Recently, there has been an increase in apartments with a large number of inhabitants, i.e., high residential density. This is partly due to a housing shortage in general but also increased migration, particularly in suburbs of major cities. This paper specifies issues that might be caused by high residential density by investigating the technical parameters influenced in Swedish apartments that are likely to have high residential density. Interviews with 11 employees at housing companies were conducted to identify issues that might be caused by high residential density. Furthermore, simulations were conducted based on extreme conditions described in the interviews to determine the impact on the energy use, indoor environmental quality, and moisture loads. In addition, the impact of measures to mitigate the identified issues was determined. Measures such as demand-controlled ventilation, increase of a constant ventilation rate, and moisture buffering are shown to reduce the risk for thermal discomfort, mold growth, and diminished indoor air quality; while still achieving a lower energy use than in a normally occupied apartment. The results of this study can be used by authorities to formulate incentives and/or recommendations for housing owners to implement measures to ensure good indoor environmental quality for all, irrespective of residential density conditions.

During the last few years, there has been an increased number of overcrowded apartments, due to increased migration but also housing shortage in general, particularly in the suburbs to major cities. The question is how the indoor environment in these apartments is affected by the high number of persons and how the problems related to high residential density can be overcome. This paper aims to specify the problem by investigating and analysing the technical parameters influenced by residential density in Swedish apartments built between 1965-1974. To map the situation, 11 interviews with employees at housing companies were conducted. Based on extreme conditions described in the interviews, simulations of the indoor climate and moisture risks at some vulnerable parts of constructions were made. Simulations were focused on moisture loads and CO2 concentrations as functions of residential density and ventilation rate. Finally, measures to combat problems associated to overcrowding are suggested. The aim is that the results should be used by authorities to formulate incentives and/or recommendations for housing companies to take actions to ensure a good indoor environment for all, irrespective of residential density conditions. © The Authors.

In the context of the circular economy, there is an urgent need for transformation into circular material flows by avoiding waste, reducing extraction of virgin raw materials, and extending product life cycles. Within the construction and real estate industry, the reuse of building materials stands out as a critical strategy for value retention. The objective of this paper is to localise the forefront of the practical implementation of reused materials within the Swedish construction and real estate industry. To achieve this, the current state of reuse practices through the perspective of property companies as clients in decision-making positions was conducted through semi-structured interviews to identify key barriers and enablers associated with reuse. The three most significant barriers that emerged were a lack of measurable economic incentives, the absence of a professional reuse market, and obsolete project management. Conversely, the three most significant enablers were new and improved project management methods, enhancing competence and learning within and beyond organisations, and introduce reuse at an early stage. The results emphasise the need for project management to develop and adopt circular economy principles. This is further understood due to responders highlighting the industry’s linear approach as a major obstacle to circularity together with uncertainties related to product performance, responsibilities and economics characterising reuse efforts. However, an industry in transition is witnessed, e.g. by the emergence of new roles which suggests a continued need for focused research in organisational matters.

This study examines renovation strategies among owners of rental housing in Sweden in response to European energy policies that promote deep renovation as a means to reduce carbon emissions from residential buildings. Case studies of eleven housing companies, seven public and three private, were designed with the aim to examine housing owners’ attitudes and renovation strategies, and how policies and objectives for energy efficiency become incorporated into these attitudes and strategies. Results are illustrated in typologies that distinguish between renovation strategies with either a more commercial or a more societal focus and spanning between deep and partial renovation. The typologies can be used to discuss how different aspects influence renovation, and illustrates how strategies change over time. The study identifies a trend in which housing owners are increasingly relying on partial or over-time renovation. Cost is one important driver, but social responsibility toward tenants and in some cases the protection of cultural heritage are also found to be important. A distrust of fixed models for renovation was observed. The paper questions the concept of deep renovation and suggests instead partial and over-time renovation as a way forward toward sustainable renovation. Partial renovation can bring together energy efficiency with environmental, financial, social, and cultural objectives of housing management. If managed properly, over-time renovation can reduce the risk of an investment, and has the advantage of allowing future technological advancements in energy efficiency to be included in current planning.

