Swedish Building Research Articles

Maintenance of Painted Steel-sheet Roofs on Historical Buildings in Sweden

ABSTRACT This work presents a model and tools with which stakeholders and others involved in the conservation and maintenance process to make informed, evidence-based decisions for the treatment of painted steel-sheet roofs on historical buildings. The aim is to bridge the communication gap between research and practice and to provide useful tools for balancing technical, economic, environmental and historical values. The presented research is based on research and field experiences from practice in Sweden, and focuses on the different stages of building conservation: anamnesis, diagnosis, therapy and control/monitoring. The results are exemplified by systematic descriptions of material characteristics, anticorrosive treatment procedures and quality control checkpoints. A material and method matrix is proposed that can be used in diagnosis, planning and documentation of general procedures, or which can be refined for specific object procedures. It could be used for comparing cases, for suggesting areas of further work or for setting minimum levels for documentation. The matrix can be connected to different quality standards of conservation. It may favour the communication and systematic assessment of working procedures for different substrates, and the further development of best practices.

Cooling of office buildings in cold climates using direct ground-coupled active chilled beams

This study investigates the use of a direct ground cooling system (DGCS) using active chilled beams for the cooling of office buildings in Sweden. The methodology of the study entails laboratory experiments to develop and validate a simulation model of the cooling system. The sensitivity of the input parameters, such as borehole heat exchanger (BHE) length, internal heat gains and room temperature set point, are studied with respect to BHE outlet fluid temperature and room thermal comfort. The results provide a practical insight into designing DGCSs with regard to borehole outlet fluid temperatures. The results also show that the thermal comfort criteria in the room are met by applying the DGCS even under the most critical design conditions of undisturbed ground temperature and internal heat gains. The sensitivity study quantifies the influence of the room temperature setpoint and internal heat gain intensity on the BHE length. The BHE outlet temperature level is more sensitive in shorter BHEs than in the longer ones, and BHE length and room temperature levels are highly correlated. Thus, the sizing of DGCS can benefit from a control system to allow the room temperature to float within a certain range.

Techno-economic assessment of grid-connected photovoltaic systems in Swedish public buildings

Sweden aims to achieve near-zero non-renewable energy use in all the newly constructed buildings from 2020. One of the most promising methods of achieving these energy goals and reducing the net energy-use is using solar photovoltaic (PV) systems in buildings. Although some studies have demonstrated this method, the solar PV industry is growing rapidly. Therefore, the study aimed at using sources with the latest information to analyse the true potential of PV systems for the current initial cost of the PV system and tax benefits in Sweden. The study investigates the economic feasibility of a grid-connected solar PV system from a technical and economic perspective for a group of public buildings in Sweden. The hourly energy production and cost of purchasing deficit electricity was simulated for various tilts and ground coverage area to find the optimum tilt and ground coverage ratio of PV panels. The PV energy supply of four different systems – 26 kWp, 75 kWp, 80 kWp, 155 kWp – in different locations was simulated. The overproduction, own usage rate, solar fraction, investment cost, profit over its lifespan and the payback period of each system were compared for the existing as well as improved energy use. Honeybee 0.0.64 and SAM 2018.11.11 was used to simulate energy use and PV production. Results indicate that a system with a high own usage rate and specific yield was profitable when the selling price of electricity (excluding tax refund) was lower. However, a system with a higher production potential became more profitable when the selling price of electricity (including tax refund) was equal or higher than the purchasing price. Additionally, a sensitivity analysis was conducted to demonstrate the feasibility of the system if the price of electricity or interest rates changed in the future. The outcome of this research demonstrates the techno-economic feasibility of implementing a solar PV system in Sweden and provides a set of benchmarks for comparison of such systems around the world.

Measured and Simulated Energy Use in a Secondary School Building in Sweden—A Case Study of Validation, Airing, and Occupancy Behaviour

In this case study, the energy performance of a secondary school building from the 1960s in Gävle, Sweden, was modelled in the building energy simulation (BES) tool IDA ICE version 4.8 prior to major renovation planning. The objectives of the study were to validate the BES model during both occupied and unoccupied periods, investigate how to model airing and varying occupancy behaviour, and finally investigate energy use to identify potential energy-efficiency measures. The BES model was validated by using field measurements and evidence-based input. Thermal bridges, infiltration, mechanical ventilation, domestic hot water circulation losses, and space heating power were calculated and measured. A backcasting method was developed to model heat losses due to airing, opening windows and doors, and other occupancy behaviour through regression analysis between daily heat power and outdoor temperature. Validation results show good agreement: 3.4% discrepancy between space heating measurements and simulations during an unoccupied week. Corresponding monthly discrepancy varied between 5.5% and 10.6% during three months with occupants. Annual simulation indicates that the best potential renovation measures are changing to efficient windows, improved envelope airtightness, new controls of the HVAC system, and increased external wall thermal insulation.

