In Polish conditions, one of the types of investments which bring financial benefits for the investor and also reduce the load of the environment is thermal insulation. This article shows how to make an evaluation of sample of investment, which is the thermal insulation of the exterior boundary walls, from the financial side. Indicators to assess the investment in ecological terms, using life cycle assessment LCA are also proposed. An analysis of different options depending on the thermal insulation was made. Analysis includes: properties of the exterior boundary walls against thermal insulation, the type of thermal insulation and type of heat source in the building

Plaster plays an important role in the building industry. Besides an aesthetic function it provides the protection of external walls from weather conditions. In the paper thermo insulating Thermopor plaster was described. Its chemical and physical properties and manner of using were defined. The impact on the environment with the use of LCA technique was examined. Thermopor plaster can fulfil a thermo insulating function. The economic and ecological analysis of applying this plaster in the thermo insulation of the external walls of the building was conducted. The use of Thermopor plaster on external walls brings ecological benefits. The reimbursement of ecological cost related to the use of this plaster appears already after 2 to 5 years, depending on the source of heat used, which results from the decrease of thermal energy consumption for heating the building. For economic reasons, the partial reimbursement of cost is obtained as a result of the reduction of heating cost. Although Thermopor plaster has thermo insulating properties similar to typical insulating materials, such as polystyrene or mineral wool, the economic cost of using the plaster for thermo insulation becomes several times higher