Today, the five buildings serve as residential buildings containing four apartments each.
Year of construction, representativeness
The five quite similar buildings are constructed in 1937 (see Figure 95). Brick walls and un-insulated roofs give a poor energy performance. The slabs against the cold attic are assumed filled with clay. The windows were re- placed in 1985 (almost 25 years old) and some are punctured. The buildings are mainly naturally ventilated, which means there is no mechanical control of air volumes. In some of the apartments mechanical ventilation has been operating in the kitchen, but the functionality is poor. There is no mechanical ventilation from the bathroom. Heating is based on electricity and wood fuel. Based on a condition survey and a strategic analysis, it is recommended that the building is upgraded to a concept that is close to the Norwegian passive house standard. The functionality of the building is poor, so an extension should be built to house toilets, bathrooms and elevator/stairs. It is not realis- tic to cover the building's electricity needs with energy produced at the build- ing with current technology. This is because the site is not suitable for the use of wind turbines and a solar plant would not be economically viable. Dis- trict heating is recommended as energy supply for Stibolts gate 13. Alterna- tively, electricity may be used if there is a need for a reduction of costs to complete the upgrade.
Figure 95. One of the five residential buildings in the case study. Photo: (Anders-Johan Almås).
Funding models and solutions
The Municipality of Drammen is involved in different national programs, such as “Future built” and “Fremtidens byer”. The participation in these projects can benefit in allocations and funding if the residential buildings is included as a pilot project in these programs. More information about the programs will be presented later in the case report.
Refurbishment topics and coverage
A condition survey has been conducted in order to reveal needs for mainte- nance and replacements (see Table 22). Overall, the state of the building is poor. There is a need for extensive refurbishment and improvement of ener- gy efficiency. Structural building components such as outer and inner brick walls are in relatively good condition, while other components like windows and ventilation systems are in poor condition.
Table 22. Overview of condition survey. Building component Description
Outer walls 35 cm brick, exterior plaster. Plaster damages, need for exterior mainte- nance. Un-insulated walls, large heat loss.
Roof Relatively new roof tiles, wooden structures are in good condition. Good ventilation in attic. Un-insulated roof, large heat loss.
Windows From 1985. Leakages, poor thermal properties. Slabs against attic Slabs are filled with clay. Poor thermal properties. Slabs against cellar Concrete without visible damage. Poor thermal properties.
Ventilation Natural ventilation, no mechanical ventilation from kitchens or bathrooms. Electrical Varies – mostly switch fuses. Automatic fuses in Stibolts gate 9. Heating system Electrical and wood.
The outer walls are brick walls in good condition, but the exterior façade is worn and is ready for upgrading. The insulating properties of brickwork are
191
The buildings are naturally ventilated. A few kitchens have mechanical venti- lation, but with varying function. The electrical system and piping systems are not currently considered in detail.
The measurement of energy consumption in 2007 and 2008 shows large variations in electricity use for the five different buildings. The reasons for this are not known, but the use pattern, number of persons in the household and "energy-saving attitudes" of the residents is of great importance to ener- gy usage. On average, the energy consumption per building is around 60,000 kWh/year. This corresponds to approx. 300 kWh/m2 heated gross floor area per year, which is very high. Today's regulatory requirement for residential buildings is 120 kWh/m2 heated gross floor area per year, i.e. less than half of the measured consumption. Non-insulated building parts, old windows, draught and natural ventilation are the main causes of the high energy use. In addition, several of the apartments are equipped with a wooden stove.
Three different refurbishment concepts are analysed for Stibolts gate 13 as shown in Table 23. The first concept is refurbishing according to the Norwe- gian building code. Concept number two aims to satisfy the Norwegian pas- sive house standard. The final concept examines the possibility of Stibolts gate 13 as a retrofit zero energy building. Simulation of energy demand, heat and moist conditions and calculations of thermal bridges are given for the concepts. In addition, building costs are calculated.
Table 23. Summary of analysis of different renovation concepts. Current state Concept according
to national building code
Passive house con- cept
“Zero energy building” concept
Net heating demand (kWh/m2/year)
287 51 15 15
Total supplied ener- gy (kWh/year) 129,036 46,765 21,449 12,203 Supplied electricity (kWh/year) 107,505 13,825 21,449 0 Energy costs (NOK/year) 106,449 36,671 17,908 9,152 Investment costs, including tax (NOK)
- 4,466,000 4,578,000 6,539,000
According to the simulations, refurbishment to current building code level can relatively easily be carried through. To achieve a passive house stand- ard, the challenges are somewhat larger. The annual space heating re- quirements for passive houses are equal to or less than 15 kWh/m2. The building´s thermal bridges are a problem in achieving such a low energy demand. Results from the simulation show that it is possible to reach the passive house standard, but this requires scarifying of some functional quali- ties.
The energy supplies were also considered. A zero energy building must be self-sufficient when it comes to energy use. The main challenge for this con- cept is that the low wind speed in Drammen prevents the use of small scale wind turbines. The solar irradiance in Drammen is about 970 kWh/m2. Aim- ing for only use of solar panels for the electricity production is very expen- sive. It also demands a grid connected system. At present time there are no such systems in Norway due to restrictions for energy suppliers delivering to the grid. At present it is not realistic that Stibolts gate 13 could become a ze-
ro energy building. Recommendations for Stibolts gate 13 include reducing the energy demand considerable, and use district heating from a central heating-plant for heating and hot water. Solar cells could be included to de- liver a small amount of the electricity needed. The recommended concept is a “near to” passive house level.
Refurbishment strategy
Conclusions for Stibolts gate 13:
– Further investigations of the building's construction must be conducted, especially of foundations and the transition between wall and ceiling. – The building should be upgraded to a concept that is close to the Norwe-
gian passive house standard. The building's functionality should be im- proved.
– It is not realistic to cover the building's electricity needs with energy pro- duced at the building site based on today`s technology. This is because the site is not suitable for the use of wind turbines and a solar plant would not be economically viable.
– District heating is recommended as support for Stibolts gate 13. Alterna- tively, electricity may be used if there is a need for a reduction of costs to complete the upgrade.
Intended future use and users
The intended future use is social housing as is today.
Implementation of the strategy
The SURE project has investigated a random tender document of a typical refurbishment project of the school of Svensedammen (Drammen Eiendom KF, 2011). The SURE team has not been given access to other tender doc- uments.
A new kindergarten is recently built as passive house standard, so the strat- egy is to some extent followed. But the procurement documents of the inves- tigated tender documents are in lack of requirements regarding ambitious energy goals. Energy is barely mentioned. Therefore, the implementation of the strategy has a long way to go.
Technological solutions
The tender documents aim for a standard fulfilling the national technical re- quirements (TEK10), which is the lowest energy performance possible. There is, though, focus on the use of heat pump as energy source. One of the statements in the procurement document is as follows: “It is emphasised that the facilities will provide a good indoor climate as well as it should be based on energy-friendly and flexible solutions” (Drammen Eiendom KF, 2011).
Barriers (e.g. zoning, taxation, parking places)
The study of this specific case shows that the city planners have a positive and ambitious will to lift the buildings to a higher technical and energy stand- ard. But at some level in the company, the breaks are on. Most likely, the fi- nancial situation is not clarified. The lack of focus on energy in the investi- gated tender document also reveals a distance between strategy and action.