Architectural Layout

The preliminary information related to the typical study building was taken from the NH report as shown in Table 3.1. The building area is 1000 m² divided into five floors (each floor contains three apartments, with an area of 67 m² each) and the total floor area is 221 m², including stairs and lobby [12].

The ceiling height is 2.6 m, matching the average building height for old buildings [17]. In the Miljonprogram 85 % of the dwellings built in multi-story are Lamellhus with a flat roof, therefore roof for this model was defined as a flat type [18].

The window to wall ratio is 25 % placed in all directions, where the architectural layout was designed as per point block model Figure 3.2 [19] and created in IDA ICE as per Figure 3.3.

Define the

Table 3.1 Prerequisite data for Nils Holgersson typical multi-family building [12].

NH Building Value Description

Area 1000 m²

Number of apartments 15 (67 m² each)

Facility electricity (35 A) 15 000 kWh

-Light and equipment related to facility such as the lighting of stair, pumps for heating, fans for ventilation system

Household electricity (16 A) 34 000 kWh

-It includes all electricity related to house living including the light, and equipment such as TV, refrigerator washing machine, drier

District heating 193 000 kWh

Water and sewer 2000 m³

Figure 3.2 Different types of multi-dwelling buildings (the orange represents the common area /staircase [19] with permission from (Maria Wall).

Figure 3.3 Base model of NH building.

Furthermore, to complete the base model, all necessary parameters, for instance, building envelope, infiltration, and thermal bridge, were defined in IDA ICE (refer to Tables 3.2 and 3.3).

Table 3.2 General input data for the NH building.

Inputs Value Justification /Description

Heating set point 21 ℃

No cooling; in Borlänge, the

summers are comfortable and partly cloudy and the winters are freezing, the average temperature varies from -6 ℃ to 17 ℃ (refer to Appendix 1).

Wind profile City center

Thermal bridge Poor Considered poor because of the high heating demand

Infiltration 6 ACH

-As per EN134765 for leakage study based on construction year

-Pressure coefficient defined as the building sheltered

Domestic hot water 25 kWh/(m². year) [20]

Ventilation 0.5 L/s.m² Exhaust ventilation system

Table 3.3 Building envelope for the NH building.

Surface Type Material Value

W/(m².K) Justification

External wall Rendered light

weight 0.53

-Lightweight concrete is common in the old multi-family in non-metropolitan area such as Borlänge [19]

- In Boverket the U-value defined as 0.56 W/(m²K) for the buildings constructed before 1960 [2]

Roof Concrete joist

roof (flat roof) 0.172

- The default in IDA ICE

- Refer to Boverket the U-value is 0.2 W/(m²K) for the building constructed between 1960 -1975 [2]

- 85 % of the dwellings built in multi-story buildings during the Miljonprogram are Lamellhus type which has a flat roof [18]

Floor Rendered

concrete 2.9 -The default in IDA ICE Windows Double clear air

g = 0.71 Glazing 2.86 Frame 1.5

-The default in IDA ICE

-Refer to Boverket the U-value is 2.2 W/(m²K) for the building

In the base model ventilation rate is considered 0.5 L/s which is higher than BBR. According to a study that included a measurement for a building constructed in 1960 in Linköping showed 0.82 ACH, which is 0.5 L/s per m² [21]. Moreover, multi-family houses between 1961 and 1983 had higher average ventilation rates than other types, and it was 1.44 m³/hr per m² [22].

The ventilation system for buildings constructed in the 1970s in Sweden is the exhaust ventilation, where the fresh air intakes through cracks and gaps in facade [23].

Another critical input that affects the results significantly is the internal gain which includes occupancy, lighting, and equipment in IDA ICE; those values defined as per Table 3.4

Table 3.4 Internal gain for NH building.

Internal gain source Value Description

Occupancy 0.034 person/m²

-Apartment of 3 rooms [20]

Appendix 2.

-From Swedish Tenant association 2018 [22]

Lighting 3 W/m² Swedish Energy Agency*

Equipment (household) 11 W/m² Swedish Energy Agency*

Equipment (Facility)

*According to the Swedish Energy Agency, the household measurement for the 400 homes project showed consumption of 3000 kWh/year for apartments. It is divided into lighting, and household equipment, whereas the share of equipment, is 2370 kWh and 3.7 times higher than the lighting share, which is 630 kWh (refer to Table 9) [20]. Based on that ratio, both lighting, and equipment assumed and input in IDA ICE with several simulations resulted with 3 W/m² for lighting and 11 W/m² for equipment, to achieve the target of NH report which is 34 000 kWh for tenant consumption.

In reality, it is not relevant for reasonable energy consumption to calculate a full load of internal gain, and that is why IDA ICE considers 60 % of internal gain in energy simulation [16].

According to the NH report, the annual facility load is 15 000 kWh, and to match this Figure, several assumptions and simulations were performed. Where laundry, pumps, and elevator assumed as parts of that load. In this study, the occupancy schedule is based on Sveby's 2012 recommendation which is 14 hours per day when people present at home [20]. Usually from 17:00 to 7:00 (assuming that individual gets up at 6 AM and leaves the house at home 7 AM then return at 5 PM). That schedule used an input for the base model in IDA ICE (refer to Figure 3.4).

Figure 3.4 Occupancy schedule for NH building.

For lighting and equipment, it is hard to predict the inhabitant’s behavior. The assumption of those schedules referred to an extensive time survey which combined measurement and modeling behavior data [25] (see Appendix 3). That approach of schedules adopted as input for the base model in IDA ICE (refer to Figures 3.4 and 3.5).

Figure 3.5 Equipment schedule for NH building.

Figure 3.6 Lighting schedule for NH building.