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• This paper presents a unique change-point model based on selected time periods. • Time-dependent variations in climate and user behavior are central in the selection of time periods. • The model allows for differentiation between thermal power characteristics. • The selected time period for prediction of Q total corresponds to the highest R2 value, 0.70. The building and service sector accounts for nearly 40% of total energy use in Sweden. The existing, historic building stock accounts for large part of this energy use and comprises an important part of the national pursuit to increase energy efficiency. One main problem for decreasing energy use in the existing building stock is the lack of data describing thermal performance characteristics. This paper presents a novel development of the change-point model for predicting the thermal performance of buildings using selected time periods based on time-dependent variations in climate and user behavior. The predicted thermal power characteristics include total specific heat losses (Q total), energy use for hot water circulation (HWC) and hot tap water (HTW), and balance temperature. A residential district with 73 historic buildings in Linköping, Sweden, has been used as the study object. The developed model is shown to be effective and robust for describing building thermal performance. The average R2 was 0.70 for predictions of specific heat losses. The sensitivity analyses conclude that the selected time steps and months correspond to the highest R2 value. The average variation width for prediction of the balance temperature is 0.9 °C for buildings in the interquartile range based on a three-year comparison of hourly heating power supply data. Moreover, from a property owner perspective, the model is shown to be useful for identifying deviating thermal power characteristics and can easily be used to get an overview of a district. [ABSTRACT FROM AUTHOR]

Many studies have highlighted the importance of retrofitting to mitigate the energy use of building stocks. An important step in the development of renovation strategy and energy conservation advising is to gather information of the energy performance of the existing buildings. However, renovation strategies must also consider the socio-economic challenges associated with the cost of energy retrofitting. This paper describes the development of an energy atlas of the multifamily building stock in Sweden for visualizing and analyzing energy use and renovation needs. The atlas has been developed using Extract Transform and Load technology (ETL) to aggregate information on the energy performance, building ownership, renovation status, and socio-economic status of inhabitants from various data sources. The atlas can visualize the energy use and renovation status of multifamily buildings in 2D maps and 3D models, displaying data for either individual buildings or aggregated data on spatial scales ranging from 250 × 250 m squares through district and municipality to county areas. A demonstration of its use on national and city scales indicates that energy retrofits of multifamily buildings reaching a service life of 50 years can reduce the energy use of the existing building stock by up to 50% relative to 1990. However, costs associated with renovation and energy retrofits of multifamily buildings can be problematic, especially in economically weak suburbs. A good understanding of past and future renovation needs and socio-economic consequences is important in the development of a sustainable national renovation strategy. [ABSTRACT FROM AUTHOR]

The cost-optimal level of energy performance for buildings shall be identified according to the European directive of 2010. The Swedish building stock needs comprehensive knowledge and an overall strategy for the cost-optimal level of renovation. This paper studies the contribution of Swedish climate zones to the cost-optimal level of renovation on a multi-story residential building in Sweden from the building owner perspective. The building space heat demand is simulated for four Swedish climate zones. The net present profit (NPP) method is defined and used in this study in order to analyze the cost-optimal level and the cost-effective renovation of building envelope components (e.g., attic floor, basement walls, exterior walls and windows). The implication of different discount rates is studied, as well. The results show that the optimum renovation of the building envelope offers 51% more energy savings for space heating when the building is in a northern climate zone compared to a southern zone. The study suggests that different renovation strategies for the building stock renovation need to be identified, separately, for each climate zone. The NPP analysis identifies the minimum required investment and maximum achievable energy savings that are needed to have a cost-effective renovation. The broad range of studied climate zones provides the opportunity to apply the obtained results to other climate zones by either interpolation or extrapolation of NPPs for the buildings with similar characteristics. [ABSTRACT FROM AUTHOR]

• Development of energy signature method using data before and after deep renovation of a multi-family building. • Comparison of the proposed energy signature method with building energy simulation program IDA ICE. • Prediction of domestic hot water circulation losses using energy signature method. • Prediction of heat loss coefficient using energy signature method. 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. [ABSTRACT FROM AUTHOR]

The National Environmental Objectives (NEOs) adopted by Swedish Parliament in 2001 and proclaimining that major environmental problems should be solved within a generation are often portrayed as good practice of a concrete yet visionary sustainability strategy. In this paper we summarize one and a half decade of the NEOs' experience for the international audience. The NEOs were based on an eclectic mixture of conceptual reasoning, most importantly the Management by Objectives concept and the notion of a policy deriving its authority and legitimacy from scientifically established ‘natural laws and limits’. The 16 NEOs fall into two groups. The first group is a positive reformulation of existing environmental problems based on well established scientific evidence. While they have scientific authority and can be operationalized and enforced through standards they are hardly visionary, strategic or capable of responding to emerging threats. The second group contains utopian landscape goals which are more visionary but also more difficult to operationalize, especially for local authorities which play major part in the implementation of the NEOs in Sweden. We argue that the system that mixes these two sets of goals based on two different paradigms of sustainable development inherits the weaknesses of both and the strengths of neither. The NEO system lacks the hierarchical and scientific authority potentially possible for scientific goals and at the same time fails to provide for learning, mobilisation and consensus-building power of utopian landscape goals. It has been too fuzzy to be implemented in a top-down way and yet too rigid to enable bottom-up action. A more effective approach would be to separate these two sustainability governance approaches into complementary but distinct systems. [ABSTRACT FROM AUTHOR]

