Before starting the floor covering work, functional heating in accordance with DIN EN 1264-4/BS EN 1264* is carried out from the 21st day after screed installation to confirm the function of the underfloor heating. The screed is then heated to support the drying process. The screed is heated until it is ready for covering. This heating process takes at least 26 days and is absolutely essential for the progress of the construction process in preparation for the floor covering work. The costs incurred by district heating, heat pumps or external heating sources are hidden costs that are not usually calculated. With an external electricity-powered heating source, costs of up to 40 euros per m² can be incurred for the heating phase of 26 days. This means a doubling of the calculated screed costs. The solution to reduce these costs is the shortened heating phase of Retanol® screed, which means that the heating phase can be reduced to up to four days. This saves you more than 5 euros/m² with district heating and up to 33 euros with an electricity-powered external heating source. In most cases, the reduction in heating costs is greater than the investment in Retanol®. This means that Retanol® reduces your construction costs compared to a zero screed.

*UK only

*per m² and day **per m² Assumption: oil consumption 0.3l*, electricity consumption external heating source 2.9 kWh*, electricity consumption heat pump 1.56 kWh*, district heating 1.56 kWh*, oil: 2 €/l and 2.92 kg CO₂/l, electricity: 0.4 €/kWh and 0.42 kg CO₂/kWh, district heating: 0.15 €/kWh and 0.19 kg CO₂/kWh

With average costs per kWh of 15 cents, district heating is the cheapest heat source for heating the screed. However, approx. 6.24 euros/m² are spent over the 26 days, as the heating phase runs at full load. If this seems like a lot, it is helpful to consider the full utilisation hours of a district heating connection. Full utilisation hours are calculated by dividing the total annual consumption in kWh by the connected load in kW. As a rule, this results in 1,300 hours or 55 days. So if 55 days under full load result in an average of approx. 13-14 euros/m², it stands to reason that 26 days (functional and occupancy heating) will result in approx. half the costs.

The heat pump is effective during normal use, as it only generates 25 per cent from the power grid with a COP value of approx. four. During functional and occupancy heating, the heat pump runs at maximum flow temperature, which usually results in a COP value of approx. 1.5. This means that approx. 75 per cent comes from the electricity grid. As a result, the heat pump is cost-intensive at approx. 12.22 euros/m² when it comes to heating with a covering. In addition, many manufacturers do not allow a heat-up phase under full load at the start of heat pump use, as this would invalidate the warranty. The only alternative is to heat up with an external heat source.

Heating with an external heat source is the most expensive. Oil-powered external heating sources are cheaper than electricity-powered external heating sources, as the conversion of electrical energy into thermal energy is less efficient. However, oil-fuelled appliances can only be used from a certain number of m². The 40 kW machine (electricity-powered) can heat up to 330 m² at 100 per cent full load. This means that an oil-powered external heating source with an output of e.g. 70 kW is only worthwhile in the area > 330 m². Overall, however, heating with an external heating source remains the most expensive alternative compared to district heating or a heat pump.