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    • ap5 Discrete time dynamical models have a large

    2018-11-14

    Discrete-time dynamical models have a large potential for use on automated and standardized measurements. ARMAX (Autoregressive Moving Average with eXogeneous inputs) models are a wide class of dynamical linear models. Norlén (1990) implements a recursive algorithm to estimate the UA-value of a test cell with ARMAX models, and in Jiménez et al. (2008a) ARMAX models are used on data from a test wall. More detailed information about the heat dynamics of a building can be achieved by applying continuous-time models such as graybox models to data of higher resolution. This has been done for a part of a highly insulated building in Madsen and Holst (1995). In Andersen et al. (2000) it was applied on a multi-room building, and Bacher and Madsen (2011) present a method for a consistent model selection procedure. In 2005, a low-energy house was inaugurated in Sisimiut, Greenland. The objective was to build a house with very low ap5 consumption for heating, which should inspire the development of energy-efficient housing in Greenland and demonstrate the potentials for energy efficiency in a house which should also be a leading example of good indoor thermal environment. The house and its objective was also to be presented in Norling et al. (2006). Therefore the current paper will only briefly introduce the building and then focus on how well the house has lived up to its performance targets, and which challenges it has incurred. Some preliminary performance results were presented also in Rode et al. (2009), but significant improvements have occurred since then. The statistical analysis will be performed on data from before and after the work was conducted on the building and the results will be compared. This paper presents results of statistical modeling of historical consumption data from the house in order to quantify the alleged improvement of the building envelope. It also describes the new measurement setup, and finally presents suggestions for obtaining more detailed heat dynamic models. The paper is structured in the following way: Section 2 gives a brief presentation of the low-energy house, Section 3 describes a statistical methods for analysis of data before and after the repair work on the building. Section 4 lines out plans for future experiments and analysis, and finally conclusions are given in Section 5.
    Description of the house A target for the house was that the energy consumption for heating and ventilation should be only half of that permitted by the 2006 version of the Greenlandic Building Regulations: 230kWh/m2/yr (Government of Greenland, 2006). Furthermore, considering that the house was planned to have a ventilation system with heat recovery – something that was not assumed for residential dwellings in the building regulations – the target value 80kWh/m2/yr was chosen. Building energy simulations were executed to substantiate that this level of annual energy consumption was possible. The means to reduce the energy consumption in comparison with common Greenlandic houses have been to use extra insulation in floors, exterior walls and the roof. Advanced windows have been used with low energy glazing using normally 3 layers of glass. A solar collector has been installed on the roof for domestic hot water heating. The house has been orientated to exploit the light and its geometry optimizes the daylight absorption. The ventilation system is supplied with a counter-flow heat exchanger that uses the warm exhaust air to preheat the cold inlet air. Sisimiut is the second largest city of Greenland (5500 inhabitants) located on the west coast just 42km north of the Polar Circle. The mean average temperature is around 6°C in summer and around −13°C in the winter months. The number of heating degree days is around 8000K-days (base 19°C). The house is approximately 200m2 and is made as a semi-detached house, where the two living areas are built on each side of the boiler room and an entrance hall. Figure 1 shows a picture of the house, and Figure 2 shows the cross section and floor plan. One of the two dwellings serves as home for a family, while the other is used as a guest house for visitors and for research experiments.