. A family home that is occupied all year round, and maybe even includes a home office, must be heated and controlled differently than a holiday home that’s only used sporadically or an office building which is only occupied from 9 am to 5 pm on weekdays.

Question 3: what is the building used for?

Whether the building is intended for domestic or commercial use also makes a difference in the selection of an efficient heating and cooling system. While heating and cooling solutions for residential buildings are often tailored to the individual living comfort and lifestyle habits of the occupants, systems for commercial use, for example in office buildings or schools, need to create an indoor climate that maintains productivity, concentration and well-being.

Question 4: what is the degree of insulation?

Old buildings with little or no insulation have much higher heating and cooling loads than modern or energy-efficiently renovated buildings. In addition to the system technology, the degree of insulation also influences the type, size and design of the new heat emitters (radiators, panel heating, etc.). 

Question 5: what are the internal loads and gains?

In addition to the external heating and cooling load, i.e. the amount of energy that a building loses via its external surfaces and air exchange, there are also internal loads and gains. This is particularly relevant in well-insulated and energetically balanced buildings (thermos effect). For example, the number of people in a room  affects the heating and cooling load. Each person emits about 80-100 W of power to the room, depending on their activity. In winter, the additional heat gains provide a reduction in the heating load, whereas in summer additional heat gains can be combined with cooling. Electrical appliances also have an important influence on heat gains. To prevent overheating of the rooms due to high energy gains, a fast-acting transfer system for the heat and/or cold with an efficient and intelligent control system is required.

Question 6: Is the system correctly hydraulically balanced?

Another important point for an efficient heating and cooling system is hydraulic balancing. Water always follows the path of least resistance. With hydraulic balancing, one tries to adjust the resistances so that all heating surfaces receive exactly the amount of energy required according to the heating and cooling load. If the heating surfaces are over- or undersupplied, the desired room temperature will also be over- or undershot. Incidentally, the same applies to the correctly set pump characteristic curve and heating curve at the heat and cooling generator.

Question 7: Are the heating surfaces correctly dimensioned?

In addition to the hydraulic balancing, the heating and cooling surfaces must of course also be adapted to the energy requirements of each room. While oversizing a radiator or a surface heating and cooling system can be compensated for by the control system to a certain extent, under sizing results in the room not being heated or cooled sufficiently. In addition to the size of the heating surfaces themselves, the system temperature suitable for the heat and cooling generator is decisive for the power output of the heating and cooling emitters.

Question 8: which energy generator is currently being used?

A decisive criterion for the energy efficiency and sustainability of a heating and cooling system is the harmonious interaction between the energy generator (heat pump, boiler, condensing boiler, etc.) and the energy transfer (radiator, fan convector, surface heating and cooling, etc.). In addition to the appropriate energy source (oil, gas, electricity, etc.), each energy generator has a system temperature at which it works most efficiently. Whereas old low-temperature boilers used to operate at flow temperatures of 70°C and more, condensing boilers should be operated at a maximum of 55°C and heat pumps at a maximum of 35°C to achieve maximum efficiency. There is also a suitable energy transfer system for each system temperature. While, for example, compact radiators or column radiators are particularly suitable for heating with system temperatures above 55°C, fan convectors or surface heating and cooling systems are particularly suitable for heating and/or cooling with temperatures below 35°C.