Renovation Measures Research Articles

Effect of a one-dimensional approach in LCA on the environmental life cycle impact of buildings: Multi-family case study in Flanders

The environmental impact of buildings is commonly quantified through life cycle assessment (LCA). Because of practical constraints (e.g. data limitations, timing, complexity), various simplifications are often made. However, the impact of certain simplifications is not clear. Due to the particular geometry of a building, the execution of renovation measures typically entails environmental impacts due to material and energy use at building envelope interfaces which are not considered in simplified LCAs. Hence, this paper examines the effect of a one-dimensional approach as simplification strategy on the environmental impact regarding material use and operational energy use for different renovation scenarios applied to a residential high-rise building. A simplified LCA is therefore compared with a detailed LCA that considers the real building design. First, the effect of linearly scaling the environmental impact based on a one square meter approach is confronted with the real building complexity. Then, the impact of neglecting thermal bridges on the operational energy use is analysed. Finally, both results are combined to evaluate the overall effect on the environmental life cycle impact. The simplifications entail an underestimation of the environmental material use, operational energy use and life cycle impact of 6–49%, 10–36% and 10–30%, respectively. The underestimation of the life cycle impact highly correlates with the operational energy use because of the significant contribution of the operational energy use to the environmental life cycle impact, namely 81–99%. As a result, the effect of simplifications concerning material use on the total life cycle impact is found to be negligible.

Effect of energy renovation and occupants' activities on airborne particle concentrations in Swedish rental apartments

Exposure to airborne particles causes detrimental health effects, hence their assessment in indoor environments, where people spend most of the time, is important. The influence of energy renovation and occupants' activities on airborne particle concentrations was assessed in seven occupied Swedish residences. Ultrafine particle (UFP, <100 nm) number concentrations, PM2.5 (<2.5 μm) and black carbon (BC, <900 nm) mass concentrations were simultaneously measured inside and outside before, after renovation, and during follow-up.The average indoor UFP number concentrations increased from 6200 (±4070) cm-3 before renovation to 12,700 (±6040) cm-3 during the follow up, as the number of indoor activities doubled. Indoor UFP number concentrations depended mainly on frequency and type of occupants' activities in studied residences (e.g., cooking, candle burning). The average indoor PM2.5 concentration decreased from 8.6 (±5.8) μg m-3 before renovation to 2.5 (±1.3) μg m-3 during follow up, as the activities that generated PM2.5 decreased, and infiltration of outdoor particles could have been decreased due to renovation measures. However, the indication of infiltration decrease during the follow up, assessed on the basis of indoor to outdoor ratios during non-activity times (with no influence of occupants' activities), was not observed after the renovation and should be treated with caution. In this study indoor PM2.5 and BC were influenced by activities and outdoor concentrations. Reduction of exposure to indoor UFP, might be obtained by optimization of kitchen exhaust flows. An improved design of supply air inlets in mechanical exhaust ventilation systems may reduce PM2.5 infiltration.Occupants' logbook records, needed for identification of sources contributing to particle exposure, proved useful but not always accurate compared to technical measurements of activities and UFP concentrations. Development of simple and reliable activity detection systems is needed to complement logbooks and allow accurate assessment of source contribution to particle exposure in homes and associated health effects.

Using energy saving deficit distributions to assess calculated, deemed and metered electricity savings estimations

Energy efficiency programme monitoring is often based on ex-ante saving estimations. These estimations lack standardization, are prone to parameter errors, and neglect rebound effects. Moreover, a comparison with ex-post estimations is not systematically done. This paper proposes a simple methodology to assess ex-ante against ex-post estimations, using the distribution of the energy savings deficit, i.e. the normalized difference between reported and metered savings. This methodology is applied to a dataset of lighting renovation measures to first assess calculated savings against utility meter data. The mean energy savings deficit amounts to 39% for measures in small to medium enterprises and to 28% in common areas of buildings. Further analysis shows that this overestimation arises from both significant calculation errors and rebound effects. These analysis and findings are the first of their kind for these sectors. The methodology is further used to assess deemed savings approaches. The results show that coefficients based on time-of-use and the type of replaced technology provide a precision comparable to calculated savings. Further limitations of ex-ante quantitative monitoring are identified based on empirical observations of a utility-driven programme. This suggests that, instead of current practices, quantitative monitoring should focus on ex-post analysis of meter data. This would free up resources for a more qualitative follow-up of measure impacts to better inform programme and policy design.

