In the Netherlands, a main target of the energy policy is to disconnect 1.5 million houses from the gas grid to 2030. A part of this is the concept “Zero on the meter”, referring to net-zero energy use. This often includes both deep renovation and exchange of the energy system and may be carried out in several ways. Below are three examples, representing different challenges and solutions.
The first example describes a situation where 48 flats went through a thorough renovation, including installation of individual air-to-water heat pumps. One main challenge was the placing of both the indoors and outdoors units of the heat pumps, as well as of the storage tanks. There was simply not a lot of room for the equipment. Part of the solution was to install a compact-built yet service-friendly indoor system, not using more floor space than the replaced gas boiler. The outdoor units were mounted in sets of three, one for each column of flats, and placed inside a casing. The entire renovation also included installation of solar panels on the roofs and prefabricated new facades with added insulation.
The second example shows 12 apartments where four ground-source heat pumps are installed. They provide space heating, cooling and domestic hot water. Each individual apartment is equipped with a 150 litres storage tank. For improved insulation, the building is covered with a “second skin”. This is a lightweight construction that is easily connected to the façade of an existing building. The skin also contains most installation components, saving indoors space. Also, solar panels are placed on the roof and new windows with three layers are installed. The entire renovation work was focused on finding an optimal balance between sustainable renovation, living comfort and affordability – both for the tenant and the housing corporation.
In the third example, 70 terraced houses were insulated and equipped with an energy module. It contains an air source heat pump, a storage tank and a ventilation box, and was installed at the back of the houses in a casing optimized to reduce noise. The energy module was an ‘install-ready’ plug & play unit which can easily be connected at the renovation site. But the first step in the project was to attach insulation panels to the existing facades. This also included three-layer windows. Solar panels were installed on the roof, and the floor was insulated from beneath.
The overall results of the ‘Zero on the meter’ projects are promising. Investigation by the Dutch Housing Research Centre (Centrum voor Woononderzoek) shows that about 80 percent of the residents in surveyed projects are satisfied with the result of the sustainable transformation of their house or apartment.
Bas Roestenberg, The Netherlands (editor of Warmtepompen)