Case Study: nZEC - Energy refurbishment of 14 dwellings in Johannesbäcksgatan, Uppsala, Sweden

Short Description

Uppsalahem began the fall of 2009 a pilot project for the renovation of one of its buildings in the neighbourhood Gröna gatan 2 in Uppsala.

The ambition of BeBo's demonstration projects is that development projects will halve its energy use. Energy calculations have been carried out to investigate and what measures could have Gröna gatan to achieve a halving of energy consumption, and calculate the savings for the measures eventually took place.

The energy saving measures chosen was mainly the installation of an FTX unit with rotary heat exchangers, individual metering of hot water, LED lighting in stairwells, additional insulation of the attic and the exterior wall inside the embrasures and renovation of windows. Total estimated the package provide an energy saving of about 50%.

Key Elements

Work with Residents

Raising awareness of energy saving  involving residents in the design process. Indivual metering of hot and cold water information to the tenants about who they can change their behaviour.

Funding

Life cycle cost analysis. Additional cost for metering this project has been financed by BeBo (supported from the Swedish energy agency).

Partnership Working

Working with external energy expert trough BeBo.

Thermal Insulation

Conventional and eliminating thermal bridges.

Windows and Shading

Renovating windows with one extra glass layer.

Ventilation

Mechanical ventilation with heat recovery.

Heating and Hot Water

District heating supply systems.

Electricity Saving Products

LED and efficient appliances.

Main Results

• The measured energy savings is about 40 kWh/sq.m (35%) compared to the estimated 60 kWh/sq.m. The figures, however, contains some uncertainty in that they are corrected to refine measurements. Further fine-tuning of the ventilation system when connecting the supply to the stairwell C can lead to greater savings.
• The package was under BeBo's calculation conditions are not profitable, largely because ventilation measure had a large negative net present value due to high investment costs, combined with increased use of electricity for operation. The computationally most profitable investment in this building was the attic insulation.
  
  
   

Lessons learned

• Lack of moisture expert in the project and that no advice from the resource poolutilization, has led to increased moisture hazards inside additions isolated batches because of the absence of a vapor barrier, and also at the undrained new scaling walls and ventilation installation in chute.
• Some steps have already been taken by Uppsalahem and other detected risk factors are under surveillance. The difficulty of access to reliable measured values for energy has complicated the evaluation work.
• Values for household and building has been inconsistent in different presentations and some measurements have only been made for the entire area Green Street 2 and not specific to pilot the building, increasing the measured values of uncertainty.
  
  
  

Additional Information

Ms Therese Rydstedt
SABO - The Swedish Association of Municipal Housing Companies
E-mail: therese.rydstedt@sabo.se
Web: www.sabo.se