The sharing of indoor space can improve space and energy efficiency. The drivers and barriers to space-sharing initiatives are investigated from the perspectives of building users and building sector practitioners, based on interviews and a workshop. The role of energy performance metrics in promoting space efficiency is further analysed through a literature review. From the users’ perspective, space sharing can be understood through the interplay between tangible aspects (e.g. concrete benefits derived from sharing), organisational aspects (e.g. common decision processes and conflict resolution) and social aspects (e.g. group identity and consensus on appropriate behaviours). From the perspective of architects and property owners, shareable spaces require features such as flexibility and multifunctionality. The design of such spaces is limited by regulatory issues (e.g. building regulations poorly accommodate shared facilities) and business-related issues. One such issue is that building performance metrics normalised based on floor area do not incentivise the efficient use of space. A review of complementary metrics is provided, covering parameters such as number of users, layout, time of use, etc. Each metric serves a particular purpose; therefore, a set of complementary metrics can be used to support decisions at different phases of the building’s life cycle.

Practice relevanceImproving space efficiency (e.g. by sharing indoor space) is a key strategy to meet simultaneously the future demand for facilities in cities and fulfil environmental objectives such as a reduction of climate change impact in the building sector. A clearer understanding of the specificities of space sharing is provided from the perspectives of building users and practitioners. This will assist practitioners to understand the needs of other stakeholders. Regulatory and business-related barriers to space-sharing initiatives are highlighted as a first step towards overcoming these barriers. Guidance is provided on complementary energy performance metrics appropriate for space efficiency. These metrics can be used to support various decisions during the different stages of a building’s life cycle.

As urbanization continues and more people move into cities and urban areas, pressure on availablelandfornewconstructionswillcontinuetoincrease. Thissituationconstitutesanincentiveto reviewtheneedforinteriorspaceandusesofexistingbuildings. Agreatdealcanbegainedfromusing existingbuildingsmoreefficientlyinsteadofconstructingnewones: Reducedresourceusageduring construction(investments,naturalresources,andenergy),operation,andmaintenance;moreactivityper squaremeterofbuildingscreatesagreaterbasisforpublictransportandotherservices;moreintensive useofbuildingscreatesamorevibrantcitywithoutbuildingonvirginland. Theaimofthispaperisto initiateadiscussionregardinghowdigitalizationcanaffectthedemandandsupplyofinteriorspace in existing buildings and elaborate on how policy can support more resource-efficient uses of space. New activity-based resource measurements intended for use in buildings are proposed, and several principles that have the potential to decrease environmental impact through more efficient usage of space are outlined. Based on these ideas for encouraging the flexible use of building spaces that are facilitatedbydigitalizationandthenewmeasurementapproaches,afour-stepprincipleforconstruction isproposed: Thefirststepistoreducethedemandforspace,thesecondistointensifyusageofexisting space, the third is to reconstruct and adapt existing buildings to current needs, and the fourth is to constructnewbuildings. Urgingpolitical,municipal,construction,andreal-estatedecisionmakersto contemplatethisprinciple,particularlyinviewofthenewconditionsthatdigitalizationentails,willlead tomoresustainableconstructionand,inthelongterm,asustainablebuiltenvironment.

Vi behöver 710 000 nya bostäder inom en tioårsperiod, men även behovet av andra fastigheter ökar när befolkningen växer. Det är hög tid att lyfta alternativ till att bygga nytt. Här presenteras en fyrstegsprincip för mer effektivt användande av ytor, skriver forskare, fastighetsägare och arkitekter med flera tillsammans.

https://www.dagenssamhalle.se/debatt/har-ar-fyra-smarta-alternativ-till-att-bygga-nytt-17320

Critical moisture level for mould growth on building materials. Mould can grow on building materials in 75-100% relative humidity (RH) at room temperature. How sensitive materials are to mould growth varies. One way to describe this sensitivity is the critical moisture level, RHcrit, the lowest RH at which mould can grow on a material. The critical moisture level for different material groups was proposed based on the current research situation in 2005, in the report ” Microbiological growth on building materials – critical moisture levels. State of the art” (SP Rapport 2005: 11). Based on new research results, these values are no longer valid. This report provides a general overview of the conditions for mould growth on building materials, focusing on the critical moisture level and the new research results. The main conclusion is that RHcrit is a product-specific property. It is impossible to estimate RHcrit for a product based on that it belongs to a group of materials, such as plaster or wood-based boards. Instead, RHcrit must be determined by laboratory tests for each product. The report also discusses how the results of a laboratory test can be used to prevent mould growth in buildings with known RF and temperature and the benefits of using RHcrit instead of traditional mould resistance tests.

