Energy efficiency measures have been analysed for a building of around 24000 m2 from 1978. The property is used by different businesses. The specific energy use for this property is 75 kwh/m2 for electricity and 114 kwh/m2 for district heating. This projects ambition is to go lower than the Norrbotten county councils specific energy objective for their real estate facilities. The specific energy objective for year 2020 is that the use of electricity should be maximum 68 kwh/m2 and 102 kwh/m2 for district heating.
The result of the energy audit for the biggest energy consumption users (ventilation, heat and cooling) for the property is that 56% of the electric consumption and 15% of the district heating demand was identified. The 56% can be divided in different parts: 44% ventilation, lighting 22%, climate control equipment 16%, cooling equipment 10% and engine warmers 8%. In this project 14 of 19 ventilation units are studied and the reason that all are not part of the study is lack of information. The proposal for action was determined for 10 of the 14 ventilation units. The 4 remaining ventilation units were not possible to analyse partly because of lack of logging of energy consumption where frequency converter were used. One of the omitted units had only a fan for supply air and no heat exchanger.
For each of the ventilation units in the group of the 10 selected an analysis was made selecting the most cost effective measures of the alternatives; installing a new ventilation unit, installing a frequency converter or replacing the motor of the unit.
The result of energy audit showed that adding extra insulation to the roof and upgrade of the ventilation system are recommended actions. All recommendations are estimated based on an evaluation of the power consumptions in real use denoted as average power of the ventilation units.
Proposal A suggests to install one new ventilation unit, install frequency converters in 5 ventilation units and replace motors in 4 ventilation units. Energy saving of electricity of these actions is 232 MWh and 174 MWh for district heating and the payback time is around 2,7 years.
Proposal B suggests that 10 ventilation units are replaced with new ones. The energy savings of electricity will be 206 MWh and for district heating 237 MWh and the resulting payback time is about 6,4 years.
Proposal C is adding extra insulation to the roof and this provides a very cost-effective energy saving. If the roof was insulated with 20 cm the energy saving would be about 260 MWh and the payback time would be around 1,6 years.
If additional insulation of the roof is installed as proposed in combination with upgrade of the ventilation system, the total energy consumption saving of 15 % is achieved from 4427 MWh to about 3761 MWh depending on choice of ventilation upgrade. (Proposal A+C 3761 MWh and proposal B+C 3724 MWh).
The investment cost is around 1,5 million kr for proposal A+C and the yearly saving is 0,7 million kr resulting in a payback time of 2,3 years. The specific electric consumption would be 65,3 kwh/m2 and the specific district heat consumption would be 95 kwh/m2.
The investment cost is around 3,3 million kr for proposal B+C and the yearly saving is 0,7 million kr resulting in a payback time of 4,7 years. The specific electric consumption would be 66 kwh/m2 and the specific district heat consumption would be 93 kwh/m2. Proposals A+C and B+C both archive the Norrbotten county council’s goal for the specific energy consumptions for year 2020.
2016. , 44 p.
Energieffektivisering, Energieffektiviseringsåtgärder, Energieffektivisering av fastighet
Gunnar Karlsen Sverige AB, Luleå, Magnus Rönnberg, email@example.com