The year 2021 is inevitably coming, in which all newly built buildings should meet the standard of almost zero-energy all newly build constructions (nZEB). This means that buildings should have almost zero or low energy consumption. The energy demand should be covered to a very high degree from renewable sources, including renewable energy produced on-site or nearby. One of the renewable that can be used is solar energy, which for the 9th time in a row has achieved the largest share (42.5%) of new investments utilising renewable energy sources. Currently, solar energy is most often used by photovoltaic cells, which converts it into electricity. Over the past 15 years, the accumulated annual growth rate of photovoltaic production has been over 40%, which means that the photovoltaic industry is the fastest growing in the world. The annual capacity of new solar installations installed has increased from 29.5 GWp in 2012 to 107 GWp in 2018. The development of solar technology is huge. Previously known technologies are improving and refined, which stands for that the efficiency of electricity conversion is increasing. New innovative technologies using photovoltaic cells are also emerging. These include cells dedicated to the building facade BIPV, used in louvres of curtain blinds, filling mullion-transom facades, roof skylights or balustrades. NanoPV windows are a new product appearing on the market. This is a product that uses innovative material - quantum dots, i.e. small semiconductors with the sizes of several or several dozens of nanometers, having the ability to absorb and emit electromagnetic radiation. In this work, the authors present the development of photovoltaic technology and the most interesting solutions according to the authors regarding the use of solar technologies.

Directive (EU) 2018/844 of the European Parliament and of the Council of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency introduces a zero-energy building standard, for which the energy balance per year is zero, i.e. the amount of energy obtained from renewable sources is equal to the annual demand. Each Member State shall establish a long-term renovation strategy to support the renovation of the national stock of residential and non-residential buildings, both public and private, into a highly energy efficient and decarbonised building stock by 2050, facilitating the cost-effective transformation of existing buildings into nearly zero-energy buildings. To achieve energy consumption at an appropriately low level in an existing building, you must adjust the heat transfer coefficients of the building envelope and the demand for primary energy to the requirements of the Technical Conditions for year 2021. Renewable energy sources, primarily from the sun, will also play a key role. A computational example of a single-family building shows which partitions are best modernized, what thickness of thermal insulation materials should be used to properly reduce heat transfer coefficients, and which installation systems to use to reduce the potential energy index (EP). It is also depicted as to how much the demand for usable energy in the building will decrease. This article aims to show residents of single-family buildings what steps should be taken to reduce energy consumption and thus - operating costs in an existing building to a minimum.

Wood-based construction is a rapidly growing branch of construction in the world, it is slightly worse on the Polish field. In the era of care for the environment, it is important that newly constructed building objects, including buildings, not only use as little energy as possible, but are also made of materials received as ecological. Wood-based construction combines both of these aspects. There are, however, two other market aspects: price and availability of materials and technological solutions. Wooden buildings are more environmentally and human friendly than other material solutions, and with proper insulation, finishing and well-chosen installation systems, they can also be tempted to become a zero-energy building, i.e. one whose energy balance is zero per year. Among the architectural design offers today you can find a large number of residential or public building designs (low or large volume) with a wood-based structure, both in terms of bar solutions (generally seen through the prism of skeletal objects), as well as massive structures (today mainly seen through the prism plate objects). Each of them has different design assumptions, but in principle the goal is common. The right kind of construction, insulation and finishing materials should be chosen for each. For structural elements, various types of protection should be taken, e.g. in the field of fire safety or against technical wood pests, etc. In the field of insulation, analyses of thermal issues, waterproofing and wind protection are undertaken. The choice of finishing materials should also take into account solutions that are the least burdening the environment and minimize energy losses, among others by avoiding possible thermal bridges. This article attempts to present the topic in a synthetic way, outlining global trends and possibilities of the Polish wood-based construction market. The calculation example illustrates the heat balance and environmental loads of a single-family wooden building with thermal insulation selected so that the building envelope meets the current requirements given in the Technical Conditions.

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