This article proposes to contribute to the discussion on environmental product declarations for buildings. Using a simple life-cycle analysis of a low-energy detached house and CO2-equivalent emissions as a comparative unit, the case study presented illustrates the problems with the initial input data related to embodied energy and a definition of the criteria for an assessment of the environmental quality of buildings. The actual case study compares the expected energy demand of a detached house in the course of its service life and the energy input (embodied energy) necessary for its assembly and for the manufacture of the individual building products. The operation of the building during its service life is described using a computer-aided building performance simulation. The input data related to the embodied energy are based on information from classical works on life cycle analyses. In addition, the article discusses the limits of building envelope improvements in terms of the thickness of thermal insulation and also stresses the increasing significance of embodied energy in the environmental assessment of buildings.

The article deals with the importance of low-emissivity glazing layers to improve energy balance and their significance in maintaining interior visual comfort. It describes the physical nature of radiation and the associated surface emissivity and the effects of changes in surface emissivity of glass, depending on the position of the low-emissivity layer. The paper also discusses principles, advantages and disadvantages of the most common combinations of glass and a low-emissivity layer the so-called “high performance” glass and the so-called “low-e” glass.

The article presents environmental analysis of a detached house in terms of its life cycle. The analysis is simplified in order to compare the built and operational energy of the building whereas the operational energy is described using computer aided building performance simulation. The input data related to the built (embodied) energy are based on information from classical works on life cycle analysis. The article also justifies the simplification of environmental analysis, which aims to build pragmatically on existing standardization and legislation on energy performance of buildings. The final section provides some considerations concerning the environmental assessment of buildings.

Extensive roof greenery is one of the ways to reduce the extent and impact of urban heat islands. A prerequisite is the correct design and operation of both the structural and vegetation part of a roof. If adequate maintenance, especially irrigation of the greenery, cannot be ensured, the use of extensive roof greenery can also be counterproductive. The case study to be presented deals with problems of a flat roof with extensive greenery above an underground garage under Central European climate conditions. Infrequent irrigation leads to extremely high temperatures of the substrate in the summer and makes the purpose of this roof pointless. The contribution analyzes the reason for the failure of the vegetation part of the roof, which was claimed to be maintenance-free, points out fire safety issues, and suggests improvements that might be considered in similar cases. At the present time, which is marked by the climate change crisis, there is great societal pressure to build green roofs. However, if it is not possible to ensure their perfect functionality, it is perhaps better to use classically proven types of roofs, but with greater reflectivity of the top layer surface.

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