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Representative averages or generally applicable key figures on costs and benefits are a great help when discussing the feasibility of deep renovations. In the early phase of considering improvements in an existing building, the decision makers involved often have no idea of the required investment and the returns that can be expected. Measurements with the lowest investment costs than often look sensible and the financially and otherwise optimal measurements are not taken into account. While approximations, fairly reliable figures can be provided when tied to a particular building type. For example, all apartments of a particular kind and age tend to cost about the same to insulate to levels 1, 2 or …6, and this will generally produce savings in energy bills of about 1*, 2* or …6*. Figures like these can greatly facilitate the choice between these levels of renovation. The Dutch governmental agency for the (construction) industry RVO has produced studies on the energy needs of representative buildings for some time. These were calculations based on the national Dutch calculation programme that does not provide reliable results for very well insulated buildings. Moreover, their studies report on only one possible renovation package per building type. Looking from the PassREg-perspective this particular package is sub-optimal (providing rather limited savings due to poor insulation) and the study does not indicate the potentials of the optimal energy saving retrofit approach.
Within the PassREg project the RVO study of 2011 was re-calculated, especially including measurements that lead to low energy buildings, passive houses or nearly zero energy buildings. The financial expert H. Wegkamp (of Dantuma&Wegkamp b.v.) calculated 6 alternative interventions for each of 18 reference buildings. To compute the energy performance he used PHPP software version 8.6. Account was taken of energy need based on observed consumption before and after example renovations, as well as of investment costs and their returns in reduced bills according to a Total Cost of Ownership approach. A presentation on these interventions as well as their financial consequences was prepared.
Outcome of this re-calculation is the juxtaposition on physical, energy and financial indicators of 6 possible interventions in the 18 reference buildings. It will enable stakeholders in the Netherlands to base their decisions not on a gut feeling but on reliable figures. The conviction that conserving energy is more sustainable and cheaper by providing insulation than by providing interior climate systems is often heard in PassREg circles. Calculations based on up to date key figures support this notion for many types of housing and provide a convincing argument for the wide deployment of deep renovation. There are some building types, however, for which the more effective renovation today combines rudimentary insulation with a somewhat elaborate mechanical climate control system. This might change with the advent of factory (i.e. cheaper) production of insulation packages. So, the key figures per housing type and age category in the Netherlands have to be updated regularly as the Dutch construction industry is in transition.
From the publication “Voorbeeldwoningen 2011” of Agentschap.NL, we have made an Energetic and Economic analyses of the 18 most common houses in The Netherlands. We started from the situation as described in this publication. Over the years, many of these houses have already been renovated or modernised. All of the houses that we analysed have been built between 1946 and 2005. The following housing types have been analysed:
Energy consumption of the houses is based on actual use. The houses are entered into the PHPP in the current situation. The airtightness is adapted to the technical practice of the period in which the houses were build. Average indoor temperature is set between 16°C and 19°C. For thermal bridges, assumptions are made that match the building style and building period of the houses. The analysis on the investments is based on the energy prices, interest rates and inflation rates, and expected rises: Natural gas € 0.07 kWh Annual rise 4% per year Electricity € 0.22 kWh Annual rise 3% per year Mortgage rent 3% per year Inflation rate 1% per year Lowest housing costs An investment analyses of all the housing types is made in order to determine the lowest housing costs. These housing costs are related to the municipality and is determined by
Also taken into account in determining the return on investment are:
The increase of the market value of the house as a result of the investments, is set on 60%. 40% of the investment vaporizes. In order to be able to compare the retrophit measurements, a fixed amount for Real Estate Tax (OZB), which differs from one municipality to the other, is set for all reference houses.
In the analysis, for each house, the potential improvement measures are calculated for:
The potential improvement measures are investigated: Insulation value of the basement floors Insulation value of the facades, Insulation value of the rooftops, Thermal bridge interrupters in perimeter Window frames, Glass, Set frames, Air thightness, Ventilation system, Co2 regulators, Natural gas central heating system, Geothermal ducts, Geothermal exchangers Bio heaters , Air/water heat pumps, Water/water heat pumps, Hybrid natural gas heaters with ventilation heat pumps, Thermodynamic heat pumps, Solar collectors, Heat exchangers in showers, Photovoltaic cells, Electricity storage systems. Only if the investments mentioned above, proved to be profitable, they are described in the report. Non-profitable investments are not described. Application of measurements The applied measurements always meet the requirements for a healthy and comfortable house. This is a strict requirement that is not compromised.
In the overview below, the TCO for the retrophit and the maximal savings are listed.
|Detached house, built before 1965||320.945,00||-115.151,00|
|Detached house, built 1965 - 1974||295.198,00||-83.396,00|
|Detached house, built 1975 - 1991||246.391,00||-63.261,00|
|Detached house, built 1992-2005||225.691,00||-44.710,00|
|Semi-detached house, built before 1965||273.362,00||-71.263,00|
|Semi-detached house, built 1965-1974||259.488,00||-56.217,00|
|Semi-detached house, built 1975-1991||222.105,00||-23.422,00|
|Semi-detached house, built 1992-2005||211.792,00||-33.019,00|
|Terraced house (middle), built before 1945||269.670,00||-79.335,00|
|Terraced house (middle), built 1946-1964||233.339,00||-51.951,00|
|Terraced house (middle), built 1965-1974||226.138,00||-36.620,00|
|Terraced house (middle), built 1975-1991||211.830,00||-33.921,00|
|Terraced house (middle), built 1992-2005||198.194,00||-22.318,00|
|Maisonnette, built before 1965||343.021,00||-85.227,00|
|Gallery flat, built before 1964||184.475,00||-26.425,00|
|Portico flat, built before 1946||204.110,00||-30.323,00|
Appendix Brochure Examplary houses 2011 - existing housing: reference houses are described and depicted with their characteristics. Accessible via this link: http://www.rvo.nl/sites/default/files/bijlagen/4.%20Brochure%20Voorbeeldwoningen%202011%20bestaande%20bouw.pdf
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