Study on the characteristics of work‐unit type in spaces for individual learning of pupils and students: A case study on the work‐unit type school buildings in Sweden

The aim of this paper is to clarify the spatial characteristics of work-units comprising advanced school buildings in Sweden based on the learning activities of pupils and students. The results of this study are as follows. A work-unit is composed of seven to nine types of rooms and two types of partitions. Work-units include four types of learning of the same content together, and three types of learning in small groups or by individuals. The rooms in a work-unit are separated by doors and removable partitions. This enables students to set the spaces for learning by themselves, by opening/closing the doors or rearranging the partitions. In higher grades, students can be provided the opportunity to choose their own spaces and content for learning.

Does facility management affect perception of building quality?

PurposeThis paper aims to examine the strategy, selection and perception of facility management (FM) services and the effect it may have on perceived building quality.Design/methodology/approachData was collected through a survey distributed to board members of cooperatives for newly constructed buildings in Sweden. Responses from 394 cooperative boards were included in the data set and analysed. The difference in cooperative choice of FM strategy and satisfaction with FM services was examined with non-parametrical Kruskal–Wallis tests and the effect of FM strategy and satisfaction with FM services on perceived building quality was examined with a one-way analysis of variance (ANOVA) test.FindingsThe results suggest information asymmetry and indicate urgent need for an objective accreditation system for FM services, which will inform and assist housing owners in the FM selection process. The study validates the hypothesis that facilities management strategies applied by housing cooperatives have a significant effect on perception of building quality.Practical implicationsThe findings will assist developers, facility and property managers to understand the needs and services valued by the housing cooperative. The findings highlight the information asymmetry, restricted techniques and weak signalling methods among FM services, and advocates promoting an objective accreditation system for FM services.Originality/valueThe study contributes to the discussion on the concept of building quality and the results presented provide a better understanding of facilities management strategy on perception of building quality.

A review of the Swedish fire safety regulation: From the industry's perspective

SummaryAs in many countries, the Swedish building regulation is constantly updated. In most cases, these updates are small and do not affect the overall structure of the building code. However, from time to time, larger changes are made and the framework of how to use the code is changed. The latest of these major changes was made in 2011 and the code is since then a mix of performance‐based and prescriptive requirements. During 2016, a study was initiated with the purpose to get the Swedish fire safety industry's perspective on the current structure of the Swedish building code and how the code should be developed in the future. This study concludes that there are substantial differences within the fire safety industry on the view of the building code. Both on the state of the current code and on how the code should develop in the future. However, in some points, the majority of the participants agree, for example, most participants think that the control system for ensuring fire safety should be expanded, both in the design and in the construction phase.

Effects of Architectural Space Layouts on Energy Performance: A Review

As one of the most important design tasks of building design, space layout design affects the building energy performance (BEP). In order to investigate the effect, a literature review of relevant papers was performed. Ten relevant articles were found and reviewed in detail. First, a methodology for studying the effects of space layouts on BEP were proposed regarding design variables, energy indicators and BEP calculation methods, and the methodologies used in the 10 articles were reviewed. Then, the effects of space layouts on energy use and occupant comfort were analysed separately. The results show that the energy use for heating, cooling, lighting and ventilation is highly affected by space layouts, as well as thermal and visual comfort. The effects of space layouts on energy use are higher than on occupant comfort. By changing space layouts, the resulting reductions in the annual final energy for heating and cooling demands were up to 14% and 57%, respectively, in an office building in Sweden. The resulting reductions in the lighting demand of peak summer and winter were up to 67% and 43%, respectively, for the case of an office building in the UK, and the resulting reduction in the air volume supplied by natural ventilation was 65%. The influence of other design parameters, i.e., occupancy and window to wall ratio, on the effects of space layouts on BEP was also identified.

