The attempt at a more sustainable land use by increasing urban density may have a negative effect on the daylighting of residential buildings. In densely built areas, obstructions generated by the ...surrounding buildings can substantially reduce the available amount of daylight, causing poorly daylit spaces and a less healthy indoor environment with higher electricity consumption as a consequence of artificial lighting. European standard EN 17037, Daylight in Buildings, was established in 2018 to ensure appropriately daylit spaces. In this paper, a three-step methodology was developed to investigate the relationship between certain urban planning parameters and the daylighting of a typical room defined by specific (Slovenian) legislative restrictions about its geometry and minimum required window to floor area ratio, in order to establish the maximum densities of residential developments still fulfilling the minimum requirements for daylight provision defined by EN 17037. The results show that a relatively low urban density is required to fulfil the stipulations for minimum daylight provision for the deepest permissible room according to the Slovenian legislation. The impact of the development floor area ratio on the daylighting potential of buildings was identified as significant, followed by the site coverage, development layout, and building typology. Furthermore, the developed methodological approach clearly demonstrates a substantial potential for application in urban planning, with indoor daylight environmental conditions being linked to the planning of residential developments in the earliest stages of the project.
Since the non-image-forming (NIF) effect of daylight on the human circadian system is widely accepted, adequate exposure to daylight is now considered one of the elements of a healthy life. In urban ...environment, one of the prerequisites for adequately lit indoor spaces is the amount and quality of daylight reaching the window, which is highly dependent on the characteristics of the urban environment. The aim of the study was to determine whether there are correlations between urban density (i.e., distance between buildings, building height), façade surface characteristics (i.e., colour and Window-to-Wall Ratios – WWR) and NIF potential of daylight. The study was conducted on a parametric geometric model of a street canyon covering a wide range of characteristics. Simulation results were interpreted using the Relative Melanopic Efficacy coefficient and Sky View Factor. The results indicate that the colour of the opposite façade can substantially impact the resulting NIF potential, especially for orange-red or blue hues. The results of the study show that this influence for building heights between 3 and 8 storeys becomes significant when the width of the urban canyon is less than 25 m and becomes substantially smaller at WWRs above 30 %.
•Parametric evaluation of daylight spectral composition and urban canyon properties.•Façade colour effect becomes significant at urban canyon height-to-width ratios ≥1.•NIF daylight potential in urban canyons is directly correlated to urban density.•Increasing the WWR reduces the impact of façade colour on NIF daylight potential.•Results underscore the importance of façade colour in urban design decisions.
Due to the profound impact that building sector has on the environment and consequently the sustainability of our society, the evaluation of environmental impacts through life cycle assessment (LCA) ...should become part of building design. The number of published environmental product declarations (EPDs) is growing, which indicates that they can become valuable tools for building designers to evaluate the environmental performance of construction works. We identified that in the current EPD scheme an important part is missing – the results interpretation. In order to evaluate the environmental performance of buildings or their components and elements, the designer is “forced” to conduct a comparative assertion on a population of alternatives. The paper explores the results interpretation of LCA data in the context of the EPD scheme for building products and presents a comparative assertion method, which could guide designers through the results interpretation step of LCA. The proposed soft comparative assertion method was tested on a sample of external wall assembly alternatives and the results show that it significantly simplifies the LCA results interpretation and enables straightforward decision making. However, the method is not yet a fully functional tool and should be upgraded in order to make the decision process more robust and less subjective. With this paper we wish to encourage further research on the described topic, which is vital in order to add credibility to the EPD scheme as an instrument for lowering the environmental impact of the building sector.
•Evaluation of environmental impacts by LCA should become part of building design.•Comparative assertions required in order to evaluate LCA data from EPDs.•No guidelines for building designers at the LCA results interpretation step.•Presentation of comparative assertion method framework for building designers.•Developed method significantly simplifies the decision making process.
Colour of interior surfaces has to be considered in order to provide optimal visual and non-visual performance. Colour selection is often related to the occupant's colour preferences. First part of ...the presented study was a questionnaire-based cross-sectional study among the employees of the University of Ljubljana conducted in December 2019 in order to identify possible association between personal determinants, room typology, preferred colour of indoor surfaces and general colour preferences. Based on the findings from the survey results, a simulation study on a generic cellular office was executed in order to evaluate the implications of occupant's wall colour preference on the resulting non-visual luminous environment under the climate of Ljubljana. Results showed a strong association between the general colour preference and wall colour preference. Significant differences between gender and age groups were identified. The respondents preferred white, orange and blue coloured walls, the latter two, as deduced from the simulations, may have a substantial negative or positive impact on the spatial distribution and duration of appropriate non-visual exposure in the indoor environment. The results of the presented study highlight the importance of considering the potential impact of indoor surface colour selection when evaluating the quality of the indoor luminous environment.
Identifying environmental hotspots and comparing design options are the most common goals in building life cycle assessment (LCA). Our paper focuses on the latter by identifying and evaluating ...various concepts for interpreting LCA results that can be applied when comparing multiple design options. The term LCA interpretation concept is introduced. Eight approaches were analysed and classified into three groups; (i) raw LCA data, (ii) benchmarking and (iii) single score indicator interpretation concepts. Features and attributes for making sense of LCA data were defined and used to evaluate how the investigated LCA interpretation concepts support decision-making. Finally, the results were compared and evaluated whether the applied LCA interpretation concepts could influence the designer's perception of environmental superiority. The outcomes show substantial differences in the ability of LCA interpretation concepts to support the decision-making process. Benchmarking, weighting and normalization are essential to making environmental decisions when comparing multiple design options coupled with multiple environmental indicators. Otherwise, the risk of decision-making dilemmas due to data overflow is high. Our case study with 21 design options showed that the perception of environmental superiority and inferiority may be conditioned by the selection of the LCA interpretation concept.