Potentials for increasing resident wellbeing in energy renovation of multi-family social housing

The paper explores potentials for increasing residents' wellbeing in multi-family social housing (MSH) undergoing energy renovation. The renovation measures needed to reach national and global climate goals are often not financially feasible when viewed in isolation. Therefore, it is relevant to identify potentials for added value, which can justify more extensive measures. This paper is based on the hypothesis that every renovation project holds potentials for added value in terms of increased resident wellbeing. Further, that it is crucial to extend current understandings of wellbeing beyond single, quantitative wellbeing parameters in order to promote more holistic, long-term sustainable renovation solutions. The paper sheds light on potentials for increased resident wellbeing based on an analysis of residents’ experience and satisfaction with gestures in the existing built environment and comparing these findings to their perceived health. The analysis is based on data collected through a mixed-methods approach in three MSH areas facing extensive renovation. The findings demonstrate and exemplify that energy renovation measures may influence a number of interrelated physiological, mental and social wellbeing aspects across scales. As such, the paper contributes with new insights, which can help promote previously neglected aspects of resident wellbeing in future energy renovation design processes.

BIM-based green building evaluation and optimization: A case study

Green building has drawn worldwide attention due to the adverse impact of construction on the environment. This research presents a Building Information Modeling (BIM) based evaluation system for the performance assessment of green buildings. Combining BIM technology with green building analysis, the proposed approach can fully utilize the advantages of the BIM model and quickly conduct green building evaluation. A green building evaluation framework is constructed, which evaluates the green building performance from five aspects, i.e., the main building, the building envelope, the heating, ventilation and air conditioning (HVAC), the lighting and equipment, and extra points. A case study is performed to test the applicability and effectiveness of the proposed approach. Important findings are: (1) The performance of the target green building is determined as 0.87 (i.e., a fairly poor level), but it could be upgraded to 1.32 (i.e., a good level) with the consideration of extra points for the green building evaluation (2) Building renovation measures (i.e., improving the building envelop, HVAC, and lighting and equipment); could improve the performance of the green building by 31.5% on average. A synergetic impact exists among these renovation measures, where the impact of renovating all three aspects is greater than simply the sum of taking three individual measures; (3) Optimization of the green building performance could not only reduce the energy consumption but also create a more comfortable environment for the occupants, where severe conditions could be greatly reduced. The novelty of this research lies in (a) presenting a BIM-based model that is able to effectively perform the green building evaluation and optimization in a wide range and also incorporate the regional features as needed; (b) proposing a novel grading rule that makes influential factors under different standards measurable in a more intuitive manner.

Monitoring the Prestressed Rods in the Basel Border Bridge Maintenance Project: Data Analysis during the Passage of Trucks.

More than 40 years ago, the expansion joints on the Basel border bridge were constructed using corbels and dapped ends. The consoles had to be reinforced as part of the renovation measures due to damage caused by chloride entry and due to the increased loads. Diagonal rods, which were prestressed, were used. Fiber-optic sensors were additionally installed to these highly stressed rods in order to measure the strains and temperatures. This now makes it possible to measure the actual strains in the strengthening of the corbel, estimate fatigue loads, and set up a warning system in case of overstressing. This article presents the design of the measurement system and the analysis of the data. Furthermore, the reference measurements that can establish the relationship between the measured strains and the loads passed over are presented.

