The article presents the results of a study of the properties of flax straw as a raw material and as a lightweight, environmentally-friendly insulation made of a two-component mixture of flax straw and liquid glass. The flax is considered to be renewable and is a 100% natural waste product of the agriculture industry, which may be widely used as sustainable building insulation after light modifications. The ratio mixes of the two-component eco-insulation of flax straw and liquid glass (Na2O(SiO2)) have been developed in terms of sustainability principles such as environmental friendliness and energy efficiency. We used thermal analysis to compare flax straw as a raw material, and a complex insulation made of flax straw demonstrated a slower decomposition of the composite and shorter peaks, which supports the concept of the transformation of flax straw with liquid glass to increase its fire resistance properties. The peaks of the loss of mass with the exothermal process were defined for both flax samples. The thermal conductivity coefficient of the material is around 0.085 W/m K, which permits its use as an effective insulation material for sustainable buildings.

To ensure low-energy consumption in new generation energy-efficient houses, the technology of a ground heat exchanger with a heat recovery system is used almost everywhere. However, this technology has not been widely disseminated in Ukraine. The work is aimed at presenting insights from research on the combination of ground heat exchangers with a heat recovery system for building ventilation by analyzing the operational and techno-economic indicators obtained. Current studies permit revealing the optimal configuration of a ground heat exchanger with a heat recovery system for ventilation in a residential building in order to analyze the efficiency of ground heat exchangers with a heat recovery system for ventilation of a residential building in comparison with several conventional ventilation options to assess the main price/ performance ration of the process of constructing a ground heat exchanger with a heat recovery system and to determine the duration of the technological process, the labor-intensive characteristics, and the estimated cost of the technology.

Actuality. Last years the central Ukraine territories have been faced the new challenge such as the need to provide energy efficient housing and jobs (employment) for displaced people from Donbas regions. In the same time in the state level, the economic development of rural areas, as the agrarian sector is leading today. That is only the multi-disciplinary approach may provide the complex solution for rural support and sustainable development. In the context of circular economy the combination of building and agrarian sectors is logical as the building sector may propose the rational way of agriculture waste recycling and the rural infrastructure development together with new activities providing. The purpose. To develop a scientifically sound model of rural area planning development based in the integration of hybrid multi-functional building structures, taking into account the main principles of sustainable development and circular economy. Methodology. The model is based on a review of scientific work on the problem and the analysis of statistical data. It uses the methods of field research to study the features of sustainable development and energy-efficient structure systems in the rural areas. Findings. A new approach to design and structural solutions of the rural area is proposed, using the innovative hybrid system, which supports the balanced energy and information flows. In this model, the symbiosis of agricultural, administrative, and blocked individual buildings is key to the rural area agrarian building cluster unit, which is energy-efficient and autonomous (independent). The combination of environmental building technologies with modern bio-agricultural technologies can solve many of the socio-economic problems of the modern village - providing affordable quality housing, safe and useful work with green farming technologies, in tourism, and in scientific spheres. The proposed solution integrates rural area cultural and material heritage conservation as a socially important element. The research focuses on environmentally clean and renewable local materials: straw, flax, reed, hemp, earth-concrete, and others. Ideally, the proposal will achieve nearly 100% utilization, or recycling, of the construction and shell building materials in the end of building life cycle. It will also design solutions for nearly zero waste during exploitation. Scientific novelty and practical value. The spatial planning model of the region meets the basic criteria of sustainable development: economic and energy efficiency, social orientation, environmental friendliness, preservation of cultural heritage. The implementation of the proposed new planning model and building construction will facilitate balanced development and renaissance of the rural area.

Achieving carbon neutrality by 2050 is one of the European Union’s key priorities. Yet, the attitude of numerous politicians, of the professional community, and of society in general towards the threat posed by climate change is ambivalent. Arguments are frequently heard about the transition to a low-carbon economy that will be very costly, with increased unemployment, and that in reality climate change may not even be that severe. Added to this, there are human rights and freedoms, and in the case of architects and designers, the right to freedom of creation, to choice of materials, etc. The present article seeks to show that the issue of sustainable architecture and construction is not a whim, but an absolute necessity, and that true freedom lies in recognizing this fact and adapting our actions accordingly. However, even if we have the good intentions to adapt the needed actions, there is still the question of how to react in the right way, without causing myriad unwanted side-effects or being completely counterproductive. As there is not yet any comprehensive account of the history of energy-efficient and sustainable building and architecture, this paper has attempted to give a brief overview of developments in this field from a Central European perspective. Furthermore, the aim was to point out some conceptual mistakes that have been made in the past and that should be avoided.

The article presents the results of a study involving the properties of flax and hemp-based lightweight concretes as well as the initial characteristics of different straw-based materials. A comparison of straw-based lightweight concretes with and without ordinary Portland cement (OPC) showed that hemp concrete has a 5.6 % higher strength at a 10% deformation, and at the same time, has a 13% greater thermal conductivity coefficient than flax concrete. The physical-chemical study based on a thermal analysis in an air environment has shown that the overall picture of thermal degradation for flax and hemp concretes is similar. Nevertheless, additional peaks of mass loss have been defined for flax concrete. The demonstrated exothermal process is a positive aspect, considering the life cycle of the material and the recycling stage. The paper proposes reference points for the development of new building materials based on straw.