Reference buildings based on national building codes 2001

To start, common building geometries for a single family house, row house and apartment building were defined (see Appendix 1). For each country in the three climate regions, the allowable space heating demand and ventilation requirements set in the national building codes of the year 2001 were taken as the targets for the reference buildings. Working backward in an iterative process, the average envelope standards in each climate region were calculated to exactly meet the standards. In this way the regional reference buildings were defined.

Table 7.2.1 compares the average U-values for the different housing types in the three climate regions. The U-values for the cold region are relatively low due to a compensation for not using 50 per cent ventilation heat recovery, which otherwise should have been used for a Swedish reference building. As expected, the insulation standard is much higher in the north than in the south. However, in Figure 7.2.1 it can be seen that this is partially explained by the building codes in the south being less ambitious. The end result is that the space heating demands for all three housing types in the mild climate exceed the demands in the temperate and cold climates! Similarly, the space heating demand of the housing built to the regional codes in the temperate region exceeds the demand in the cold region. In all cases, logically, the space heating demand is lowest for the apartment building and highest for the single family detached house.

The space heating demand was calculated according to EN 832, using the Bilanz program (Heidt, 1999). All reference houses in the three climate regions are assumed to have ventilation losses equivalent to 0.6 air changes per hour (ach). No mechanical ventilation system or ventilation heat recovery is assumed.

The space heating demand is, in general, high for buildings constructed according to the actual building codes of 2001. This means that the potential to radically reduce the demand is high, and is extremely high for the mild climate region.

Table 7.2.1 Mean regional U-values of the building envelope based on national building codes for the year 2001

Building envelope mean U-value (W/m2K)

Cold climate

Temperate climate

Mild climate

Single family house

0.29

0.47

0.74

Row house (six units)

0.33

0.55

0.86

Apartment building

0.35

0.60

0.94

Source: Maria Wall

Figure 7.2.1 Space heating demand for the regional reference buildings with standards based on building codes for the year 2001; the reference climates have been used

7.2.1 Primary energy demand

In standard buildings today the energy use for heating and domestic hot water is mostly provided by fossil fuels (gas and oil), district heating and electricity. An important goal is to reduce the use of nonrenewable energy. Therefore, it is also important to show results in terms of primary energy demand.

Since the focus is to reduce the non-renewable energy use, the primary energy target defined in this book only addresses the non-renewable part of the primary energy demand (see Appendix 2). To judge the different environmental impacts of buildings during operation, two indicators are used in this book:

1 The primary energy, which is the amount of energy use on site, plus losses that occur in the transformation, distribution and extraction of energy.

2 CO2 emissions, which are related to the heat energy use, including the whole chain from extraction to transformation of the energy carrier to heat. Using the CO2 equivalent values, not only CO2 but all greenhouse gases are taken into account, weighted with their impact on global warming.

As a reference and as a base for finding a primary energy target, the non-renewable primary energy demand for the regional reference houses was calculated as follows:

• First, the end energy use, including space heating demand, DWH demand and system losses were summarized. Energy for electrical appliances such as pumps and fans was also summarized. The DHW demand was, in all cases, assumed to be 40 litres per person per day.

• Second, the DHW and space heating demand were multiplied with the primary energy factor 1.1 (representing a 'not unusual' system - for example, oil or gas). When electricity for fans and pumps was assumed as part of the system, the electricity was multiplied with the primary energy factor 2.35 (EU mix + Switzerland + Norway).

Figure 7.2.2 shows an example of the primary energy use when no electricity for fans and pumps is assumed in the reference buildings. All examples are based on oil or gas for heating. The mean regional reference level of year 2001 were around 124 kWh/m2a, varying between 110 and 156 kWh/m2a.

Figure 7.2.2 shows an example of the primary energy use when no electricity for fans and pumps is assumed in the reference buildings. All examples are based on oil or gas for heating. The mean regional reference level of year 2001 were around 124 kWh/m2a, varying between 110 and 156 kWh/m2a.

Note: This includes DHW and space heating demand. No electricity is assumed for fans and pumps. Source: Maria Wall

Figure 7.2.2 Nonrenewable primary energy demand for the regional reference buildings

Note: This includes DHW and space heating demand. No electricity is assumed for fans and pumps. Source: Maria Wall

Figure 7.2.2 Nonrenewable primary energy demand for the regional reference buildings

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