LCC analysis of energy interventions in 18 reference buildings

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Description and context

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.

Activities and process

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.

Results and output

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.

The study can be downloaded at: