Insulation can be used to bring down the amount of heating we need for our houses while staying comfortable. The ETM allows you to choose insulation levels for each housing type and for all buildings (in the Commercial and Public Services, shortly CaPS, sector) separately. This page discusses the modeling methods used for the implementation of insulation in the ETM and the data that underlies the modeling.

Figure 1: Insulation sliders households

Figure 2: Insulation sliders buildings

Housing types

We have distinguished five housing types for modelling heat demand in households: apartments, corner houses, detached houses, semi-detached houses and terraced houses. These housing types are recognisable in the Netherlands and used in the Basisregistratie Adressen en Gebouwen (BAG), which contains all official data of all households and buildings in the Netherlands.

Figure 3: Number of houses sliders

Heat demand reduction

There are five insulation sliders for each housing type and there is one insulation slider for all buildings in general. The insulation sliders set the heat demand reduction, which is the fraction of heat demand that is saved through insulation. We derive the heat demand reduction from the "Energie-Index" (EI, energy performance index) of the houses and buildings within a region, which is retrieved from BAG-data for the Netherlands. The EI represents the energy performance of the house/buildings: how energy-efficient is it? Unfortunately, the mapping between heat demand reduction and the EI is ambiguous, because the EI does not only depend on the insulation level. Instead it is based on 150 different factors (source: RVO), including the presence of solar panels or the type of heating technology installed, which both do not influence the heat demand of a building. Additionally, the EI is not definitive for many houses yet. Energy labels are the simplified version of the EI.

Despite the above reasoning, we chose to use the EI, because there is no other data available. It still gives a reasonable insight into the average insulation level of a region. This is the mapping that we used to translate the the EI into a heat demand reduction for each housing type relative to the lowest possible energy label G:

Energy labelEnergie-IndexDetachedCornerTerracedSemi-detachedApartement
G> 2.70%0%0%0%0%
F2.41 - 2.74%3%3%4%3%
E2.11 - 2.407%5%5%9%5%
D1.81 - 2.111%13%13%13%8%
C1.41 - 1.817%21%21%18%17%
B1.21 - 1.424%29%29%29%27%
A0.81 - 1.237%35%37%40%32%
A+0.61 - 0.850%42%46%50%38%
A++0.41 - 0.659%55%57%60%52%
A+++< 0.467%69%69%69%67%

For utility buildings we calculated the heat demand reduction relative to a label E building, because there was not sufficient data available for lower energy levels:

Energy labelEnergie-IndexBuildings
E2.11 - 2.400%
D1.81 - 2.131%
C1.41 - 1.846%
B1.21 - 1.454%
A0.81 - 1.264%
A+0.61 - 0.874%

The above tables show a rough estimate of the relationship between energy labels, EI and heat demand reduction. The mapping is based on the following data:

NOTE: the label image above the household insulation sliders shows the average label vs. heat demand reduction mapping for all housing types.

Insulation costs

In the ETM costs are calculated based on the 'greenfield approach', which means that no costs are calculated for the current situation and costs are only added when changes occur. So insulation costs are only taken into account when the insulation in houses is increased. (NOTE: when the user reduces insulation, nothing happens: neither to the costs or to the heat demand. We consider reducing insulation as not realistic)


The insulation costs for houses are based on the Ecofys report 'De systeemkosten van warmte voor woningen (2015)', where the investment costs for different 'insulation jumps' (low -> medium insulation, low -> high insulation, medium -> high insulation) are specified. We have chosen to use the 2020 insulation costs. The table below shows the insulation costs for existing houses.

Figure 4: Insulation costs existing houses

When the number of houses increases for a certain housing type, the newly built insulation costs are taken into account for these newly built houses. If the insulation level of that housing type is not set on "high" insulation, we use interpolated insulation costs. The insulation costs in the table below only include the materials used (so cost of labor are not included).

Figure 5: Insulation costs newly built houses

Low, medium and high insulation in the report is roughly specified as: Figure 6: Insulation levels Ecofys

To link the insulation costs to specific heat demand reductions we used ECN heat demand profiles that have been used for the Ecofys study. These heat demand profiles are available for each housing type and the three insulation levels. We first summed the total heat demand per year for each insulation level and each housing type. Then we calculated the heat demand reduction for each housing type relative to the heat demand of the low insulated house. The calculation resulted in the following mapping between low/medium/high insulation and heat demand reduction:

Housing typeLowMediumHigh
Corner house0%23%69%
Detached house0%23%67%
Semi-detached house0%26%69%
Terraced house0%31%69%

The insulation sliders are continuous and not limited to only three choices (low / medium / high). Therefore, the insulation costs have been interpolated; the resulting .csv-files can be found here.

NOTE: The insulation costs for houses are not a fixed amount per % heat demand reduction, but instead the costs depend on the level of insulation in the present year: e.g. going from 0 to 30% is cheaper than going from 30% to 60% insulation.


The insulation costs for buildings could not be retrieved from the Ecofys study. Instead, the costs originate from the BAG-data used in the Vesta energy model (Vesta Utiliteiten BAG (2016) & Vesta Utiliteiten Nieuwbouw BAG (2016)):

  • In these datasets the insulations costs are given for each insulation jump and each type of utility building. Since the ETM only models an average utility building, a weighted average has been calculated for the insulation costs. We did this based on the Dutch distribution of floor area between the different utility building types (ECN).
  • The datasets report minimum and maximum insulation costs, based on taking the insulation measures on a natural vs. independent moment, respectively. A natural moment would be when several buildings are renovated at once, so insulation would cost less money than when one building is separately insulated on an independent moment. For new buildings we have assumed the insulation costs to be the minimum and for existing buildings we have taken the average of the minimum and maximum costs.

The above assumptions result in the following insulation costs for an average utility building:

TypeInsulation costs [€ / % heat demand reduction]
Existing utility building€ 605.99
New utility buidling€ 478.55

Heat demand profiles

The ETM models heating in households and buildings on an hourly basis in the so-called "Fever" calculation. For this calculation hourly heat demand profiles for houses and buildings are needed.


The housing type and insulation level both have influence on the heat demand profile of a house. High insulated apartments for example have a flatter profile than low insulated detached houses. As we cannot specify heating technologies per housing type in the ETM, one average hourly heat demand profile is constructed for the housing stock in general and used in the Fever calculation.

The households heat demand profiles originated from the ECN heat demand profiles from 1987, which was a year with a very cold winter (link to profiles). These profiles are available for each of the five housing types and low / medium / high insulation. We modified these profiles to fit 2015 with this script, since the 2015 heat demand profiles are not publicly available.

The insulation sliders influence the heat demand profile of that specific housing type; it is interpolated between the low, medium and high insulation heat demand profile. The average heat demand profile for the housing stock in general is than constructed based on the shares of the different housing types. This results in the following heat demand profile (including hot water demand) for the Netherlands when there would be 50% low insulated detached houses and 50% high insulated terraced houses:

Figure 7: Heat demand profile terraced houses


For buildings the heat demand profile was harder to construct, since no public heat demand profiles are available. This is the profile that is used for the time-resolved calculation (link):

Figure 8: Heat demand profile buildings