What is the optimal robust environmental and cost-effective solution for building renovation? Not the usual one

Buildings are responsible for a large share of CO2 emissions in the world. Building renovation is crucial to decrease the environmental impact and meet the United Nations climate action goals. However, due to buildings’ long service lives, there are many uncertainties that might cause a deviation in the results of a predicted retrofit outcome. In this paper, we determine climate-friendly and cost-effective renovation scenarios for two typical buildings with low and high energy performance in Switzerland using a methodology of robust optmization. First, we create an integrated model for life cycle assessment (LCA) and life cycle cost analysis (LCCA). Second, we define possible renovation measures and possible levels of renovation. Third, we identify and describe the uncertain parameters related to the production, replacement and dismantling of building elements as well as the operational energy use in LCCA and LCA. Afterwards, we carry out a robust multi-objective optimization to identify optimal renovation solutions. The results show that the replacement of the heating system in the building retrofit process is crucial to decrease the environmental impact. They also show that for a building with already good energy performance, the investments are not paid off by the operational savings. The optimal solution for the building with low energy performance includes the building envelope renovation in combination with the heating system replacement. For both buildings, the optimal robust cost-effective and climate-friendly solution is different from the deep renovation practice promoted to decrease the energy consumption of a building.

Business Model Development for Temporary Home Renovation Consultancy Centres: Experiences from European Pop-Ups

Local authorities (LAs) play an essential role in diffusing home energy renovation measures. However, there are rare business models developed for local authority actions. This paper aims to develop a critical review of the way that local authorities developed business models for pop-up centres where consultants can encourage home energy renovation measures. From 2017 to 2021, participatory research was conducted in collaboration with seven LAs from the UK, France, Belgium, and the Netherlands. Although local authorities could use business model approaches for the development of pop-up home renovation consultancy centres, we noticed that LAs could not apply specific strategies to fit various customer segment groups. Therefore, a traditional business model needs to be investigated further for local authority activities.

Environmental Physical and Perceived Quality in Hospice.

This study presents the application of post-occupancy evaluations (POEs) methodologies to facilities for palliative-hospice care, in order to directly assess the physical-spatial qualities better suited for the specific psychological needs of "fragile" users and to ensure better architectural quality in new projects and in renovation measures. In international literature, there are few studies concerning the application of POEs to hospice, assessing the impact of individual environmental factors on users' psychoemotional reactions. The set of elements that patients and their families perceive as important, defining the architectural quality of a hospice, has not been sufficiently investigated yet. Therefore, a POE was performed on a sample of hospice in Italy, by preparing a self-filled questionnaire addressing patients and relatives. Indicators of perceived physical-spatial humanization, which were validated for hospital facilities (perceived hospital environment quality indicators), were used for the assessment then implemented and harmonized in relation to hospice facilities features. The study revealed the indicators of architectural quality most valued by users, whose reliability was then verified, along with their average quality, by highlighting recurring shortcomings. The global quality was found to be generally high. Below-average scores were found for indicators on usability, acoustic comfort of outdoors, visual and acoustic comfort of shared indoor spaces, and artificial lighting in the recovery room. The study generated new knowledge on hospice and confirmed the efficacy of POEs as a tool both for purchasers and designers. Indeed, the first results of this study allow to recalibrate building programs, revisiting layouts, and elaborating appropriate technical solutions.

Issues and challenges of implementing comprehensive renovation at aged communities: A case study of residents’ survey

The comprehensive renovation for aged communities is an important part of improving the building function, meeting the residential need, and realizing the organic renewal of the cities. Although there are various renovation techniques, implementing comprehensive renovation at aged communities is still a major challenge due to low willingness to renovation from the residents. Therefore, this paper carried out a questionnaire to study the issues of implementing comprehensive renovation at aged communities to survey residents' willingness. The resident’s indoor thermal sensation, willingness to accept renovation measures and investment willingness were analyzed using the survey data. Potential factors affecting residents' willingness to accept renovation measures were discussed. The results showed that residents were willing to accept basic renovation measures but had low willingness to accept the quality improvement and renewable energy measures. Socio-economic variables, residential characteristics and indoor thermal sensation affected residents’ willingness to accept comprehensive renovation. Tailored renovation schemes based on the existing problems of communities and residents’ willingness could greatly promote implementation of comprehensive renovation.

