Karen Allacker

KU Leuven | ku leuven · Faculty of Engineering Science

In order to achieve the necessary reduction of greenhouse gas (GHG) emissions and decarbonization of building construction and operation, both high- and low-tech building design strategies are promoted. Amongst particularly promising strategies are the deployment of energy efficiency measures, for reducing operational energy use and related impacts...

The focus in reducing environmental impacts of buildings is shifting from the operational stage to the full life cycle, with particular attention to embodied greenhouse gas (GHG) emissions of construction materials. The application of bio-based construction materials is promoted for potentially reducing material-related embodied GHG and even enabli...

Strict energy performance requirements have reduced the building's operational energy use and related environmental impact in the past decades. Consequently, the embodied impacts of buildings gained importance, and hence focussing on the life cycle impacts has become essential to further reduce the environmental impact of buildings. Life cycle asse...

The focus in reducing environmental impacts of buildings is shifting from the operational stage to the full life cycle, with particular attention to embodied greenhouse gas (GHG) emissions of construction materials. The application of bio-based construction materials is promoted for potentially reducing material-related embodied GHG and even enabli...

In order to achieve the necessary reduction of greenhouse gas (GHG) emissions and decarbonization of building construction and operation, both high- and low-tech building design strategies are promoted. Amongst particularly promising strategies are the deployment of energy efficiency measures, for reducing operational energy use and related impacts...

PURPOSE The purpose of this research is to estimate the renovation potential of a city’s building stock and evaluate the environmental impact reduction and greenhouse gas emission reduction realized by clustered renovation. These reductions are compared to the climate goals for 2050 by the city of Leuven, i.e., 81% reduction in CO2-eq. compared to...

Buildings’ construction and operation are major contributors to global greenhouse gas (GHG) emissions, and the substantial reduction of GHG emissions across their full life cycle is required to enable meeting international climate targets. For effective climate change mitigation - as recent studies have shown - a special focus has to be put on lowe...

Over recent years Belgium has made meaningful effort in adopting Life Cycle Assessment (LCA) in building practice to improve building environmental performance. Today, architects can compare the environmental performance of different building designs with an online calculation tool that incorporates the national LCA method. However, they are still...

In the context of the Renovation Wave, clustered renovations might be a potential approach to increase the renovation rate. In this paper a new methodology is presented to cluster buildings based on their renovation potential in view of grouped renovation actions. These clusters are defined at city scale. In this study the city of Leuven (Belgium)...

This study investigates the influence of window system configurations on the energy use/cost, access to daylight and view, visual comfort and environmental performance in a one-bed hospital patient room located in a temperate climate. The methodology combines dynamic energy simulations, visual comfort and daylight analysis in a life cycle assessmen...

Currently, a life cycle assessment is mostly used in a static way to assess the environmental impacts of the energy renovation of buildings. However, various aspects of energy renovation vary in time. This paper reports the development of a framework for a dynamic life cycle assessment and its application to assess the energy renovation of building...

To tackle sustainability, the building sector has to take into account the life cycle impacts of buildings. However, due to the complexity of life cycle assessment (LCA) and life cycle costing (LCC), architects still have a huge hurdle to integrate LCA and LCC in their design processes and even more in the first design stage where the most importan...

The existing building patrimony is responsible for 36% of the global energy use and 37% of the greenhouse gas emissions. It is hence a major challenge to improve its energy performance. According to the Renovation Wave, the average annual renovation rate should be doubled by 2030 up to 3% and deep energy renovations should be encouraged. The Belgia...

Various environmental challenges, particularly the rising severity of the impacts of climate change, require a systematic shift in and decarbonization of the global economy. Due to their high environmental impacts, buildings and construction have a special role in decarbonization. Environmental modelling of building stock dynamics can help policy m...

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 wa...

PurposeSince the Agenda 2030 for Sustainable Development was set, cities are gaining momentum in the sustainability debate as favorable hubs of interventions to implement environmentally friendly policies. What makes a city sustainable is still object of debate though, as standards, frameworks, and methodologies with different goals and scope proli...

