10.07.2015   BACKGROUND

Example buildings and simulation models

Four models for low-energy buildings are used, which have been calibrated against meas­ured time series of one year length (Gieseler et al., 2003). These buildings shown in Fig. 1 and Fig. 2 represent small to medium sized low-energy buildings of different construction types. They were built between 1995 and 1998 in North-Rhine Westphalia, Germany. The

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outer envelope is described in Table 1, whereas the key con­structional data are given in Ta­ble 2.

Fig. 1: Object 1 (left): The building in Essen — Kraienbruch, Germany, is a three story multi-family house in massive construction with basement.

Object 2 (right): The building in Wenden-Hunsborn, Germany, is a 1A-story single family house in wooden framework construction without basement.

Fig. 2: Object 3 (left): The building in Wenden — Hillmicke, Germany, is a two-family house from pre­built concrete elements with two upper floors and heated basement.

Object 4 (right): The building in Lindlar-Hohkeppel, Germany, is a single family house in wooden con­struction with two upper floors and without basement.

For the simulation of the thermal behaviour of all four buildings, the simulation software TRNSYS, version 14.2, has been used. The major part is a "Type 56" model with 8, 7, 8 and 10 zones for objects 1, 2, 3, and 4, respectively. The code of "Type 56" in our copy of TRNSYS 14.2 has been modi­fied by us to achieve a proper edge correction for the U-value of windows. This modification leads to equivalent results like the window model of TRNSYS 15. The simulations are run with METEONORM weather data (Meteotest 2000). The weather data used for the current analy­sis are for the locations Stock­holm, Trier and Milan. In Table 3, the key characteristics of the weather data are shown, i. e. the heating degree days and the total solar radiation. The simula­tions use a common standard­ised user behaviour. The total internal gains in the period September to May are 32 kWh/m2 for object 1, 28 kWh/m2 for object 2, and 31 kWh/m2 for objects 3 and 4. The small variation is due to different occupancy, following from the details of the floor plans. The minimal infiltration rate is 0.1 ach/h. Additional window ventilation (plus 1 ach/h) and active shading by the user is only included, when the indoor temperature exceeds 24 °C. The resulting heating demand for the buildings under standardised user behaviour and different weather conditions is shown in Table 4. For typical German weather conditions, which can be represented by data for the location Trier, the buildings require heating between about 15 kWh/(m2 a) and 80 kWh/(m2 a). This represents the range from so called "passive houses" to today’s standard (new) buildings.

Table 1: Construction types for the outer envelope of the four objects.

Wall

Roof

Ground floor

Object 1

Limestone with polystyrene outside

Rafter with mineral fibre, polyurethane layer inside

Polyurethane on concrete

Object 2

wooden framework with integrated mineral fibre

Rafter with mineral fibre

Polyurethane on concrete

Object 3

Pre-built reinforced concrete elements with polystyrene outside

same as walls

Polystyrene on concrete

Object 4

Wooden monocoque construction with integrated and outside mineral fibre

same as walls

Polystyrene on concrete

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