A general optimization model has been developed and applied for a representative apartment in the condominium association "Viva", which is an apartment building area planned to be erected by Riksbyggen, at Dr. Allard street in Gothenburg. The optimization model's purpose is to find the optimum supply of heat from an environmental perspective without compromising thermal comfort. The building's heating system is updated with the heat source CO

2-load, external climatic variations and internal loads, three days ahead and at the same time, the apartment’s heating system and thermal behavior is also taking into account. The aim is to assess the potential for CO2-savings depending on the choice of building structures and heating systems.

The model of the Viva's apartment shows that it is possible to control and optimize the heat supply with respect to comfort requirements, internal and external loads, and environmental damage from the heat production. The extent of CO

2 savings will be entirely dependent on how much CO2 impact of energy varies over time. A variation with a standard deviation of about 25 grams of CO2 / kWh provides savings of up to 20% for an apartment with a concrete frame and up to 16% for the same apartment with wooden frames. The difference between the heating systems; underfloor heating or air heating, is marginal in this case. On the other hand, if the standard deviation would be five times larger, corresponding to the use of margin generated heat, there could be savings of as much as 171% in the concrete apartment with underfloor heating and 145% for the same apartment with wooden frames. If air heating is used the savings will decrease by 20%-units in each case. All these findings are a result of optimization of heat source CO2-load and a comparison with the corresponding apartment controlled without optimization of heat source and were inside temperature could vary between 21-23 degrees. During optimization the temperature has been allowed to vary between 20-24 degrees.