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The world of construction is subject to growing requirements regarding the quality of buildings. The delivery of an envelope must be accompanied by an EPB certificate. In addition, contractors are requiring levels of performance that are higher than those imposed by the regulation: BREEAM, LEED or passive certifications. These certifications are based on theoretical calculations and do not provide a guarantee of real building performance. However contractors aspire to obtain better guarantees regarding buildings real performance. The increase in the number of airtightness tests performed reflects this concern. In 2014, one out of every three new dwellings is subject to air-tightness measures in the Flemish Region and one in five in the Walloon Region of Belgium. In that context, there is a growing interest in the concept of ‘energy performance contracting’ defined by the European Directive 2012/27/EU as “a contractual arrangement between the beneficiary and the provider of an energy efficiency improvement measure, verified and monitored during the whole term of the contract, where investments (work, supply or service) in that measure are paid for in relation to a contractually agreed level of energy efficiency improvement or other agreed energy performance criterion, such as financial savings”. Being able to confirm that the obligation of result is achievable and achieved, is the new challenge faced by the construction industry. Research institutes want to consolidate sets of achievable reference values for energy performance indicators and to compare them with theoretical predicted values. They also intend to extend their expertise regarding the analysis of data collected by in situ testing. Education institutions that forms architect engineers intend to promote their training in the processing of data collected through building monitoring, as a significant amount of those engineers are involved in the management of building stocks, thereby confronted to large samples of measured data. Universities are also committed to serve the community. By promoting the quality of workmanship in the construction sector as well as the quality of the building stock, a guarantee of quality is provided to the consumers. New job opportunities could also be created in the measurement of building performances and the analysis of monitored data. In that context, Cambbridge research project is gathering a Belgian construction company (Jacques Delens s.a.) and a university (UCL) in order to develop reliable methods that can be applied on site during the construction phase in order to assess the actual performance of buildings at a moment when it can still be improved to reach the target without entailing over costs. The proposed measurement process includes 5 days of pre monitoring during which the building can be occupied or not, followed by 9 days monitoring without occupancy. It is a tradeoff between the constraints of the construction work, that do not allow too much time to be spend for the tests, and constraints related to building physics. The research implies parallel experiments on identical building units, to check the reliability of a method based the observation of floating indoor temperature compared to a conventional co heating test. The relevancy of the placement of internal insulation on party walls is also checked as it allows the indoor temperature to reach higher values and as it reduces heat losses to neighboring units. As quasi-stationary co-heating has so far been limited to the winter months, it is crucial to expand the time window for HLC assessment by developing summer approaches. Methods based on the observation of floating indoor temperature meet that goal. Such innovative measurements methods try to take advantage of solar gains effects instead of avoiding them. |