Low-energy cooling and ventilation refurbishments for buildings in a Mediterranean climate

ABSTRACT In view of the ageing domestic building stock and increasing reliance on fossil fuels for cooling and ventilation of buildings, there is an urgent need for improved design knowledge and sustainable measures such as natural ventilation and passive cooling to mitigate climate change and future proof the built environment. This paper forms an appraisal of a range of low-energy refurbishment measures, i.e. building design alterations and passive systems, which were employed and evaluated in an apartment building in Greece. The applicability of these in domestic buildings in hot climates is assessed and their design implications evaluated. Implementation of wind-catchers, dynamic façades, and evaporative cooling had the highest ventilation and cooling potential, while improvements of the interior layout to allow for new airflow paths could provide further cooling to spaces and solutions to safety.

The role of electricity mix and production efficiency improvements on greenhouse gas (GHG) emissions of building components and future refurbishment measures

PurposeAn estimation of the environmental impact of buildings by means of a life cycle assessment (LCA) raises uncertainty related to the parameters that are subject to major changes over longer time spans. The main aim of the present study is to evaluate the influence of modifications in the electricity mix and the production efficiency in the chosen reference year on the embodied impacts (i.e., greenhouse gas (GHG) emissions) of building materials and components and the possible impact of this on future refurbishment measures.MethodsA new LCA methodological approach was developed and implemented that can have a significant impact on the way in which existing buildings are assessed at the end of their service lives. The electricity mixes of different reference years were collected and assessed, and the main datasets and sub-datasets were modified according to the predefined substitution criteria. The influence of the electricity-mix modification and production efficiency were illustrated on a selected existing reference building, built in 1970. The relative contribution of the electricity mix to the embodied impact of the production phase was calculated for four different electricity mixes, with this comprising the electricity mix from 1970, the current electricity mix and two possible future electricity-mix scenarios for 2050. The residual value of the building was also estimated.Results and discussionIn the case presented, the relative share of the electricity mix GHG emission towards the total value was as high as 20% for separate building components. If this electricity mix is replaced with an electricity mix having greater environmental emissions, the relative contribution of the electricity mix to the total emissions can be even higher. When, by contrast, the modified electricity mix is almost decarbonized, the relative contribution to the total emissions may well be reduced to a point where it becomes negligible. The modification of the electricity mix can also influence the residual value of a building. In the observed case, the differences due to different electricity mixes were in the range of 10%.ConclusionsIt was found that those parameters that are subject to a major change during the reference service period of the building should be treated dynamically in order to obtain reliable results. Future research is foreseen to provide additional knowledge concerning the influence of dynamic parameters on both the use phase and the end-of-life phase of buildings, and these findings will also be important when planning future refurbishment measures.

Novel Methodology toward Nearly Zero Energy Building (NZEB) Renovation: Cost-Effective Balance Approach as a Pre-Step to Cost-Optimal Life Cycle Cost Assessment

Reaching environmental targets set by the European Union (EU) requires a constant renovation of the existing building stock to nearly Zero Energy Buildings (NZEB) in a cost-optimal manner. Studies show that the renovation rate of the existing building stock is more than two times less than what is necessary to reach the targets. Furthermore, the majority of performed renovations across the EU reach just a small amount of energy savings, whereas NZEB renovations are rarely achieved. This paper proposes a methodology for the evaluation of renovation measures, aiming to provide decision support related to the selection of what to renovate and to what extent. The proposed method is rooted in the well-established cost-optimal methodology, yet it suggests a pre-step to package evaluation. This is done by means of a simplified cost-effective parameter (CEP), linking cost, lifetime, and energy savings. The methodology is demonstrated using a case study building in Denmark. The results show that the CEP provides good grounds for the compilation of single actions to packages. Further developments could focus on the sensitivity of the model inputs and integration of additional evaluation parameters to cost, such as environmental, architectural, comfort, risk, etc.

Experimental analysis of a prototype for a thermochromic Trombe wall

ABSTRACT Ambitious and innovative refurbishment measures will be required to meet the European Union’s goals for limiting building energy consumption. Envelope efficiency can be enhanced, for instance, with new materials and improved passive techniques. Trombe walls (TWs), one such technique, reduce heating demand in winter, although they cause overheating in warm climates. That drawback may be corrected with thermal-optically reversible materials. In this study, a thermochromic mortar was applied to a prototype TW to reduce solar absorption in summer without affecting its wintertime efficacy. Further to field measurements, the maximum surface temperature reached on the wall’s thermochromic cladding (TCC) was 32°C in winter and 44.7°C in summer. The indoor cold weather temperature in the module ranged from 7.9°C to 16.5°C for a mean of 11°C, compared to 25.1°C to 32.2°C with a mean of 28.9°C in warm weather. Ventilating the air gap at 60–200 ach prevented the cladding from fading to nearly colourless in winter. In light of the improved thermal transfer performance delivered, the TTW proposed can profitably be used for energy refurbishment in existing buildings.

