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In accordance with Eurostat data, housing situation in Poland leaves a lot to be desired. Almost half of Polish citizens live in overcrowded dwellings, for which they pay too much. As much as 25% of tenants and 18% of owners spend more than 40% of their monthly income on just upkeep costs of housing1. A significant portion of these expenses come from electricity and heat demand. To mitigate these costs, numerous housing cooperatives decide to thermo-modernise apartment blocks and houses. Unfortunately, insulating dwellings without paying attention to ventilation systems can affect the airflow in the house. Dry, heated and dusty indoor air negatively influences health and general well-being of people. As a result, the incidences of Sick Building Syndrome (SBS) occur more frequently. People, who are suffering from SBS may experience eye, nose and throat irritation, chronic tiredness and lowered ability to focus their attention. All of these symptoms are caused by simply being exposed to indoor air2. Health problems and high costs of living influence the feelings of dissatisfaction and decrease human productivity.
While analysing the above information it is easy to come to conclusion that rapid development of new construction technologies is a high priority issue. It is important to plan solutions that will not only lower the housing expenses, but also improve the comfort of life and conditions of the surrounding environment. The idea of passive and plus-energy housing is the answer to the increasing needs of housing situation. A passive house does not need external energy supply or requires only a minimal amount of it. Electrical energy and heat are produced by integrated renewable energy micro installations, such as photovoltaic panels. Possible energy losses are mitigated through appropriate design, the use of high-quality building materials and heat recuperation equipment. If a house produces more energy than it is needed for its upkeep, it is called a “plus-energy” building. Surplus energy may be stored or distributed to the grid, where they may be sold.
In compliance with EU Directive 2010/31/WE, all Member States are obliged to ensure that by 31 December 2020, all new buildings are nearly zero-energy buildings. At the same time, Member States are responsible solely for setting minimum requirements for the energy performance of buildings and building elements. The choice of technology and building method is left to the investor’s conscience. In accordance with European Union laws, National Fund for Environmental Protection and Water Management (PL-NFOŚiGW) and Polish National Energy Conservation Agency (KAPE) set a number of requirements for two types of low-energy houses. These standards (NF15 and NF40) apply to buildings with target grid energy consumption of no more than 15 kWh/(m2*year). The main difference between these standards is target efficiency of energy saving systems. In NF15 buildings, passive houses, efficiency goals are set at 80-93%, depending on the type of the building. Houses under the NF40 standard have lower energy demand, with target efficiency oscillating around 70-85%4. It has to be noted that both NF15 and NF40 buildings may eventually save more energy than it was planned in the initial project or even reach the plus-energy status.
To reach outstanding energy standards, passive and plus-energy houses are equipped with numerous technologies, which allow to minimise heat loss. Energy saving systems can be divided into two groups: passive and active. The first one prevents heat from escaping, while the second one recapture heat from ventilation. Passive solutions require no energy input and active devices utilise electricity produced by integrated renewable energy micro installations. Both systems cooperate in preserving energy balance indoors.
Passive systems are usually construction-based. Conventional building materials, such as Styrofoam or steel rebar contribute to heat loss and increasing energy expenses. Passive and plus-energy houses are insulated with highly efficient materials i.e. foam glass. It is an environmentally friendly material, which is made from glass waste with foaming and ash additives6. Foam glass gravel can then be melted into bigger bricks and used for thermal and acoustic isolation. It is an inorganic, mold- and weather conditions-resistant material. Additionally, due to its water resistant properties it can be utilised for wall and floor hydro isolation.
One of the most prevalent reasons for heat loss is the occurrence of the so-called thermal bridges in buildings. When two types or thicknesses of a building material are joined, the sudden change in physical parameters lowers heat resistance of the joint. Heat “escapes” through gaps between concrete slabs or bricks and along heat-conductive rebars7. For passive and plus-energy housing needs, Green Energy Cluster offers an innovative technology of composite rebar. They are made from a non-uniform mixture of various building components. Composites have a high tensile strength capacity, they are non-corrosive and resistant to potent acids and bases. They do not conduct heat, which allows for minimising heat loss. Concrete slabs used for passive and plus-energy building construction should be made from expanded clay concrete. Unlike standard gravel concrete, it is light and non-hygroscopic. It prevents outer walls of the building from getting soaked and losing heat for evaporation processes.
An active device called a recuperator is integrated with passive systems. The most important part of the recuperator, the heat exchanger, is a place where a stream of cold outdoor air passes by warm indoor air without mixing. The air that enters the room is pre-heated. Target efficiency of a recuperator is described in the Polish Norm PN-EN 308. It can reach a level of around 95% in case of the most advanced devices, like MISTRAL PRO manufactured by a Polish producer ProVent8.
It has to be noted that the importance of heating systems in passive and plus-energy housing is reduced to a minimal level. Heat inside the building comes from the outside or is a by-product of the activity of house inhabitants and electrical equipment. Health benefits of reduced heating system use are enormous: dry air can cause the irritation in eyes and mucous membranes. Long exposure can also lead to tiredness and general feelings of being unwell. Utilising alternative heating technologies can be also beneficial to people suffering from allergies or various skin diseases.