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 foc...

Various environmental challenges, particularly the rising severity of the impacts of climate change, require a systematic shift in and decarbonization of the global economy. Due to their high environmental impacts, buildings and construction have a special role in decarbonization. Environmental modelling of building stock dynamics can help policy m...

Net zero energy buildings (NZEBs) are energy efficient buildings that incorporate renewable energy generation systems so as to produce sufficient renewable energy to at least offset the total amount of non-renewable energy used by the building on an annual basis. NZEB technologies have widespread commercial and residential application, but their fe...

This study investigates the influence of glazing characteristics and shading device configuration on energy use and cost, daylighting performance and visual comfort. A typical patient room from a hospital design in Belgium is used as a baseline scenario and different window design alternatives are explored through parametric modeling. Based on the...

The operational energy use of buildings contributes significantly to their environmental impact. In most environmental impact assessments, operational energy consumption and associated impacts are kept unchanged throughout the life cycle of the building. In addition to climate change, the energy mix is also changing over the building life cycle and...

To date, many cities have engaged in efforts to become more sustainable. These efforts often are translated into measures to reduce their greenhouse gas (GHG) emissions, leading to a proliferation of standards and methods. Discrepancies exist between these various accounting approaches in terms of the definition of system boundaries, allocation pro...

Purpose To reduce the environmental impact of the building sector, environmental targets considering the full life cycle of buildings can be supportive. In recent years, various benchmarks based on Life Cycle Assessment (LCA) have been developed as part of regulations, labelling systems, sustainability rating tools and research studies. The objecti...

In 2015, the United Nations chose cities as target of the 11th Sustainable Development Goals, which aims to ‘make cities inclusive, safe, resilient, and sustainable’. However, few quantitative methodologies can tackle the sustainability challenge and support cities in this transition. In order to comply with UN SDGs, the City Environmental Footprin...

The application of the Life Cycle Assessment (LCA) technique to a building requires the collection and organization of a large amount of data over its life cycle. The systematic decomposition method can be used to classify building components, elements and materials, overcome specific difficulties that are encountered when attempting to complete th...

Purpose Life cycle assessment (LCA) is an internationally accepted method to assess the environmental impacts of buildings. A major methodological challenge remains the modelling of the end-of-life stage of buildings and allocation of benefits and burdens between systems. Various approaches are hence applied in practice to date. This paper compares...

The increasing pressure to reduce greenhouse gas emissions from buildings has motivated specialists to develop low-carbon products incorporating bio-based materials. The impact of these materials is often evaluated through life-cycle assessment (LCA), but there is no clear consensus on how to model the biogenic carbon released or absorbed during th...

Target values for creating carbon budgets for buildings are important for developing climate-neutral building stocks. A lack of clarity currently exists for defining carbon budgets for buildings and what constitutes a unit of assessment—particularly the distinction between production- and consumption-based accounting. These different perspectives o...

Wood cascade systems composed of products with long service lives can contribute to carbon storage, resource efficiency and circular economy. The environmental assessment of such multi-output systems is however challenging due to (i) multiple products and recycling steps, and (ii) the distribution of emissions, particularly of biogenic CO2, over lo...

The local outdoor climate and building characteristics influence the energy use of a building to an important extent. To design energy efficient and climate robust buildings, it is important to get insights into the energy demand over the building's service life from the early design phase onwards. This paper presents an overview of the different v...

A renewed interest in bioclimatic strategies for building retrofitting is noticed due to the fact that more than 40% of the total annual world energy consumption is used in buildings. In Chile, existing social housing stock is composed of more than 5,5 million units built with government subsidies. Thermal regulations improvement started in 2000, b...

In Latin America, there is a huge existing housing stock that no meets the minimum requirements for thermal comfort and energy efficiency, built before relatively recent thermal regulations. The scarcity of climate adaptive possibilities and the lack of design in the transitional spaces that these buildings create is identified as a common pattern...

A renewed interest in bioclimatic strategies for building retrofitting is noticed because more than 40% of the total annual world energy consumption is used in buildings. In Chile, the existing social housing stock is composed of more than 5,5 million units built with government subsidies. Thermal regulations improvement started in 2000, requiring...