Unified Methodology to Identify the Potential Application of Seasonal Sorption Storage Technology

In this study, the definition of a new methodology for a preliminary evaluation of the working boundary conditions under which a seasonal thermal energy storage (STES) system operates is described. The approach starts by considering the building features as well as the reference heating system in terms of solar thermal collectors’ technology, ambient heat sinks/source, and space heating distribution systems employed. Furthermore, it is based on a deep climatic analysis of the place where the STES needs to be installed, to identify both winter and summer operating conditions. In particular, the STES energy density is evaluated considering different space heating demands covered by the STES (ranging from 10% up to 60%). The obtained results demonstrate that this approach allows for the careful estimation of the achievable STES density, which is varies significantly both with the space heating coverage guaranteed by the STES as well as with the ambient heat source/sink that is employed in the system. This confirms the need for careful preliminary analysis to avoid the overestimation of the STES material volume. The proposed approach was then applied for different climatic conditions (e.g., Germany and Sweden) and the volume of one of the most attractive composite sorbent materials reported in the literature, i.e., multi-wall carbon nanotubes (MWCNT)-LiCl, using water as the working fluid, needed for covering the variable space heating demand in a Nearly Zero Energy Building (NZEB) was calculated. In the case of Swedish buildings, it ranges from about 3.5 m3 when 10% of the space heating demand is provided by the STES, up to 11.1 m3 when 30% of the space heating demand is provided by the STES.

The role of values for niche expansion: the case of solar photovoltaics on large buildings in Sweden

BackgroundSolar photovoltaic (PV) plants can contribute to the transformation of the electricity system in Sweden not only by adding capacity, but also by forming new decentralized ownership structures and involving new actors. This article focuses on solar PV plants on larger buildings, which represent a significant share of the installed capacity (although the total capacity is still very low in Sweden) and which have a good future potential. We are interested in the reasons owners of large buildings have for investing in solar PV plants, despite the fact that they face a complex regulatory situation. The aim of this paper is, therefore, to identify added values from solar PV plants for large buildings and to see how these values contribute to the ongoing expansion of the solar PV niche in Sweden. We use sustainability transitions as the theoretical point of departure and focus particularly on the role of values in an expanding niche. Data was collected via 15 semi-structured interviews, mainly with large building owners. It provides an interesting empirical case of the pioneers within the actor group of large building owners who potentially can play an important role in the expansion of solar PV technology in Sweden. Theoretically, the article contributes to the sustainable transition research field by demonstrating how values are developed and affect the niche-regime interplay.ResultsThe findings demonstrate that owning a solar PV plant adds values such as sustainability, fair cost, and induced innovativeness. These values have an effect on niche expansion by contributing for example to the development of a social network, new role development, positive niche narrative, and niche empowerment.ConclusionsWe conclude that the broad set of values added by solar PV plants on large buildings increases the desire and enhances the positive experience to take on a new role development. Furthermore, we conclude that added values contribute to developing a social identity which is important when expanding the social network around the niche. Finally, we conclude that added values shape the positive niche narrative among niche advocates and give direction for policy development related to the niche.

Development and validation of energy signature method – Case study on a multi-family building in Sweden before and after deep renovation

Building energy use constitutes a large part of total energy use, both in the European Union and Sweden. Due to this energy use, and the resulting emissions, several goals for energy efficiency and emissions have been set. In Sweden, a large portion of multi-family buildings were built between 1960 and 1980, which have major energy savings potential. The purpose of this paper is further development and validation of previously introduced energy signature method and its inherent parameters. The method was applied on a multi-family building where thermal energy data supplied by the district heating company was available before and after deep renovation. Using IDA ICE, a building energy simulation (BES) software model was created of the building, to aid in validation of the energy signature method. The paper highlighted the accuracy of the proposed energy signature (PES) method and a sensitivity analysis on the inherent parameters have been performed. The results showed new ways of treatment of the thermal energy data and revealed how more information can be extracted from this data.

The Life and Death of Residential Room Types: A Study of Swedish Building Plans, 1750–2010

While the study of building types is a well-known and relatively active research field, the topic of room types is less explored. This article takes a broad approach to spatial categorization, enabling the examination of different types of spaces over longer periods. How do different room types evolve and die? How do the different residential room types relate to each other? Do they act alone or do they follow each other over time? The article looks at the particular evolution and development of Swedish residential room types and is based on the study of plans of 2,340 Swedish buildings from about 1750 to 2010. Six themes emerged from this study: thresholds of birth and extinction, abruptive change, the relation between absent and present room types, contagious types, different temporal scales and the stabilization of prototypical sets.

