Search

Building archetype identification is crucial for Urban Building Energy Modeling (UBEM), but is still considered one of the biggest challenges in this field. New methods of data acquisition, along with data mining techniques such as clustering, have recently received attention for the possibility of significantly increasing identification reliability and archetype accuracy. This paper aims to establish a new and simple clustering methodology for developing building archetypes for hybrid UBEM, using open data sets and multiple diverse variables, that is still reliable and possible to validate without the use of metered energy use or real building data. The methodology uses k-means clustering for 10 building parameters simultaneously, including socio-economic parameters obtained using spatial interpolation of statistical values. Building archetypes are successfully developed for the residential building stocks of two case study areas in Sweden. The results also show that the error metric values for multiple iterations diverge after a certain number of clusters, even when using the same clustering methodology on the same data set. This discovered effect, along with the combined use of one well-known and one novel error metric, constitutes a framework well adapted to accurately determining the optimal number of building archetypes., Title in the list of papers of Lukas Dahlströms thesis: Optimising the identification of representative building archetypes: A novel approach using multi-parameter cluster analysis and publicly available databases

Rätten, hållbar energianvändning och bevarandet av kulturvärden

This study presents an in-depth analysis of 69 case studies focusing on the energy retrofit of historic buildings, uncovering challenges, best practices, and lessons learned to balance energy efficiency improvements with heritage preservation. The findings highlight several challenges encountered during renovations, such as complex heritage evaluations, restrictions on alterations, coordination issues with authorities, technical limitations, higher investment costs, and knowledge gaps. On the other hand, identifying factors promoting renovation, including demonstrating energy savings while respecting heritage, early collaboration between planners and authorities, and quantifying investments, could incentivize owners and authorities. The limitations of a still-limited sample size, occasional incomplete data, and potential sample bias call for cautious interpretation of the presented analysis. Despite these, the study provides valuable insights into successful projects, emphasizing the need for scalability, knowledge transfer from innovative policies, and targeted policy-making for successful replication. The study concludes with a call for further development of the HiBERatlas (Historic Building Energy Retrofit atlas), an extensive resource for historic building renovation, expanding its database, collaborating with agencies, and tailoring guidance for stakeholders to foster energy retrofits in heritage buildings.

Building archetype identification is crucial for Urban Building Energy Modeling (UBEM), but is still considered one of the biggest challenges in this field. New methods of data acquisition, along with data mining techniques such as clustering, have recently received attention for the possibility of significantly increasing identification reliability and archetype accuracy. This paper aims to establish a new and simple clustering methodology for developing building archetypes for hybrid UBEM, using open data sets and multiple diverse variables, that is still reliable and possible to validate without the use of metered energy use or real building data. The methodology uses k-means clustering for 10 building parameters simultaneously, including socio-economic parameters obtained using spatial interpolation of statistical values. Building archetypes are successfully developed for the residential building stocks of two case study areas in Sweden. The results also show that the error metric values for multiple iterations diverge after a certain number of clusters, even when using the same clustering methodology on the same data set. This discovered effect, along with the combined use of one well-known and one novel error metric, constitutes a framework well adapted to accurately determining the optimal number of building archetypes., Title in the list of papers of Lukas Dahlströms thesis: Optimising the identification of representative building archetypes: A novel approach using multi-parameter cluster analysis and publicly available databases

Due to rapid urbanisation and the significant contribution of cities to worldwide energy use and greenhouse gas emissions, urban energy system planning is growing more important. Urban building energy modelling (UBEM) draws increasing attention in the energy modelling field due to its inherent capacities for modelling entire cities or building stocks, and the potential of varying data inputs, approaches and applications. This review aims to identify best practices and improvements for UBEM applications by examining previous research, with a focus on the currently least established approaches. Different archetype development procedures are analysed for common problems, six main under-developed input approaches or parameters are identified, and applications for future scenario development are surveyed. By analysing previous studies in related fields, this paper provides an overview of gaps in the published research and possible additions to future UBEM projects that can help expanding the existing modelling procedures. Comprehensive human behaviour models with additional aspects beyond occupant presence are identified as a major point of interest. Further research on socio-economic parameters, such as household income and demographics, are also suggested to further improve modelling. This study also underlines the potential for utilising UBEM as a tool for evaluating future climate change scenarios.

Many massive historic buildings such as stone churches are intermittently heated. The predominant heating strategy is to heat the building with as high heating power as possible to achieve a fast and energy efficient heat-up process. However, the fast change rate of temperature induces a high change rate of relative humidity, which can be dangerous for interiors and objects in churches. It has been suggested that the change rate of relative humidity should be limited with respect to conservation. Desorption from the walls has a significant effect on the change rate of relative humidity. Typically, the absolute humidity can increase by 50% when the church is heated. Based on a hygrothermal model that allows for a prediction of both temperature and absolute humidity as function of time, this paper presents a model-based feed-forward control algorithm that calculates the maximum hourly heating power increase allowed for limit the change rate in relative humidity to a pre-defined value. The control algorithm is validated using simulations.