This dataset is part of the article entitled “Design and experimental study of a low-cost prefab Trombe Wall to improve indoor temperatures in social housing in the Biobío Region in Chile” [1,2]. The dataset represents the outcome of experimental measurements during a 1-year monitoring campaign to assess the performance of an adaptable and low-cost...

In Latin America, there is a huge existing housing stock that no meets the minimum requirements for thermal comfort and energy efficiency, built before relatively recent thermal regulations. The scarcity of climate adaptive possibilities and the lack of design in the transitional spaces that these buildings create is identified as a common pattern...

This dataset is part of the research article entitled “Design and experimental study of a low-cost prefab Trombe Wall to improve indoor temperatures in social housing in the Biobío Region in Chile,” [1] Ref. No.: SE-D-19-03183, submitted to Solar Energy journal. Specifically, the dataset presented is centered in experimental results for a 1-year mo...

Hospitals produce high amounts of emissions due to their continuous operation, high flow of people, and intensive HVAC requirements. In order to reduce the environmental footprint of hospitals, it is crucial to improve energy performance while still maintaining a comfortable indoor environment for the occupants. Also to avoid high environmental bur...

The current renovation rate in Belgium is less than 1% and should be increased to 2, 5% to reach the European targets to reduce the GHG emissions by 2050. There is a need to rapidly increase the renovation rate and at the same time guarantee that these renovations reduce the environmental impact on our planet. In order to define environmental bench...

The operational energy use and related greenhouse gas emissions of buildings are typically influenced by changes during the building service life such as climate change, technological evolution and energy mix evolution. Only few LCA studies consider these temporal variations. This paper investigates how climate change is currently considered in LCA...

The current focus on climate change mitigation is reflected in policy goals to reduce the energy use of buildings. However, buildings are not only responsible for a large share of energy use and corresponding GHG emissions, they moreover require a lot of resources, produce a lot of waste, and emit harmful substances. In this paper, an approach is d...

Recently, Level(s) has been developed by the European Commission as a common EU framework to assess sustainability of buildings with the intention to provide a consistent and comparable framework across national boundaries. It aims at providing a general language for sustainability for buildings and to promote life cycle thinking. This paper descri...

Over their whole life cycle, buildings are responsible for high environmental impacts and require critical financial resources. Decisions in the early design phase have a significant impact on both. This study aims to develop a visual decision support tool for architects in order to integrate an environmental and economic life cycle approach for dw...

The construction sector is facing an important challenge to reduce its resource consumption. A promising strategy is to reduce the need of virgin resources by using the existing building stock as a resource mine. Various insights are needed to enable this. It should be clear how many materials are in the stock, when these will become available and...

To reduce the environmental impact of the building sector, environmental targets should be defined considering the full life cycle of buildings. In recent years various benchmarks based on Life Cycle Assessment (LCA) have been developed as part of regulations, labelling systems and sustainability rating tools. This paper presents the results of a c...

To reach the target of nearly Zero Energy Buildings (nZEBs), considering occupant behaviour is essential from the early design stage. This study proposes a design support tool for architects, which includes flexible and straightforward occupant behaviour modelling from the pre-design stage onwards. The tool uses a semi-dynamic model. The proposed t...

The aim of the PEF4Buildings project, commissioned by the European Commission, was to assess if the Product Environmental Footprint (PEF) method and related guidance documents developed in the framework of the Environmental Footprint pilot test phase are applicable at the building level. The project has been coordinated by VITO with TU Graz and KU...

Purpose From 2010, more than half of human beings live in cities and global urbanization is growing at a fast pace. This leads to threats for the associated potential environmental burdens, but also to opportunities for cities to gain a leading role as hubs of interventions in favor of sustainability. The Life Cycle Thinking approach is suitable to...

With the increasing awareness of sustainable design “operational energy use”, “life cycle environmental impact” and “comfort” are becoming key considerations for design decisions. These three aspects are usually not explored in an integrated way in the early design stage. During this stage however, most far-reaching design decisions are made and th...