Implications of supplying district heat to a new urban residential area in Sweden

Here we analyze the cost, primary energy and CO2 implications of supplying district heat, considering different supply and return temperatures, to a new residential area in Växjö, Sweden. We explore four land exploitation alternatives consisting different types of buildings with various heated floor areas as well as occupancy densities and two levels of building energy efficiency, based on the Swedish building code and passive house criteria. The analysis shows that energy performance of the buildings and land exploitation alternatives strongly influence the annual heat demand and its profile, which steers the design of the local heat distribution network. Additionally, supply and return temperatures of district heat somewhat influence the design of the network. The distribution heat losses could be reduced by 25% and 50% if district heating systems of 65/30 °C and 50/20 °C, respectively, are used instead of a conventional 80/40 °C system. However, for the same land exploitation alternative, the local distribution heat losses are about the same whether or not the buildings are designed to meet the Swedish building code or passive house criteria, since the same pipe distance is required and the variation of pipe diameters is small. A 50/20 °C system increases electricity use to boost hot water temperature to avoid the risk of legionella bacteria, and this influences quantity of district heat supply, primary energy use and costs. Therefore, a 65/30 °C system appears to be more primary energy and cost efficient than a 50/20 °C system. Increased insulation of district heating network reduces heat losses but this is not cost effective due to increased investment cost. The results are similar whether or not the analysis is based on current energy supply or future renewable based energy supply. This study increases understanding of strategies for planning and designing new urban residential areas and their energy supply systems to reduce primary energy use as well as monetary costs, and to minimize the climate impacts of the built environment.

Numerical and real-life assessment of the moisture safety of CLT structure with PIR insulation composite under the Swedish climate

The building industry is a major contributor of CO2 emission. Wood construction is a good option for carbon storage among various construction alternatives. Considering the growing market of multi-story wooden building in Sweden, CLT (cross laminated timber) structure with an alternative insulation composite with PIR insulation and MgO board was proposed. In order to prove the applicability of this construction for moisture safety, the hygrothermal performance of the wall was measured in real life at HSB Living Lab (Gothenburg, Sweden) throughout 2019. Furthermore, a numerical model to analyse its performance by transient heat and moisture transfer analysis was created to predict the performance of the wall system. After the successful validation of the numerical model, a parameter study was carried out to investigate the moisture risk of the wall system in the case of extensive wetting of the CLT panel and in various areas in Sweden (Gothenburg, Stockholm, Lund, Karlstad and Luleå). The study showed a low mould growth risk either in the test at the living lab or in the feasibility study. The development of the technology should further focus on the cost-effectiveness and design of all the construction details for the future market application.

Pressure distribution around the thermal envelope - a parametric study of the impact from wind and temperature on contaminant transport within a building

Several school buildings in Sweden have indoor air quality problems. The contaminant source is often assumed to come from within the construction, for example from the crawl space or attic space. Contaminants, in these cases, are transported by air leaking between compartments in the building. Here, the driving force for the air leakage is difference in pressure and, therefore, determining pressure also determines the direction of contaminant transport. In many cases, measures to improve the air quality are taken without a thorough understanding of how it might affect the pressure distribution in the building. In this paper a numerical model is used to examine how different climate scenarios and different building configurations affect the leakage and contaminant transport in a building with a crawl space. Results show that for leaky buildings the ventilation rate increases with increased wind and therefore the contaminant concentration decreases. The worst scenario in terms of high contaminant concentration is mild days with little wind. Also, when installing an exhaust fan in the crawl space with the purpose to prevent air from leaking from the crawl space to the classroom it is advisable to also consider the airtightness and the climate, not only the pressure difference across the floor.

Energy and indoor thermal comfort performance of a Swedish residential building under future climate change conditions

The latest climate change projections for Sweden suggest mean annual temperature increase of up to 5.5 °C by 2100, compared to 1961-1990 levels. In this study we investigate the potential impacts of climate change on the energy demand for space conditioning, overheating risk and indoor thermal comfort of a modern multi-storey residential building in Sweden. We explore climate change adaptation strategies to improve the building’s performance under the climate change conditions, including increased ventilation, solar shading, improved windows and mechanical cooling. The building is analysed under future climate projections for the 2050-2059 time frame, with representative concentration pathway (RCP) 2.6, 4.5 and 8.5 scenarios. The building’s performances under these future climates are compared to those under the historical climate of 1961-1990 and recent climate of 1981-2010. The results suggest that climate change will significantly influence energy performance and indoor comfort conditions of buildings in the Swedish context. Overheating hours and Predicted Percentage of Dissatisfied (PPD) increased significantly under the future climate scenarios. Furthermore space heating demand is reduced and cooling demand is increased for the studied building. However, effective adaptation strategies significantly improved the buildings’ energy and indoor climate performances under both current and future climate conditions.

