Research results: energy | central heat recovery (WTW)
- Commissie Duurzaam
- 3 feb
- 3 minuten om te lezen
Bijgewerkt op: 4 feb
Summary
In the current ventilation system at Kleiburg, a lot of heat is lost. Students from Hogeschool Utrecht investigated an innovative idea: use the warm air being exhausted from the apartments and, via a heat pump, pre-heat the return water of the district heating network. This would reduce the amount of heat that Vattenfall needs to supply and could lower energy bills. The calculations show that the concept is technically feasible and could yield significant savings, although it has not yet been applied anywhere.
Relevance for Kleiburg phase 1
Our ventilation system runs day and night. That means warm air from inside the apartments is continuously blown outside, and cold air is drawn in. In the current system, heat recovery (WTW) is not used.
Students from Hogeschool Utrecht have studied whether and how the wasted heat could be better utilized by connecting a heat pump to the ventilation system.
How it works
On the roof there are about 10 fans that exhaust the warm ventilation air from the apartments. This warm air (about 21 °C) can be captured and directed via a duct to a heat pump placed on the roof.
The heat pump extracts heat from the air and transfers it to the return water from the district heating network, pre-heating it before Vattenfall reheats it to around 65 °C.
According to the students’ calculations, about 40 % of the energy currently supplied by the heat network could be recovered from the ventilation air. This could lead to significant savings on heating costs.
Heat pump
In the calculations, the students assumed the use of a Rhoss Poker 290 heat pump with the eco-friendly refrigerant propane (R290). This pump can deliver water up to 75 °C, which matches the requirements of Kleiburg' s existing district heating system.
Costs, subsidy and financing
In the spring of 2024, the students provided this cost-benefit overview:
The costs of the heat pump installation and the ductwork do not appear to be fully included in that overview, so the estimated payback period may be somewhat optimistic and will need to be recalculated.
The heat pump is eligible for the ISDE subsidy of € 3 375. This subsidy has been included in the cost–benefit overview.
The WTW installation can also be financed through a loan from the National Warmtefonds. (read all about saving, borrowing and subsidies here).
Marginal notes
The students calculated the energy gain at an outside temperature of 11.5 °C;
They assumed a system with CO2-controlled ventilation, in which half of the air in the building is refreshed every hour;
The heat pump uses additional electricity; therefore, it is recommended to combine the heat pump with solar panels and a CO2-controlled ventilation system , which in turn saves electricity.
To our knowledge, this idea hasn't yet been implemented anywhere. We still need to seek further advice on the feasibility of implementing this idea.
A permit is required for installing the heat pump on the roof. Due to protected cityscapes , a roof structure may not exceed 2 meters in height. The recommended Rhoss Poker 290 is 2.26 meters, but there are plenty of subsidized alternatives under 2 meters with the same specifications.
Read more about Energy?
Do you have any questions, ideas or would you like to share your experiences?
Email us at duurzaamkleiburg1@gmail.com . Together we'll chart a path toward a future-proof Kleiburg.