Building materials differ in their susceptibility to mould growth. Wood is a material often considered to have a low mould resistance. However, wood is not a homogenous material and different characteristics of the material are expected to have an impact on mould growth. In this paper, it was shown that wood species (pine or spruce), sawing pattern (centre-board or side-board) and surface structure (planed or sawn) affected mould growth. In addition, it was indicated that the susceptibility cannot be described by one single parameter, but also depends on other parameters. It is therefore difficult to estimate the susceptibility of wood in general. These conclusions were drawn from a meta-analysis, using data from five separate, previously performed laboratory studies conducted at 90% relative humidity and 22 °C, and from a laboratory study performed at 95% RH and 22 °C. © 2016 Springer-Verlag Berlin Heidelberg

PVC flooring accounts for a significant share of PVC use in the construction sector and has great potential for recycling. Nevertheless, the actual recycling rate of PVC flooring spillage in 2018 was less than 20%, according to the national system for the separate collection and recycling of material residues from the installation of PVC floorings, developed by flooring manufacturer Tarkett AB and now used by all manufacturers in the flooring industry. To improve the sorting and recycling process of old PVC flooring it is necessary to identify where the material is located and evaluate its recycling potential. Such information is crucial for demolition waste recycling companies and flooring manufacturers to improve recycling practices for PVC flooring and then use the recycled PVC materials in the new flooring production. The challenge is to find out in which buildings there is PVC flooring and when it was installed which will indicate when it is planned to be dismantled and replaced. Since the PVC flooring manufactures do not keep track on where their products are laid such information is lacking. The best source of information that was made available for the researchers appeared to be the public building owners´ maintenance plans. Therefore, it was decided to focus on the presence of PVC flooring in public preschools as an example. By combining data from maintenance plans with national building registers, the PVC flooring in the Swedish preschools have been forecasted. The project results show an example how limited data sources can be used to predict presence of materials in larger stocks and is therefore expected to contribute to a climate-neutral supply chain with recycled PVC flooring. Based on the results of this study, dialogue, recommendations and guidelines can be developed for the flooring industry, the waste and recycling industry and the Swedish real estate and construction sector.

Purpose – Building owners are encouraged to reduce the energy consumption both in order to contribute to national energy saving goals and to reduce the costs of heating and operation of buildings. However, it is important to pursue the most optimal strategy to achieve cost-effective energy use while maintaining other values. Building managers often do not have the time or expertise to make a proper evaluation of the available options, hence there is a need for practical methodologies for evaluation of renovation alternatives. The paper aims to discuss these issues. Design/methodology/approach – Renobuild, a systematic approach for evaluating renovation alternatives based on sustainability criteria are under development. It aims to compare renovation alternatives from an environmental, economic and social perspective. To verify the methodology it has been used to evaluate different renovation alternatives for a multi-family apartment building in Sweden. Findings – The study showed that building managers are provided with a clear comparison between different renovation alternatives from a sustainability perspective. Using Renobuild or similar methodologies may highlight renovation measures which marginally increases the investments, but can lead to significant environmental and social benefits. Research limitations/implications – So far the methodology has only been tested on a limited number of buildings in Sweden. More buildings will need to be tested for further verification. Originality/value – Not many tools or methodologies exist which address several aspects of sustainability. Renobuild is a practical methodology that can help building owners to increase focus on sustainability.

Building owners are encouraged to reduce energy use in order to both contribute to national energy-saving goals and reduce the costs of heating and operation. It is important to choose the most optimal renovation measures available so as to achieve cost-effective energy use while maintaining excellent indoor environments, without sacrificing architectural quality or negatively affecting the environment. Building owners and managers often have neither the time nor the expertise required to properly evaluate the available renovation options before making a final decision. Renovation measures are often calculated to repay investments in a short time, rather than taking into account life-cycle costs (LCC), despite the fact that a thoughtful, comprehensive renovation is often more cost-effective in the long run. This paper presents a systematic approach for evaluating different renovation alternatives based on a number of sustainability criteria. The methodology has been verified using three multi-family apartment buildings in Sweden. The benefit of using the proposed methodology is made clear through a comparison between the different renovation alternatives from a sustainability perspective, and will hopefully serve as encouragement to choose renovation measures which involve marginally increased investments but lead to significant environmental and social benefits in the long-term.