As the budget of social housing companies is limited, reducing the energy use of their housing stock to be compliant with current standards and actions plans is an important challenge. Currently social housing companies in Flanders often prefer replacing the heating system to insulating the building envelope due to the lower investment cost and eas...

Purpose Energy consumption of buildings is one of the major drivers of environmental impacts. Life cycle assessment (LCA) may support the assessment of burdens and benefits associated to eco-innovations aiming at reducing these environmental impacts. Energy efficiency policies however typically focus on the meso- or macro-scale, while interventions...

With the aim of moving towards a more sustainable society, hospital buildings are challenged to decrease their environmental impact while continuing to offer affordable and qualitative medical care. The aim of this paper was to gain insight into the main drivers of the environmental impacts and costs of healthcare facilities, and to identify method...

As buildings have a relatively long life span, it is important to consider climate change in energy performance modelling. Good quality weather data are needed to obtain accurate results. This chapter discusses widely used methods to predict future weather data (dynamical downscaling, stochastic weather generators and morphing) and provides an over...

Urban planning decisions related to the urban form, built density and neighbourhood location may affect the sustainability of neighbourhoods to an important extent. This chapter investigates the influence of urban planning on the financial and environmental impact of neighbourhoods. A number of schematic neighbourhood models with various layouts an...

Due to the growing population, the revived trend of living in urban areas and the scarcity of building plots, the idea of vertically extending existing residential buildings is gaining popularity in Belgium. Timber frame constructions are appropriate due to their light weight and lack of point loads. This article aims to assess (1) the potential en...

Concerns about the sustainability of healthcare facilities have been raised over the past decennia, reflected in a proliferation of certification schemes such as BREEAM, LEED and DGNB. Although these schemes are easy to implement, the subjective benchmarking on which the sustainability assessment is based, leaves doubts whether the use of these sch...

Globally, the building sector is responsible for more than 40% of energy use and it contributes approximately 30% of the global Greenhouse Gas (GHG) emissions. This high contribution stimulates research and policies to reduce the operational energy use and related GHG emissions of buildings. However, the environmental impacts of buildings can exten...

The PEF4Buildings project is commissioned by the European Commission and is carried out by the Flemish Institute for Technological Research (VITO), KU Leuven and TU Graz. The aim of the project is to test the applicability of the PEF method Guide (Commission Recommendation 179/2013 on The use of common methods to measure and communicate the life cy...

Facades are a crucial interface between exterior and interior conditions and greatly influence the architectural quality of buildings. Glass plays an important role in the building envelope by providing daylight, views and ventilation and hence can contribute significantly to indoor environmental quality and impact occupants’ comfort and well-being...

The chapter explains what Sustainable Consumption and Production (SCP) is about, why it is about taking a life cycle approach and shows that SCP-related policies have been developed at the intergovernmental level and in different regions of the world. A key element at the international level is the 10-Year Framework of Programmes on SCP adopted in...

Hospital buildings produce high amounts of emissions and waste. Strategies are needed to reduce their impacts while still providing quality care for patients. As patient rooms occupy the largest space of hospital buildings and windows play a major role in both energy loads and quality of the indoor environment, analysing their role on the environme...

In 2015, the United Nations chose cities as target of the 11th Sustainable Development Goals, which aim to “make cities inclusive, safe, resilient, and sustainable”. Indeed, the increasing urbanization worldwide poses serious threats for the related environmental burdens, but also opportunities for cities to be a driver for change and privileged pl...

Urban sprawl and the increase of the built-up area have a major impact on land use. Buildings are responsible for two types of land use interventions: primary land use, i.e. the building footprint and secondary land use, associated with the resource extraction, production, transport and end-of-life treatment of construction products. However the en...

Cities are complex entities which are constantly evolving, they are responsible for the largest share of most environmental impacts, but provide also major opportunities for improvement. Nevertheless, holistic methodologies to evaluate the environmental footprint of cities are still lacking at the urban scale level. Currently, carbon footprint and...