Most of the year passive climatizing is sufficient. Passive climatizing means that the need for regulating the indoor climate (ventilation, cooling heating, lighting) is reduced to a minimum because the building design is right. The main part of the climatizing requirement can be met with solutions, which do only require limited technique.

• Orientation, the different functions are placed according to the sun. Offices are placed in the shadow as far as possible, which reduces overheating, and thereby the requirement for ventilation and cooling. The recidences are facing south. Sun is considered attractive in residences (in Denmark) and they benefit more from the passive solar heating than the offices. 

• The building complex is very compact, which means less heatloss. It is possible due to the atrium street, which provides daylight for the areas in the mittle of the building, and placing functions according to the daylight level in both recidenses and offices. 

• The external walls are well insulated in a construction almost without thermal bridges.   

• Thermal mass (heavy constructions) stabilizes the temperature and can be used for night cooling.  

• The windows are multifunctional, have a very low heat loss (U-value) and can provide ventilation without draught. Solar screening is provided between the glass panes.  

• Both offices and recidenses have natural ventilation the most of the year. The air is drawn out through the atrium street and comes in through the multifunctional windows. In the summer fresh air can be let in from the shadow side of the building where it is coolest. Spring and autumn there will be some heating of of the air, when it passes between the two panes.

• Mechanical ventilation with heat recovery provides an energyefficient regulation of the indoor climate in the cold months (2-3 months a year). 
• Possibility for nightcooling of especially the offices secures a pleasant indoor climate also in summer. There is no use of electricity for cooling. 
• The building requires very little heat supply. It covers hot water and heating in the coldest winter months. It is the plan to use district heating for the 4D project. It provides the best economy and is considered the most sustainable solution in this case. 

• All lighting integrated in the building is low energy lighting.

• The project is planned with constructions which are relatively simple to build and easy to maintain. Technical installations are reduced to a minimum which means shorter and simpeler service ducts. This reduces the risk  of damages. This is a benefit for the enviroment in itself, and it saves money which can be spent on the enviromental measurest that cost extra.

Offices 

apartments 

• The offices are better than Low Energy Class 1 according to Danish building legislation. The calculated energy consumption is 35-40 kWh/m2/year, corresponding to 35-40% of the energy demand in similar buildings, whitch meet the Danish building legislation. 
• Many offices are facing north and does not recieve any direct sunlight. Offices facing east and west which are not in the shadow are equipped with efficient solar shading. This reduces the demand for ventilation and cooling.  
• The windows are multi-functional and have automatic control of air inlet and solar shading - but with the possibility for the users of the building to overrule the system. 
• Night cooling in warm periods; the small window frames of the multi-functional windows are opened to let in the cool night air, which will cool the thermal mass in ceilings and walls. The coolness wil be released slowly from the thermal mass during the day.

• All working places recieve good and sufficient daylight, which minimizes the need for electrical lighting, which is mainly low energy lighting.

• The indoor climate is regulated by "intelligent" control mechanisms. Operation of heating, ventilation and control will be carried out by an ESCO (Energy Service COmpany), which will have an economical incentive to achieve the desired indoor climate, with the lowest possible energy consumption.

• The residences have a calculated energy demand on 25 kWh/m2/year, corresponding to 30% below the demands for Low Energy Class 1.

• The residences have manually operated multi-functional windows with solar shading between the panes. The windows are constructed from standard windows.  

• In the residences all technical installations (ventilation, heating etc.) are gathered in an installation shaft, and the funktions demanding installations are all gathered around the shaft.

• Also the heating installations are placed very close to the shaft. This is possible because the facade is highly insulated and the windows has a very low U-value. This means that it is not necessary to place heaters directly under the windows in order to achieve good comfort. The extent of the heating system can be substantially reduced compared to a "normal" residences. Most residences in the 4D-project only need 2-3 small heating surfaces (radiators).

• The bathrooms have a ventilated drying closet as alternative to the tumble dryer, which is one of the major energy consumers in a residence. A drying closet can save up to 10 kWh/m2/ year, a saving which is not part of the energy frame calculation.