Relying on reference cases when evaluating new technical solutions? Evaluation of technical documentation in a case study

Serial failures have occurred when introducing new technical solutions in the Swedish construction industry. In an earlier interview study exploring introduction of new technical solutions, documentation and reference cases provided by the supplier are given as the main sources for evaluation. This paper aims at addressing the questions: 1. What kind of documentation concerning building physics are provided by suppliers? 2. How well does the suppliers’ documentation meet the need for verification? In order to address these questions, the case of hygrothermal performance of cross laminated timber structures in multifamily dwellings was chosen. An inquiry of data was sent out to four suppliers at the Swedish market, asking for documentation and reference cases provided. Based on the documentation given, an assessment was made of to which extend the documentation can support verification of appliance to the relevant requirements of the Swedish building regulations. The case study shows reference cases are scarce and existing documentation is not comprehensive, thus indicating the building industry might have a disproportional high confidence in reference cases. The results will be used to suggest requirements for reference cases to be used for verification.

Limits to polycentricity? Institutional layering and policy feedbacks of building energy performance requirements in Sweden

AbstractLocal governments have come to play an increasingly active role in addressing current environmental challenges. In addition to improving the environmental performance of a specific city, such initiatives can potentially spur policy change at other levels of government and thereby contribute to the addressing of global environmental challenges. This type of interplay between local and higher levels of government has been insufficiently addressed by environmental governance research. This study addresses this research gap by looking at the case of regulatory energy performance requirements on buildings in Sweden. Through a case study methodology, the research turns to policy documents and interviews. The research shows how local energy performance requirements on buildings provided tensions that impeded their own longevity but contributed to raising ambitions in national regulation. The research contributes to work on polycentric governance by accounting for the existence of hierarchies through the use of concepts from historical institutionalism. In this regard, the study suggests that governance initiatives are prone to institutional layering that, through policy feedback processes, conditions their impact in terms of reaching overarching policy goals. The research is important as it adds empirical substance to the discussion on the potential and limits of local governments in addressing current environmental challenges.

The Effect of High Occupancy Density on IAQ, Moisture Conditions and Energy Use in Apartments

Apartments built in Sweden during the record years 1961–1975 with the aim to remedy the housing shortage and abolish poor standards, were designed for a normal-sized family of 2–4 persons. The mechanical ventilation system, if existing, was primarily designed to ensure an air exchange in the apartment according to Swedish building regulations. During the last few years, the number of overcrowded apartments has increased due to housing shortage in general but also due to migration. Another aspect is that the ventilation in many apartments built during the record years is already insufficient at normal occupant load. The question is how doubling or tripling the number of occupants and thus, the moisture load will affect the risk of bad air quality and moisture damage. To find out, simulations were made to estimate whether it is possible to obtain sufficient air quality and low risk of moisture damage by only increasing the ventilation rates in existing systems or introducing new ventilation systems with and without heat recovery and what the consequence would be in terms of the additional energy demand. Measurements from earlier studies of CO2 and moisture supply in Swedish apartment buildings were used as input data.

Investigating cost-optimal energy renovation of a multifamily building in Sweden

A significant reduction in energy use in the building stock is a major challenge for the future, and doing this in a cost-effective manner is important. This study uses an optimization approach to identify life cycle cost (LCC) optimal energy efficiency measures (EEMs) to implement as part of a renovation of a multifamily building in Sweden. The studied building is a multifamily building with a lightweight concrete construction and an exhaust air ventilation system, built in 1961. The optimization tool OPERA-MILP is used. The energy renovation approaches are compared to both the performed energy renovation of the building and a validated dynamic energy simulation model in IDA ICE 4.8. The results show that under the given framework conditions and assumptions it is not cost-optimal to improve the thermal performance of the building envelope or to implement heat recovery ventilation measures to reduce the space heating demand in the building when considering a life cycle of 40 years. Balanced mechanical ventilation system with heat recovery is cost-effective when an energy saving target of 40% is introduced. The energy renovation of the building has a slightly higher LCC than the cost-optimal level, and it would have been more cost-effective to add more insulation to the façade instead of the attic to achieve the same level of energy saving. A sensitivity analysis has been performed to reveal the effect of the discount rate, energy price, cost of EEMs, thermal properties of the building envelope and windows’ solar heat gain factors on the LCC.