The financing of energy efficiency measures and renovations is key to reaching energy efficiency targets for the housing sector. The purpose of this article is to add the Swedish case of how capital market funds have become accessible and used by public and private housing companies, in particular for energy efficiency measures. The core of this article are interviews with representatives of Swedish housing companies made during the spring of 2021 with the purpose of mapping how public and larger private housing companies finance renovation and energy efficiency measures, and to what extent funds from the capital market are used for these purposes. In this article, we have found that capital market funds are commonly used by the Swedish public and the largest private housing companies. Bonds are less costly compared to bank loans, and green bonds are 0.02–0.03 percentage points less costly than conventional bonds. Furthermore, control systems that investigate the values of building portfolios as security for bonds are poor. A conclusion is that governmental control systems over the capital market issuing bonds for the housing market could be needed to avert future housing bubbles. © 2022, The Author(s).

Byggsektorn står inför ett stort renoveringsbehov. Byggnader från miljonprogramstiden har nått en ålder då många olika byggnadsdelar når sin förväntade livslängd. Detta renoveringsbehov är inte jämnt fördelat bland Sveriges fastighetsägare. Det stora flertalet av de ännu ej renoverade byggnaderna från miljonprogramstiden ägs av fastighetsbolag knutna till SABO, men det finns även många privata fastighetsägare och bostadsrättsföreningar som har ett eftersläpande renoveringsbehov eller som har renoverat men fortfarande har en hög energianvändning och alltså troligtvis inte genomfört nödvändiga energieffektiviseringsåtgärder. Det finns också olika förutsättningar för att göra de investeringar som krävs, vilket beror på företagens soliditet, fastigheternas värde och möjligheten att få lån, utrymme för hyresökning etc. Detta gör att renoveringstakten inte kommer att täcka renoveringsbehovet och att vissa delar av fastighetsbeståndet kommer att vara mer eftersatt.

Byggsektorn är inne i en period av mycket hög aktivitet. Över 700 000 nya bostäder efterfrågas, samtidigt som miljonprogrammets byggnader börjar nå sin förväntade livslängd. Detta är en enorm utmaning, men det är också en möjlighet, där vi kan nå energi- och klimatmål och skapagoda boendemiljöer till rimlig kostnad.

ByggaF is a methodology for including moisture safety in the construction process that was developed and presented in 2007. ByggaF comprises methods to secure, document and communicate moisture safety throughout the construction process, from planning to management. The methods involve a standardized way of working designed to meet the demands of society and the client’s requirements for moisture safety. On request from the Swedish construction sector, ByggaF has been transformed into an industry standard. Since then, ByggaF has been used in a number of Swedish construction projects. One reason for the broad implementation of ByggaF is that the Swedish environmental assessment tool Miljöbyggnad demand for using ByggaF in order to reach “silver level” or “gold level”. Another reason is that more than 100 moisture experts have been trained to use ByggaF to assure a moisture safe building process. There has also been interest in using ByggaF expressed from other countries. The industry standard has been translated to English but it needs to be adjusted to country specific conditions, such as regulation and building practices in order to be applied in other countries. In Finland, the Swedish version of ByggaF has been adapted to Finnish regulations and used for including moisture safety in construction of a school at Bergö. There have also been attempts to adjust ByggaF to suit specific applications such as construction of prefabricated single family houses and renovation of multifamily houses.

The escalating utilisation of second homes has led to an extension in heating periods and, to a certain degree, renovations to elevate the standard, resulting in augmented energy and resource consumption. A comprehensive survey was conducted in Sweden, examining user patterns across different seasons, heating systems, and implemented energy efficiency measures. The results indicate that second homes are occupied for extended periods during the summer season and intermittently throughout the year. Over half of the second homes are heated even when unoccupied, with 12% maintaining a temperature above 16 °C. The predominant heating method is direct electricity (32.2%), followed by heat pumps (29.5%) and stoves (17.5%). A variety of renovations are undertaken, primarily to enhance the standard and technical performance, but also to implement energy efficiency measures such as window replacement, additional insulation, or heat pump installation. Based on the reported user and heating patterns, and the energy renovations carried out, the potential energy savings with different energy renovation strategies were estimated for the Swedish second home stock. The results show that though lowering the temperature when a second home is unoccupied emerges as the most efficient measure, both in terms of cost-effectiveness and climate impact, it needs to be complemented with intermittent heating or dehumidification to ensure that the relative humidity is below critical levels, to avoid the risk of damages caused by, for example, mould growth. Installing a heat pump is the second most energy- and cost-effective measure and has the advantage that the indoor temperature can be maintained at rather high levels.