Purpose Energy use in buildings needs to be reduced to meet political goals; however, reducing energy use can conflict with heritage preservation objectives. The purpose of this paper is to demonstrate a method that combines quantitative and qualitative analyses of the potential of energy savings in an historic building stock. Specifically, this study examines how requirements of historic building preservation affect the energy saving potential on a building stock level. Design/methodology/approach Using the World Heritage Town of Visby, Sweden as a case study, this paper illustrates a step-by-step method as a basis for implementing energy savings techniques in an historic building stock. The method contains the following steps: categorisation of a building stock, definition of restriction levels for energy renovation scenarios and life cycle costs optimisation of energy measures in archetype buildings representing the building stock. Finally, this study analyses how different energy renovation strategies will impact heritage values and energy saving potentials for different categories of buildings. Findings The outcome of the study is twofold: first, the method has been tested and proven useful and second, the results from the application of the method have been used to formulate differentiated energy renovation strategies for the case study. Originality/value The study shows that it is possible to integrate techno-economic analysis with assessment of heritage values in a given building stock in order to facilitate a strategic discussion balancing policies and targets for energy savings with policies for the preservation of heritage values. The findings will contribute to sounder policy development and planning for historic building stocks.

Purpose Improving the energy performance of historic buildings has the potential to reduce carbon emissions while protecting built heritage through its continued use. However, implementing energy retrofits in these buildings faces social, economic, and technical barriers. The purpose of this conceptual paper is to present the approach of IEA-SHC Task 59 to address some of these barriers. Design/methodology/approach Task 59 aims to achieve the lowest possible energy demand for historic buildings. This paper proposes a definition for this concept and identifies three key socio-technical barriers to achieving this goal: the decision-makers' lack of engagement in the renovation of historic buildings, a lack of support during the design process and limited access to proven retrofit solutions. Two methods - dissemination of best-practice and guidelines - are discussed in this paper as critical approaches for addressing the first two barriers. Findings An assessment of existing databases indicates a lack of best-practice examples focused specifically on historic buildings and the need for tailored information describing these case studies. Similarly, an initial evaluation of guidelines highlighted the need for process-oriented guidance and its evaluation in practice. Originality/value This paper provides a novel definition of lowest possible energy demand for historic buildings that is broadly applicable in both practice and research. Both best-practices and guidelines are intended to be widely disseminated throughout the field.

Solar energy applications have, in recent years, become a common element in the urban landscape, especially on roofs and facades. However, it is important that the integration of solar energy in the built environment do not distort the fabric or expression of the existing building envelope, not at least in areas of high cultural-heritage values. The aesthetics depend, to a large extent, on how visible the new technology, such as photovoltaic (PV) panels, is. This paper describes a method for visibility assessment of building envelopes. It is referred to as target-based as it, in contrast to previously reported methods, bases the assessment from the perspective of the building envelope itself, rather than possible vantage points on the ground. The method was evaluated for two Swedish cities; Stockholm and Visby. In Stockholm, each building was evaluated based on its cultural-heritage values, solar irradiation and visibility. Deploying PV only on the roofs with the lowest cultural-heritage values, with insolation > 900 kWh/m2, and with no visibility from ground, results in a total PV yield of up to 2% of the total electricity demand. In Visby, various definitions of the vantage area were evaluated, from which the building envelope can be seen. It was found that the choice of vantage area greatly impacts the solar energy potential. If the vantage area is defined by the public domain, i.e., streets and other public open spaces, the non-visible roof area doubles compared to if all ground/terrain defines it. Compared to previous studies, the use of a vantage area, instead of discrete vantage points, seems to result in higher visibility of the roofs.

The indoor climate of historic buildings is governed not only by human comfort but also the desire to preserve these buildings and their interiors. For preservation, relative humidity is the most important parameter, including its amplitude and change rate. To control the change rate of relative humidity at a heat-up event for an intermittently heated massive historic building with heavy masonry walls, a simplified model for heat and moisture transfer at the heat-up time is presented. A method to derive the time constants and hygrothermal parameters of the building from measurements taken during a step response test is proposed and validated. The model with its parameters can be used to predict both heat-up time to reach the target temperature as well as the amount of moisture gained from the walls. These predictions are in turn used to calculate the decrease in relative humidity during the heat-up event. The indoor air relative humidity is predictable as it is determined by the air temperature and air mixing ratio. A control algorithm that uses the model for predicting and controlling the change rate of relative humidity by shaping the heating power is presented and validated using simulation results.

