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PurposeThe aim is to holistically assess the environmental performance of windows and analyse how their design and characteristics contribute to the overall performance of the building/space. This study focuses on the performance of windows in patient rooms hosting less mobile people.Design/methodology/approachThis study investigates the life cycle environmental impacts of different glazing types, window frames and fire safety doors at the product level. This article also presents a building-integrated environmental analysis of patient rooms that considers the multiple functionalities of windows by incorporating dynamic energy analysis, comfort and daylighting performance with a life cycle assessment (LCA) study.FindingsThe results indicate that the amount of flat glass is the main contributor to the environmental impacts of the glazing units. As for the patient rooms, global warming shows the most significant contribution to the environmental costs, followed by human toxicity, particulate matter formation and eutrophication. The key drivers for these impacts are production processes and operational energy use. This study highlights the significance of evaluating a wide range of criteria for assessing the performance of windows.Originality/valueAn integrated assessment approach is used to investigate the influence of windows on environmental performance by considering the link between window/design parameters and their effects on energy use/costs, daylighting, comfort and environmental impacts. The embodied impacts of different building elements and the influence of various design parameters on environmental performance are assessed and compared. The environmental costs are expressed as an external environmental cost (euro).

Abstract The building sector is well known as one of the significant contributors to climate change. The use of materials and energy are important drivers, both during construction and the whole life cycle. This study is part of a research to improve the Belgian national approach of life cycle environmental assessment for buildings. The current approach focusses mainly on material use, and the operational energy is estimated via the equivalent degree day method assuming a fixed value of 1200 equivalent heating degree days per year. This paper extends this widespread degree day approach to improve its accuracy by including the effect of various parameters (climate, building characteristics, obstructions by the environment, occupant behaviour). Step by step user-friendly input and graphical feedback is moreover considered necessary for designers and has been added. The annual heating energy estimated by our proposed semi-dynamic model has been validated by dynamic energy simulations using EnergyPlus of 8000 randomly generated cases. Both results have been plotted in a 2D graph. The slope of the linear regression through the origin is 0.8955, and the R-square value is 0.9058. Based on this comparison, it is concluded that the semi-dynamic model, with simplified input and fast results, has sufficient accuracy for the first design phases compared to the dynamic model.

Abstract During the master planning of neighbourhoods, design decisions related to the urban layout and typology affect the building form and availability of solar radiation considerably. The influence of those decisions on the energy demand for heating is often neglected however because appropriate energy simulation tools are lacking. This paper proposes a simple and accurate design tool to assess the solar gains and heating energy demand in buildings during the master planning phase of neighbourhoods. Detailed information on building geometry, constituting building elements and solar obstructions, is extracted from a 3D neighbourhood model using a plugin implemented in the modelling software SketchUp. This information is used to assess the heating energy demand of the buildings in the neighbourhood based on the dynamic Equivalent Heating Degree Day (dEHDD) method. Furthermore, the associated financial and environmental impacts are calculated based on an integrated life cycle approach, combining Life Cycle Costing (LCC) and Environmental Life Cycle Assessment (E-LCA) respectively. The design tool proposed is implemented for the Belgian context and used to analyse a number of schematic residential neighbourhood models with diverse built densities. The analysis reveals substantial differences in heating energy demand, life cycle financial and environmental costs. Neighbourhoods with a high built density and compact building types have a lower heating energy demand with potential reductions of up to 40% compared to neighbourhoods with a low built density and detached building types.

Abstract In the overall aim to build more sustainably, the energy performance of buildings has received a lot of attention in the past decade. In consequence, the embodied impact of buildings has become relatively more important. As the load-bearing structure is responsible for a large share of this embodied impact, it is important to design it in such a way that its environmental impact is as low as possible. Unfortunately, the best construction materials in terms of environmental impact are not necessarily the cheapest. Reducing the environmental impact of the design may therefore lead to a higher financial cost, which may exceed the available budget. In such cases, hybrid structures, consisting of two (or more) different materials, might offer a solution, as they allow the designer to finetune the trade-off between environmental impact and financial cost. In this paper, we present a method to determine the best design of hybrid steel/timber structures in terms of environmental impact within the limits of the available budget. The method is based on the solution of a multi-objective structural design optimization problem involving environmental life cycle assessment and life cycle costing. It is applied to two test cases: a statically determinate and a statically indeterminate truss structure. The structures are optimized for three different design scenarios and typical load cases. This results in a Pareto front in the environmental and financial life cycle cost spectrum, allowing the designer to select the most appropriate solution, given the available budget. The results show that, depending on the design conditions, hybrid steel/timber structures are in some cases Pareto-optimal.