Construction solutions itself are, however, not the only innovative features of passive and plus-energy housing. Equally important are micro installations integrated with the home network, which produce energy from renewable sources. In case of passive housing complaint with standard NF15, the systems of renewable energy sources (RES) should reduce the demand for the usable energy for heating and ventilation till the maximum of 15 kWh/(m2* year); plus-energy houses should ultimately produce more energy than it is required for their functioning. In the guidelines, developed by the National Fund for Environmental Protection and Water Management (PL- NFOŚiGW) as well as by the Polish National Energy Conservation Agency S.A. (KAPE), the following renewable energy sources are listed:
Poland characterizes itself with a high potential as regards deriving renewable energy sources. The most frequently used small –scale investments are photovoltaic panels. In theory, possible potential of solar radiation in Poland amounts to approx. 1340 PJ yearly. The vast majority of this energy is attributed to spring and summer seasons. Till 2020, technological and financial opportunities should allow to use approx. 20 PJ, which represents 2% of the annual domestic demand. Photovoltaic panels are silent, non-invasive and aesthetic installations. That is why they are chosen to work with the systems of passive and plus-energy houses. The most common problems associated with the use of panels are insufficient sunlight and light scattering – they can be easily prevented by project solutions, which take into account the direction of the incoming sunbeams and location of a panel.
Not all areas in Poland are characterized by the favourable solar irradiance. On the areas with relatively low annual solar irradiance (e.g. in Masuria) there is a possibility to make use of different technology. One of the possible energy sources is wind. There can be distinguished two major factors influencing the opportunity to use it for energy targets – speed and repeatability. Based on the analysis of these two properties, the analyses of wind energy sources for Poland has been developed. Approximately 85% of the country’s surface is defined by favourable or very favourable conditions for the production of wind energy. However, conventional turbines may have a negative impact on the living comfort of the residents and aesthetic valuables of the region.
Technology suggested by Green Vertical Turbine LLC (PL - Sp. z o. o.) looks especially impressive. The company deals with the production of wind turbines with vertical spin axis. Contrary to popular horizontal windmills commonly encountered in the landscape, vertical turbines are built with independent segments, which can be connected into modules. Segmented construction facilitates easy transportation of power station, which enables its installation not only on the open area, but also on the roofs of buildings and other places not accessible for traditional turbines. Vertical turbines are silent and does not pose a threat to birds and bats. Thus, they constitute a perfect solution, which work out on the estates of passive and plus-energy houses.
Investment in passive and plus-energy housing involves a number of benefits not only for the resident, but also for the owner of a building plot. Residential housing is an inherent element of the economic and ecological landscape. Seemingly small elements, such as smoke coming from the chimneys or “flashing” shadow cast by the turbines of conventional windmills may negatively influence the perception and look of the area. That is why clean, efficient and reliable housing of high standard is optimal from economic, ecological and social point of view.
A resident of a house or apartment built in passive or plus-energy technology will directly take benefits resulting from living in such a building. Reduced costs for electricity and heating will relieve the family budget. Reducing the role of the heating installation means that in case of its failure, the temperature in the building will not be decreasing sharply. This is particularly important in winter, when failure of the heating network can cause many difficulties. Deriving electricity from small, domestic installations solves the problem of the energy transport and reduces losses associated with possible damage of the transmission network. In addition, living in an environmentally friendly building will appeal to tenants, for whose environmental protection issues are important.
Benefits for self-governments result not only from the growing levels of satisfaction of tenants, though it is a very important issue. Equally important is a perspective of ensuring energy independency of the given area. Issues regarding maintenance of the natural environment shouldn’t be underestimated. Emissions that come from conventional power stations will cease to disfigure the landscape of precious natural areas, which positively impacts a life comfort in a given region. Investing in renewable energy sources can be used for building a good image of a municipality or district, increasing touristic traffic and developing urban and rural areas.
Despite a rapid development of passive technologies, the cost of building the facility with the low-energy consumption is substantially higher than the cost of building the comparable facility built with traditional methods. Investment in passive and plus-energy housing may be supported from the budget of the National Fund for Environmental Protection and Water Management (PL - NFOŚiGW).
The level of co-financing depends on the size and the character of the apartment:
Housing market in Poland is currently undergoing a rapid development. A significant demand for building new housing is caused by high life dynamics of Polish society. Moreover, in accordance with the Directive 2010/31/WE, Poland is obliged to increase the amount of low energy consumption houses and apartment blocks. To address these two issues, the National Housing Fund has recently introduced an investment scheme under the name "Flat +". Its main objective is the construction of plus-energy houses, which will be available to Polish citizens living under the poverty line. It is estimated that 500.000 buildings will be constructed, with their net worth of 300.000.000 Euro.
In addition to this, there are also funds financing the purchase of devices producing and using the renewable energy and saving energy. For help in obtaining funds for building a passive house one can consult advisors. In Poland such activity is conducted by the Investment Service Centre. It serves comprehensive services in the field of designing passive and plus-energy houses, advisory, risk assessment of the undertaking and obtaining subsidies for construction.
It should also be mentioned that costs of construction a facility with low – energy consumption reimburse during more than a decade. It results from savings made during the use of the flat, as well as the possibility of sale of the excess energy to the network. This sale can be direct or take the form of preferential prices of the choice of energy with the network. In compliance with the amendment of the Act about the renewable energy sources, prosumer will not incur for the energy of 0.7-0.8 of the introduced energy any charges depending on the amount of consumption, that is active energy, variable transmission fee and fee for the quality.
Human settlements are still perceived as a dualistic concept of "natural environment versus the area of human activities”. Passive and plus-energy houses can be seen as an attempt of harmonious combination of these different environments - they are favourable solutions both for the resident and for the landscape surrounding this resident. Definition of a sustainable development comprises the necessity of conscious development of relations between the economic, ecological and social values is indicated. In this perspective passive and plus-energy housing is a perfect example of implementation of the programme of sustainable development.