In order to tap the energy saving and climate mitigation potential of buildings, transaction costs of implementing energy efficient technologies need to be better understood and ultimately reduced. The objective of this paper is to identify and analyze the nature and scale of transaction costs resulting from the application of the passive house concept in energy efficient renovations. Related conceptual choices are also discussed. This study explores learning strategies as a potential to reduce transaction costs. It focuses on transaction costs borne by building owners and building developers in the planning and implementation phases of a passive house-oriented renovation in Sweden. Results reveal three main sources of transaction costs: due diligence, negotiations and monitoring. The analysis shows that transaction costs are non-negligible and for individual cost sources the scale can be three times higher than for conventional renovations. To reduce transaction costs, various learning strategies such as study visits, demonstration projects, new forms of meetings and new channels of (written) information were found. These strategies have the potential to half transaction costs of future renovation projects. [ABSTRACT FROM AUTHOR]

Rapidly growing energy use in the building sector is considered a serious problem by both the European Union (EU) and Sweden. Reducing energy demand in the building sector is important for Sweden in order to reach national energy goals for reduced energy use and CO 2 emissions in the future. This project aims to find energy efficiency potential in multifamily buildings in the Gävleborg region, which is a cold climate region in Sweden. Measurements and simulations have been made on eleven multifamily buildings from the whole region. The results include different energy efficiency measure packages, profitability analysis of individual measures and packages, and primary energy use analysis. The paper also includes CO 2 emissions reduction analysis based on different methods. The project shows that the multifamily buildings in the Gävleborg region have good potential to reduce their energy use by more than 50%, which in turn will contribute to 43% primary energy reduction and 48% CO 2 emissions reduction. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the Energy, Carbon and Cost Assessment for Building Stocks (ECCABS) model, which is a bottom-up model to assess energy-saving measures (ESM) and carbon dioxide (CO2) mitigation strategies in building stocks. The model is based on a one-zone hourly heat balance that calculates the net energy demand for a number of buildings representative of the building stock and an additional code for the input and output data. The model generates results in terms of net and delivered energy, associated CO2 emissions, and the costs of implementing different ESM. The results are extended to the entire building stock by means of weighting factors. Empirical and comparative validations of the heat-balance modelling of single buildings are presented. The building stock modelling is validated against the current Swedish residential stock, for which the results of the modelling are in agreement with the statistical data. Using the model to assess a number of ESM reveals that the energy usage of the Swedish residential sector can be reduced by 55% and the associated CO2 emissions can be reduced by 63%, with most of the ESM being cost–effective. The applicability of the model to countries other than Sweden is under investigation. [Copyright &y& Elsevier]

Abstract: Passive Houses have gained popularity the last 10years as a way of improving the energy efficiency in the housing stock. The combination of a highly insulating building envelope and large solar heat gains summertime can, however, result in excessive temperatures. The aim of this paper is to evaluate a comfort cooling strategy for attaining good indoor climate summertime while maintaining good energy efficiency. The studied strategy is a night cool storage with phase change material (PCM). To evaluate this, a Matlab code was used for the analysis of climate files along with the thermodynamical properties of PCM storages and then used with IDA Indoor Climate and Energy for building simulations. The building model is based on an actual Passive House in the district of Lambohov in Linköping, Sweden, where continuous logging of temperatures are available. Without comfort cooling the simulations show excessive temperatures summertime, which is consistent with the field measurements from the actual house. The results show that the PCM can remove a substantial share of the degree hours with excessive temperatures. [Copyright &y& Elsevier]

Literature and experience show that there are large discrepancies between the calculated and measured building energy usages, where user-related parameters are significant factors with regard to energy use in low-energy buildings. Furthermore, the difficulties encountered when quantifying these parameters compound these discrepancies. The main aim of this study was to provide feedback that would help the building industry and research communities to predict more accurately the impact of the user-related parameters on energy performance. The results of the study would, subsequently, contribute to minimizing the discrepancies between calculated and measured energy use. This article analyses simulated building energy use based on randomly chosen combinations of measured user-related parameters in three recently built low-energy schools in Sweden. The results show that energy performance can span from 30 to 160 kWh/(m² y) simply by varying the combination of previously measured user-related parameters in building energy simulations. The study shows that the set points for indoor air temperatures during the heating season and the energy required to run a demand-controlled ventilation system have an extensive influence, while tenant electricity use has a slightly lower influence on building energy use. Variations in occupancy rates and energy for hot water usage have the smallest influences on building energy use. [ABSTRACT FROM AUTHOR]