Positive Energy District: A Model for Historic Districts to Address Energy Poverty

The Positive Energy District (PED) concept has been pointed out as key for cities' energy system transformation toward carbon neutrality. The PED may be defined as an energy-efficient and flexible urban area with net-zero energy import and greenhouse gas emissions, aiming toward annual local surplus of renewable energy. Most of the studies and practical experiences about PEDs are based on newly built districts, where the planning and integration of innovative solutions are less complex and more cost-effective. However, to achieve Europe Union's 2050 carbon-neutral ambition, we argue that the transformation of the settled districts is essential, including historic districts, which present common challenges across European cities, such as degraded dwellings, low-income families, and gentrification processes due to massive tourism flows. This paper aims to discuss how the PED model can be an opportunity for historic districts to reduce their emissions and mitigate energy poverty. The historic district of Alfama, in the city of Lisbon (Portugal), is used as a case study to show the potential of energy renovation measures and solar PV production in households, cornerstones of a PED. The annual energy needs potential reduction due to building retrofit is 84 and 19% for space heating and cooling, respectively, while the integration of building-integrated PV technologies in rooftops and windows potentially generates up to 60 GWh/year. At the district scale, these two components of the PED concept could require an investment of 60M€ to 81M€ depending on the PV technologies in the rooftops, a sensitive aspect in historical districts. Unlike other mechanisms to tackle energy poverty, like the social tariffs, the adoption of structural measures like building energy efficiency retrofit and renewable energy integration will contribute to solve the energy poverty problem, which is significant in Alfama, in both the winter and summer. The highlighted investments require an innovative financial scheme to support not only buildings' owners but also tenants, as these are among the most vulnerable to energy poverty. However, the social benefits of that investment, on the health system, air quality, climate resilience, labor productivity, and social integration, would be invaluable.

Energy renovation strategies for office buildings using direct ground cooling systems

Direct ground cooling systems (DGCS) can provide comfort cooling to buildings without the use of any refrigeration-based cooling methods. DGCS is an emerging technology, commonly used for new office buildings in cold climates. This study aims to evaluate the energy-saving possibilities of a DGCS compared to a conventional chiller system for an existing office building. A typical Swedish office building with a chiller-based cooling system and in need of an energy renovation is taken as a reference case. Various possible renovation measures are applied on the building and to the cooling system, and the results are evaluated in terms of borehole design and building energy demand. The results show that applying the DGCS substantially reduces the building’s purchased energy, as chiller electricity demand is eliminated. In addition, implementing the renovation measures to reduce the thermal demand of the building could further reduce purchased energy. The results suggest implementing the DGCS after performing the renovation measures. This may lead to a considerable reduction in the required borehole length and hence in the drilling costs. Results from this study provide useful inputs for designing boreholes in ground-coupled systems for new and existing office buildings.

Integrated Performance Optimization of Higher Education Buildings Using Low-Energy Renovation Process and User Engagement

Building performance improvement through low-energy renovation traditionally involves building performance diagnostics of the existing building, technology evaluation, selection and implementation. Effective building performance diagnostics, post-retrofit assessment and user engagement are essential to deliver performance as well as achieving socio-economic and environmental benefits at every stage of the renovation project life cycle. User’s views are often ignored when renovating a building, causing sub-optimal energy performance, user comfort and wellbeing. This paper seeks to critically evaluate the low-energy renovation process and the role of user and stakeholder engagement in the strategic implementation of low-energy retrofit technologies for performance improvement of higher education buildings. The research focuses on renovation methodology, innovative materials/systems and end-user engagement throughout the renovation project phases (pre-renovation, the renovation process and post renovation). A mixed research method was adopted, which includes building performance modelling, monitoring and user evaluation questionnaires pre and post-renovation. The research is part of European Union (EU)-funded project, targeting 50% reduction in energy consumption using innovative materials and technologies in existing public buildings. The surveys allow comparative analysis of comfort levels and user satisfaction as an indicator of the efficacy of renovation measures. A new renovation process and user engagement framework was developed. The findings suggest that there is a direct relationship between retrofit intervention, improving energy performance of low-carbon buildings and the comfort of occupants. The technologies and strategies also appear to have different impacts on user satisfaction.

