Commissioning-Oriented Building Loads Calculations. Application to the CA-MET Building in Namur (Belgium)

Abstract

The parallel use of whole building simulation and monitoring of building energy consumptions (heating, cooling, lighting and other electricity consumptions) represents a potential “high-level” commissioning tool in order to verify, either as a one shot campaign or as a continuous process, the correct operation of a building. The most advanced approaches use on-line building simulation to continously compare the real performance of the building to a base line provided by simulation. In that context, different levels of building loads calculation can be used, ranging from rough methods like eg degree day methods to detailed multizone building simulation. The former methods use aggregated information about the buildings (“global” parameters like the heat loss coefficient for instance) and provide as outputs average quantities (energy consumption for a given average controlled temperature) while the latter require a high number of parameters and deliver very detailed results (hourly evolution of demands in each zone of the building). A major question concerns the suitability of the different approaches in a commissioning context. This papers illustrates the use of different calculation methods (heating and cooling loads) for the particular case of an office building located in Namur (Belgium), which is the object of an intensive re-commissioning activity for several years. Very global methods are used as well as detailed computer simulations using TRNSYS Multizone building types 46 and 56. In the latter case, the model is calibrated using reference periods and can serve as a baseline indicator of the energy consumption in the building. The complexity of the building (300 m long, modular architecture, presence of an atrium-like internal street) required some simplifications in the modelling associated to a specific methodology to extrapolate the results got from the simulation of a relatively small part of the building to the whole picture. The paper will explain the adavantages and disadvantages of each approach, the required information and the limits of the results. The potential use of the different calculation levels for the implementation in a continous commissioning process will be examinated as conclusion of the work.