Kodumaja houses are energy-efficient

Requirements for thermal insulation and energy efficiency of buildings have recently become much stricter everywhere and, by all appearances, will become even tougher in the future. After all, energy efficiency is a future-oriented issue because energy resources are scarce and energy carriers tend to become increasingly expensive over time. Moreover, the use of energy-efficient solutions has been given all kinds of political support.

The structures and technical solutions developed by Kodumaja enable the construction of buildings with different energy consumption which meet the customers' requirements and comply with applicable norms in our markets. The technical solutions of respective building structures and utility systems have been developed and put into practice.

Estimated energy consumption of energy-efficient house	Estimated heating capacity of solar panels

The energy efficiency of buildings is influenced to a great extent by the materials, technical solutions and equipment used in the technical systems of a building. To assess the energy efficiency of a building as a whole, it is necessary to take into account all different components, calculate heat losses and draw energy balance. Kodumaja uses for this purpose internationally recognised software developed specifically for passive houses. Kodumaja actively cooperates with the Energy-Efficient Building Core Laboratory of the University of Tartu to find solutions for the energy efficiency problems of buildings.

The final confirmation of a building's quality and energy consumption may be obtained only by measurements in completed living spaces.

Measurement of air tightness of living rooms	Thermographic imaging of a section of living room

The analysis of measurements provides valuable information about heat losses, thermal insulation of the building structures, effectiveness of technical systems and consumption habits of occupants. This information serves as input for planning and implementing subsequent steps in product development.

Feedback from many occupants of Kodumaja houses about the actual energy consumption confirms the validity of our calculations and efficiency of the structures and technical solutions.

The final average heating energy consumption of residential buildings produced and built by Kodumaja have been found as follows:

• apartment buildings with standard structural solutions and standard exhaust ventilation from "wet" rooms (without heat exchanger) - approx. 87-97 kWh/m2 a year
• apartment buildings with standard structural solutions and balanced exhaust ventilation from "wet" rooms (heat exchanger efficiency approx. 80%) - approx. 61-68 kWh/m2 a year
• houses with standard structural solutions and application of an air source heat pump in a heating and ventilation system - approx. 64-74 kWh/m2 a yearhouses with improved structural solutions and an improved heating and ventilation system (ground source heat pump combined with exhaust air heat exchanger) - approx. 38-48 kWh/m2 a year

The estimated energy consumption of small houses developed by Kodumaja as energy-efficient houses enables us to forecast their final heating energy consumption at the level of 25-48 kWh/m2 a year (depending on the structures and technical systems used).

Estimating the energy consumption of one's living rooms, it is necessary to include, in addition to heating energy consumption, energy costs of home appliances (cooker, oven, electrical stove, TV, radio, refrigerator, lighting, etc.) and hot water, which largely depends on the number of occupants and their consumption habits.

Upon a customer's request we are ready to produce and build residential buildings in accordance with passive house standards. However, our calculations show that in the Nordic climate the pay-off period of the extra expenses required to build such houses is approaching 30 years.