A new methodology for long-term monitoring of climate change impacts on historic buildings and interiors has been developed. This paper proposes a generic framework for how monitoring programs can be developed and describes the planning and arrangement of a Norwegian monitoring campaign. The methodology aims to make it possible to establish a data-driven decision making process based on monitored decay related to climate change. This monitoring campaign includes 45 medieval buildings distributed over the entirety of Norway. Thirty-five of these buildings are dated to before 1537 and include wooden buildings as well as 10 medieval churches built in stone while the remaining 10 buildings are situated in the World Heritage sites of Bryggen, in Bergen on the west coast of Norway, and in Røros, which is a mining town in the inland of the country. The monitoring is planned to run for 30 to 50 years. It includes a zero-level registration and an interval-based registration system focused on relevant indicators, which will make it possible to register climate change-induced decay at an early stage.

Standardization for indoor climate control in historic buildings has recently taken a new direction with standards and guidelines that focus more on decision processes than outcomes. The objective of the paper is to explore and discuss how standards can evolve to both fit and guide decision processes to facilitate a sustainable management of historic buildings. Interviews with engineers and heritage professionals in the Church of Sweden in combination with indoor climate monitoring were used to understand the technical and organizational context. The results show that the development of process standards solves some of the problems related to the conventional outcome-oriented approach by opening up for a wider set of solutions. However, available guidelines are difficult to apply and integrate in the existing management of churches. A stronger focus on strategic feedback and an increased use of local guidelines are suggested.

We proudly present the postprints of the third International Conference on Energy Efficiency in Historic Buildings, held in Visby, Sweden September 26th to 27th, 2018. The conference was organized jointly by the Swedish Energy Agency, Uppsala University and the Swedish National Heritage Board as part of their collaboration in the Swedish national research program on energy efficiency in historic buildings. The Region of Gotland kindly sponsored the conference dinner. There were close to one hundred abstracts submitted to the conference. We gratefully acknowledge the contributions from the Scientific Committee in the review process. Our thanks to Lisa Nilsen who has been the conference coordinator and editor of the papers, Susanna Carlsten who has been in charge of information and conference planning and Alice Sunnebäck who finished the layout of the papers and the report as a whole. The organizing committee for EEHB2018, Tor Broström Uppsala University Jörgen Sjödin Swedish Energy Agency Camilla Altahr-Cederberg Swedish National Heritage Board

Technical characteristics and cultural values affect the possibility of saving energy in the historic building stock. The issue has been addressed and studied in monumental buildings. For the majority of historic buildings, defined in this research as traditional constructions built before 1945 when the building sector became more industrialised, there is still a need for further studies. In order to study a large building stock it is necessary to make generalisations. To break down the stock into a few statistically representative categories is one way of doing that. The aim of this article is to present the development of a method to categorise a historic building stock with the ability to identify the potential for energy saving and preservation of cultural values. By studying building categories and typical buildings in detail the results can be extrapolated to represent a large building stock. The method for categorisation is done in three steps: building inventory, categorisation and selection of typical buildings. The inventory is when data on the building stock is gathered and compiled. This is necessary in order to have a sound statistical basis for the following steps of the method. The categorisation is done by dividing the buildings in groups based on their basic characteristics; for example size and number of adjoining walls. A delimitation is done, if necessary, in order to exclude atypical buildings. Typical buildings from each category are then selected by letting the medium values within the categories decide the characteristics of the typical buildings. Other characteristics such as age, use, construction type etc. can be determined for the typical buildings and motivated statistically based on the data in the inventory. A case study has been carried out on the historic building stock in the town Visby in Sweden, a UNESCO World Heritage Site. When applying the method for categorisation on the buildings built before 1945 in Visby the results show th

Intermittent heating, common in churches, requires higher heating power than steady state heating. With respect to energy use and preservation aspects, the heat up time should be short. Systems for intermittent heating are often designed using rule of thumb estimates or inadequate steady state calculations. This paper presents a method to relate heating power and heat up time for a specific building where thermal characteristics of a building are determined using a step response test.