A novel spatial based approach for estimation of space heating demand saving potential and CO2 emissions reduction in urban areas

Space heating accounts for the most significant share of final energy demand in buildings in colder climatic regions contributing to greenhouse gas emission. In addition, there is a lack of data available to assess spatially, the potential of space heating demand reduction in different buildings when considering typical building refurbishment measures. Hence, in this paper, a robust information socket for urban building stock is developed to assess the impact of energy efficiency measures on space heating demand savings and CO2 emission reduction potential in the existing buildings based on a Geographical Information System tool. The model considers the topology and thermal performance of different building categories; houses with and without thermal insulation, apartments, commercial, public, office, and industrial buildings. Three scenarios, a reference and two additional scenarios using Prishtina city as a case study, have been created for standard (scenario 1), and advanced energy efficiency (scenario 2) measures based on the government’s proposed policies. The findings show that space heat demand saving potential for scenario 1 and 2 in comparison to the reference scenario was 50% and 68.5% respectively. Moreover, the CO2 emissions are reduced significantly from 502.3 mil kgCO2/year in reference scenario to 249.8 mil kgCO2/year for scenario 1 and 158.7 mil kgCO2/year in scenario 2 respectively.

New Opportunities for Increasing the Renovation Rate of Buildings

Abstract The paper focuses on the long-standing problem of too low renovation rates of existing buildings and on practice-oriented solutions. The European Commission has set the goal of at least doubling the renovation quota with “The European Green Deal” and published the “Strategy for a Renovation Wave for Europe - greening our buildings, creating jobs, improving lives” on 14 October 2020. As in previous years, technical specifications have been defined even more strictly and limit values for energy consumption have been further reduced with the aim to reduce CO2 emissions. The high quality of the renovation measures is ensured within the European Union and its member states. However, this has not yet been the case in relation to the quantity of implemented renovation projects. The thesis investigates which factors were neglected or were not taken into consideration sufficiently in the past, and, because of that, countries like Austria could not achieve their goals with regard to the renovation rates. This is done by identifying, selecting and verifying both specific and potential conflicting goals. On the basis of the description and analysis of the background to these potential conflicts, the actual obstacles are identified and approaches to their solutions are defined. The formulated approaches should form the basis for future in-depth discussion and further development of specific detailed solutions. The implementation of these results in a comprehensive package with technical regulations such as the “Renovation Wave for Europe” and “The European Green Deal”, opens up new opportunities for achieving the set goals. An increase in the renovation rate of existing buildings is the quantitatively measurable outcome.

Optimal Renovation Strategies through Life-Cycle Analysis in a Pilot Building Located in a Mild Mediterranean Climate

The 2030 climate and energy framework includes EU-wide targets and policy objectives for the period 2021–2030 of (1) at least 55% cuts in greenhouse gas emissions (from 1990 levels); (2) at least 32% share for renewable energy; and (3) at least 32.5% improvement in energy efficiency. In this context, the methodology of the cost-optimal level from the life-cycle cost approach has been applied to calculate the cost of renovating the existing building stock in Europe. The aim of this research is to analyze a pilot building using the cost-optimal methodology to determine the renovation measures that lead to the lowest life-cycle cost during the estimated economic life of the building. The case under study is an apartment building located in a mild Mediterranean climate (Castellon, SP). A package of 12 optimal solutions has been obtained to show the importance of the choice of the elements and systems for renovating building envelopes and how energy and economic aspects influence this choice. Simulations have shown that these packages of optimal solutions (different configurations for the building envelope, thermal bridges, airtightness and ventilation, and domestic hot water production systems) can provide savings in the primary energy consumption of up to 60%.