The ideal house is an energy efficient building, friendly to the environment and people. Today we can consider sustainable buildings that not only use very little energy, but even produce it. The first most energy efficient building in the Baltic countries will be hosted in the capital of Lithuania.
Saving rapidly depleting energy resources has become increasingly important, therefore, so-called passive houses consuming as much as 10 times less energy than usual are no longer surprising. Energy efficient apartment buildings are being built with an annual energy consumption of up to 15 kWh m2, compared to the normal rate of 120-150 kWh m2. Starting in 2020, it is only these types of new homes that will be built across the European Union.
While there are already energy-efficient residential buildings in Lithuania, no investments have been made in sustainable commercial buildings. The Baltisches Haus real estate development company decided not to wait for the EU-mentioned term and has started to construct the first in the Baltic countries, the most energy efficient – A++ energy efficiency class – building near Vilnius, a shopping centre ŽALI in the Balsiai settlement.
The efficient energy performance of buildings means cost saving energy consumption, measured in energy classes. B, A and A+ classes of buildings are in the category of low energy buildings and A++ are almost zero, which corresponds to the highest requirements to be made mandatory from 2020. Remigijus Simanavičius, director of the Energinis efektyvumas plius company implementing the energy performance project of the ŽALI shopping centre lists the tools for the achievement of such energy efficiency and sustainability.
“The purpose of energy efficiency is not just saving, but seeking environmental comfort with the lowest possible energy cost. For instance, the future trade and service centre (3500 m2) will be heated by a geothermal power plant that will accumulate geothermal heat. In the summer, the same power plant will run in reverse mode by directing heat from the building into the earth for cooling the building. For this purpose, shafts up to 25 m deep should be drilled under the ŽALI building, with installed heat pump equipment”, said R. Simanavičius.
According to him, along with the saving of heat energy, the building will also have ventilation equipment with heat recovery. Such a ventilation system prevents cold air from the outside from entering the premises during the winter by heating the cold air with discharged warm air in a heat exchanger. Another important aspect of energy-efficient buildings is the absence of building leaks. The tightness of an A++ building has to be so high that the air exchange rate does not exceed 0.6 times at 50 Pascals pressure.
Not only are energy-saving measures important. ŽALI will also feature a smart building managing system – BMS (Building Managing System). It will consider even seemingly minor increases in heat, which may he caused by functioning store fixtures, display cabinets or refrigerators. Usually these are disregarded, but every detail is important in an A++ building.
It is now possible to simulate the behaviour of the building under different atmospheric conditions while still in the design stage. A so-called dynamic simulation is used for it – a computer program where the 3D building model is assimilated, by imitating the behaviour of the future building in a virtual space, and taking into account all the possible climatic and operational impacts. This program allows tracking the life of the building hour after hour throughout the year.
With conventional calculation methods, the future average energy costs can only be estimated approximately, but they can vary greatly from reality. “Dynamic modelling allows knowing the future energy costs very precisely and for a specific part of the building; it also provides means to adjust them, if necessary. In this way, dynamic simulation allows abandoning the energy reserve, which is inevitable in the calculation of the project by the conventional method”, says R. Simanavičius.
The ŽALI project developers, Baltisches Haus, are focused at record low – only 10 kWh m2 per year – energy costs. Already, in the environmental impact assessment system BREEAM scale, from the energy point of view, this building is estimated at least 10 points out of 15, i.e. very well. This is the first commercial building in Lithuania still at the design stage to achieve a high environmental assessment rating from a recognized international standard.