The paper draws from the general literature on energy efficiency and historic buildings to explain the importance and potential of user-driven energy efficiency in historic buildings. It is the first review that places the user as a central object of study in the research field of historic buildings and energy efficiency. Relevant interdisciplinary topics and research results that make up the core of the field are presented and discussed in relation to user behaviour and its impact on energy consumption. The paper also investigates how user behaviour aspects can be integrated in a procedural approach to energy refurbishment in historic buildings. Research and experience from the building stock in general clearly shows how a user's awareness and behaviour, such as choice of temperature, zone heating and controlled airing, can have a significant effect on energy demand yet have no physical impact on the building. However, this has not received enough attention with regards to the historic building stock, where many physical energy efficiency measures can have negative impacts on the historic qualities of the building. Modification of user behaviour can therefore be a way not only to reduce energy demand but also to minimise the physical impact of increasing energy efficiency on historic buildings. The paper concludes that the current research agenda on historic buildings and energy efficiency has broken much ground but remains focused more on technical solutions than bottom-up user perspectives. Two main topics are identified as key barriers and future research fields: First, energy performance modelling is identified as a general barrier to developing sustainable strategies that promote user impact in historic buildings. Accurate energy modelling of historic buildings is a complex field reliant on the thermal interplay between user-building and building-district. Improved knowledge and intensified research is necessary to avoid distorted energy modelling results and

Climate change is expected to result in a warmer and more humid climate in northern Europe. Historic buildings with none or primitive climate control will face higher risk of bio-deterioration – mainly due to mould, rot and insects. There is a lack of experience of how different methods for energy efficient indoor climate control compare to each other in practical applications. The objective of this study was to evaluate and compare the relative performance of conservation heating, dehumidification and adaptive ventilation in a historic building. The investigation was carried out during three years at Skokloster, an unheated Baroque castle in Sweden suffering from problems due to high indoor relative humidity. The results show that the initial draught proofing of the rooms had a positive effect on the indoor climate which reduced the need for active climate control. Dehumidification was the most energy efficient method

Indoor climate and user satisfaction were analysed by field measurement and a questionnaire in 67 traditional rural houses in Estonia, Finland and Sweden. Our findings showed that the indoor climate in all the investigated historic rural houses needs improvement. The room temperature was mainly too low during winter. Leaky houses had also a larger vertical temperature difference. The relative humidity in the unheated and periodically heated houses was high during winter and caused risk for mould growth in 17% of all houses and 33% of unheated houses. Significant differences of indoor humidity loads in different houses were revealed depending on the living density and usage profile. During the winter period, the design value of moisture excess was 4-5g/m(3) and the average moisture load was 2-3.5g/m(3). The indoor humidity load in historic houses was similar to that in modern houses. The results of the questionnaire showed that main problems were related to unstable or too low temperatures. At the same time, inhabitants rated the overall indoor climate as healthy and no statistically important relations were found between average indoor temperature and complaints about too cold or too warm indoor temperatures.

Old medieval churches hold objects of great historical and cultural value: organs, altars, paintings. But they have no systems for indoor climate control or the church may be heated only at services. These conditions are inadequate for the preservation of cultural heritage. The objective of this paper is to assess an adaptive ventilation (AV) solution in a church for reduction of the relative humidity (RH) in an unheated church to prevent mould growth and disintegration of wooden parts. The operation principle of the system is to ensure ventilation in the church when water vapour content in the outdoor air is lower than that indoors, to lower the RH in the church. A case study in Hangvar Church in Gotland, Sweden, was conducted to test the performance of AV to reduce the RH in the church. Field measurements showed that AV has a positive impact on the indoor RH of the church. During the measurement period without climate control, the RH in the church was higher than 70% of 98% of the time; with AV, the indoor RH was higher than 70% only 78% of the time. Building simulation was carried out to test the performance and energy consumption of AV under different conditions. The simulations showed that auxiliary heating and airflow rate both have high impact on the system performance. The higher the heating power, the more effective the system is; thus, lower airflow rates are needed. Infiltration has also high impact on the system performance: the lower the infiltration rate, the better the AV performance is.

Spara och bevara

Buildings account for 40% of total energy consumption in the European Union, yet at the same time they have considerable energy saving potentials. Historic buildings should be treated different from contemporary ones when it comes to energy improvements. The specifications which underline historical, sociocultural and architectural values require certain care during realization of energy saving implementations to sustain these values. The purpose of this study is to demonstrate how the energy efficient retrofitting in historic buildings should be managed in a transdisciplinary approach with a case study conducted on the historic building in Izmir-Turkey. A detailed building energy simulation tool was used to determine the impacts of energy efficient retrofits. The actual energy consumption of case building was based on the utility bills regarding electricity and heating fuel consumption. Building energy simulation tool was calibrated by comparing the measured and simulated indoor air temperatures and total energy consumptions. The inappropriate retrofits, which contradict to the cultural heritage values, were eliminated with a transdisciplinary approach. Later appropriate retrofits were gathered into three packages to evaluate their effects on the energy consumption. The results show that energy saving of more than 34% can be obtained without damaging the heritage values. (C) 2015 Elsevier B.V. All rights reserved.