In recent years the use of wood based products in building industry has expanded. Although lightweight timber constructions essentially decrease environmental impact of a building, their ...consequential low thermal mass can lead to overheating during summer. Therefore, the purpose of this paper was to investigate various examples of enhanced lightweight constructions from the thermal response point of view. Several improvements were investigated (e.g. clay boards, wood wool thermal insulation, Phase Change Materials, etc.) and compared with the performance of a conventional thermally insulated high mass wall. Finite element model was created and dynamic thermal performance of enhanced lightweight external walls was analysed in three different European locations: Helsinki (Finland), Vienna (Austria) and Madrid (Spain). Certain enhancements resulted in lower internal surface temperature of constructions up to 1 °C, depending on location. In addition, it was shown that in order to further improve thermal performance, application of high intensity ventilation is necessary, which additionally lowered the internal surface temperature up to 8 °C. It was shown that enhanced and naturally cooled lightweight constructions are more suitable for locations with milder summer temperatures (Northern, Central Europe), rather than for hot climates (Mediterranean). It was concluded that the application of lightweight constructions should be thoughtful in order to achieve adequate thermal response of buildings. However, in lightweight buildings the integration of materials characterised by high thermal mass, high thermal effusivity and low environmental impact should be encouraged.
•Dynamic thermal response of various lightweight constructions was studied.•Calculations were executed for summer conditions in 3 typical European climates.•Thermal response of constructions was improved with various enhancements.•The most effective improvements were wood wool, PCMs and intensive ventilation.•Lightweight constructions were shown as least suitable for hot climates.
The difference between the functioning of the human non-visual and photopic systems has elicited the need for complex in situ measurements or time-consuming multi-spectral simulations to accurately ...predict the non-visual luminous content of the indoor environment. As such methodologies are time-consuming, the aim of the present study was to determine whether such complex methodologies are needed. The issue was studied through simulations of four cardinally oriented identical offices located in Ljubljana, Slovenia. Each was studied using orange, grey and blue walls. Diurnal luminous conditions were studied under clear, hazy and overcast skies on December, March and June 21st. The non-visual content was evaluated using novel metrics, the Autonomy of Circadian Potential and Circadian Autonomy, which assess temporal circadian luminous content. Diurnal results were used to construct climate-based spectral months to evaluate the monthly non-visual potential of the studied offices. Furthermore, simulations addressed the question of whether the requirements of the non-visual system might contradict the visual comfort of indoor environments. The results show that compliance with non-visual requirements for indoor spaces with spectrally neutral surfaces or those in shades of blue could be assessed using photopic methodologies. However, this is not true for spaces characterised by orange and red materials.
Off-site construction can represent a potential solution for worldwide mass housing demand and has gained a lot of attention during the refugee crisis in Europe. In particular, modular construction ...is one of the most cost-effective off-site methods for various types of buildings. Its characteristics are cost -effectiveness, quality control and quick on-site assembly. The design challenge is to join the stated advantages with operational sustainability, which is susceptible to climate-determined and energy efficient design. Therefore, the purpose of this paper was to systematically evaluate energy and visual (daylight) efficiency of singular prefabricated modular unit. In order to emphasise the relevance of local climate, modular unit model was analysed at five different locations, monitoring cooling, heating and lighting energy use. Results showed similarities and differences between the analysed locations and implemented design measures. The conducted analysis included variation of orientation, window to wall ratio, window distribution, envelope thermal transmittance and glazing characteristics. Surprisingly, the results indicate substantial impact of artificial lighting on the total energy use. Therefore, emphasising a direct connection to the Spatial Daylight Autonomy (sDA) values of the modular units. With sDA values below 50%, lighting can represent up to half of the total energy use.
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•Coupled daylight-energy simulations of prefabricated modular units were performed.•Envelope configuration was optimised in regards to four different climatic types.•The results emphasised the impact of artificial lighting on the total energy use.•There is a direct connection between Spatial Daylight Autonomy and energy use.•Climate optimised envelope configuration is crucial for achieving sustainability.
•Transient thermal performance analysis of typical external walls was conducted.•Light and heavy weight walls were compared under typical summer conditions.•Light walls exhibit larger fluctuations ...and mean values of indoor temperatures.•The effect of passive cooling is dependent on the wall type and configuration.•Thermal insulation position is identified as a decisive factor in thermal response.
Quality of indoor environment as well as energy consumption in buildings are a growing concern in the context of overheating of buildings, as the EU legislation is primarily focused on heating season. The statistical data of EU have shown that there is already a large amount of buildings not comfortably cool during summer and the trend is increasing. Therefore, the main goal of this paper is to evaluate the influence of high intensity passive cooling as one of the passive solutions for overheating of buildings on the overall thermal response of building envelope systems. Specifically, a variety of multi-layer external walls during realistic summer time conditions of Central European climate were considered. For this purpose, a finite element method was used to simulate the non-stationary thermal response of several heavy weight and light weight external wall constructions. The results have shown that indoor air change intensity as well as internal heat gains have a significant impact on heat flow through the building envelope. Clear difference in thermal behaviour was detected between light weight and heavy weight envelope systems, as a consequence of different thermal mass and thermal insulation position. While the results of the conducted study represent guidelines to architects, designers, investors and other stakeholders in building industry, the growing popularity of light weight constructions, especially in residential buildings, dictates further research of building envelope configurations and passive cooling system impact on the thermal response of constructions.
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