There are 6 steps to reduce energy consumption:
 

1. Prefabricated constructions without cold bridges and with a good air tightness. Better than 0.1 air changes per hour as natural ventilation rate.
    
2. Use of heat recovery ventilation (HRV) with low electricity use. Extra costs of item 1 and 2 are only 10.000 – 15.000 DKK per apartment (1.350 – 2.000 Euro), based on use of a new thin EcoVent HRV unit which is easy to integrate, and it is considered the cheapest way of obtaining the new Danish low energy demands with a 25–30% reduc¬tion in energy use by January 2006. Experience from implemented Danish housing projects has shown that item 1 + 2 alone can lead to a 50% reduction of the yearly heating bill and an improved indoor air climate without moisture problems.
    
3. Use of low energy windows with a good day lighting transparency and at the same time avoidance of overheating problems.
    
4. Use of solar domestic hot water (DHW) system to obtain a 50% reduc¬tion of the energy use for DHW. Extra costs 10.000 – 25.000 DKK per apartment (1.350 – 3.300 Euro).
    
5. Use of Photovoltaic modules to reach a desired or even a climate-neu¬tral low-energy level. With 0.5 kWp PV panels, equal to 3.5 m² crys¬talline PV modules, a low energy standard 1 quality can be obtained for the rooftop dwelling. Extra costs today 20.000 DKK (2.700 Euro). With an extra 2.0 kWp PV panels, equal to 14 m² crystalline PV mod¬ules, a zero energy and climate neutral energy design can be obtained on a yearly basis. Extra costs today 100.000 DKK (13.300 Euro). The use of PV energy is considered a very interesting energy option, be¬cause we know that we need to depend on renewables in the future and also because there has been a trend of a 50% price reduction in a 7 year period. In Germany 20.000 new jobs have been created in this industry in the last few years.
    
6. Use of an adapted energy supply for heating and DHW. For a low-energy standard 1 housing unit you only need a very small energy supply level on a yearly basis. All existing energy supply options can in principle be used (gas furnace, district heating, a small heat pump or electric heating). When a small air and solar roof based heat pump is used you obtain a good energy “quality” and at the same time avoid a separate energy supply (besides electric¬ity). A competitive investment cost of the energy supply system at around 25.000 – 30.000 DKK per apartment (3.300 – 4.000 Euro) is possible. In any case it is very important to avoid heat losses from the energy supply system because a normal-size heat loss will mean a much higher percentage of this in low-energy dwellings.

Suppliers of technology:

Windows:
VELUX A/S
Ådalsvej 99
DK-2970 Hørsholm
Phone: +45 45 16 4000
e-mail: VELUX-DK@VELUX.com
www.velux.com

Solar roof and PV system:
Dandis
Måløvvej 99, Ganløse
DK-3600 Stenløse
Phone: +45 3940 5500
e-mail: info@roofing.dk
www.roofing.dk

Danish Solar Energy
Glückstadtsvej 2
DK-2100 Copenhagen Freeport
Phone: +45 3943 7767
e-mail: info@dansksolenergi.dk
www.dansksolenergi.dk

Solar panels:
VELUX A/S
Ådalsvej 99
DK-2970 Hørsholm
Phone: +45 45 16 4000
e-mail: VELUX-DK@VELUX.com
www.velux.com

Heating pump system:
Gilleleje Cooling & Energy
Phone: +45 2031 1993
e-mail: gilcool@gilcool.dk

Heat recovery ventilation system:
EcoVent
Rudolfgårdsvej 19
DK-8260 Viby J
Phone: +45 7023 8802
e-mail: info@ecovent.dk
www.ecovent.com