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EKG-f

The National Statistics Bureau published a report (SCB 2009) that stated that the average multifamily building in Sweden used 154 kWh/(m2 year) during the years 2006 and 2007 (the value is not normalized to weather). The corresponding value for Gavleborg indicate 164 kWh/(m2 year). These statistics triggered the EKG-f project which actually was not focused on why the statistics looked this way; it was more-so about what to do about it in view of Sweden’s national goals. EKG-f was a regional project (Akander et al. 2012) aimed to:

  • • Increase the region’s knowledge on the thermal performance of the multifamily building stock and which measures are economical in energy-efficient retrofitting.
  • • Spread information on best practice and good examples to meet forthcoming national targets on reducing energy use and CO2-eq emissions.
  • • Investigate the region’s potentials of reducing energy use in buildings with 50 % and CO2-eq by 75 % without jeopardizing indoor climate.

The strategy was to choose at least one real multifamily building in each of the ten municipalities and use these buildings to explore the energy savings obtained

Map of Sweden with solar radiation (Hydrological Institute 2014) and the region marked in blue

Fig. 8.1 Map of Sweden with solar radiation (Hydrological Institute 2014) and the region marked in blue

from various retrofitting alternatives by means of building energy simulations (BES). Cost estimates of the retrofitting alternatives were assessed and the profitability was evaluated using life cycle cost analysis (LCC). A major part was to investigate if deep energy retrofitting is economical, i.e., if the energy savings would in the long run compensate investment costs and to what extent it would do so.

The studied buildings and main features are listed, in Table 8.1. A requirement was that the building owners intend to retrofit in the near future. The buildings are not statistically representative for the population in any way. These are more-so chosen to have a variation in building types, systems, location, and other characteristics, having in common the aspect of needing renovation to some extent. However,

No

Municipality, town—address, ownership (site location)

Year

Area [m2], Apts [no.]

Load-bearing structure, mean [/-value [W/(m2 K)]

Vent-sys

Heat sys.

Efficiency

[-]

Energy use [kWh/т2 year]

Total

DHW

Facil. El.

1

Ljusdal—Ringvagen 18. private (urban)

1962

721.7

Aerated concrete. 0.794

Nat

DH

0.95

181

32

18

2

Hudiksvall, Delsbo—Smedjeg. 4. municipal (urban)

1970

1221. 10

Wood/concrete. 0.780

Nat

DH

0.95

138

28

1

3

Sandviken—Polhemsg. 9. Co-op (urban)

1950

1378. 18

Aerated concrete. 0.830

Nat

DH

0.95

176

28

5

4

Gavle, Satra—Ulvsatersg. 14. private (urban)

1973

2581. 27

Aerated concrete. 0.708

Exh

DH

0.95

119

30

2

5

Gavle. City—Staketgatan 9. Co-op (urban)

1899

3000.24

Brick. 0.790

Exh

DH

0.95

123

22

9

6

Bollnas, Segersta—Stora v. 33. private (rural)

1955

589. 6

Aerated concrete. 0.776

Nat

Pellet boiler

0.90

162

27

12

7

Soderhamn, Ljusne—Bruksg. 6. private (rural)

1950

607. 8

Timber frame. 0.823

Nat

Pellet boiler

0.85

183

26

12

8

Hudiksvall. Hallstaasv. 40. private (rural)

1880

402. 5

Wood frame. 0.571

Exh

Oil boiler

0.81

213

30

17

9

Sandviken. Gastr. H-by—Allen 5. private (rural)

1966

190.4

Aerated concrete. 0.830

Nat

GSHP

2.8

88

42

4

10

Nordanstig. Ilsbo-Backen 17. municipal (rural)

1971

292.4

Wood frame. 0.456

Nat

Electr.

1.00

171

24

0

11

Ockelbo—Marstrandsv. 68. municipal (rural)

1977

364. 5

Wood frame. 0.631

Exh

Electr.

1.00

195

36

0

Area is the heated floor area, and Apts denote the number of apartments. The presented energy use (total) does not include household electricity. The mean [/-value of the building includes thermal bridges. (Nat natural. Exh exhaust. GSHP ground source heat pump. DH district heating.) The buildings are listed in the order of heat source and with increasing floor area note that all buildings are quite small in size and amount of apartments. The reason is due to that cities and towns in the region are relatively small and quite many buildings are situated in rural context.

The metrics for energy use in Sweden is to divide the annual value by the floor area of spaces which are heated to at least 10 °C. The so-called specific energy use is defined as the sum of energy for space heating and cooling, heating of DHW and facility electricity (i.e., energy for operating the building, such as electricity for fans, pumps, and lighting in common spaces) divided by the floor area. The values shown in Table 8.1 are weather-normalized specific energy use based on bills supplied by the owners. For privacy reasons, household electricity was not investigated and was set in calculations with a default value of 30 kWh/(m2 year) (SVEBY 2009). Notably, household electricity is not included in the definition of specific energy use according to Swedish building regulations.

Aim and Scope

This chapter presents some of the findings from the EKG-f project in terms of what is profitable for property owners when improving the energy efficiency of a multifamily building during renovation. The study investigates whether or not the investment cost of retrofitting alternatives can be recovered on basis of energy savings to avoid increases in rent—especially in view of the housing situation in the region. Focus is primarily on thermal energy savings but issues on indoor climate and building regulation enforcement are considered. Based on the findings, a concluding discussion is made on whether or not some myths on energy use and retrofitting are true.

 
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