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This article presents a new methodology to disaggregate the energy demand for space heating (SH) and domestic hot water (DHW) production from single hourly smart heat meters installed in Denmark. The new approach is idealized to be easily applied to several building typologies without the necessity of in-depth knowledge regarding the dwellings and their occupants. This paper introduces, tests, and compares several algorithms to separate and estimate the SH and DHW demand. To validate the presented methodology, a dataset of 28 Danish apartments with detailed energy monitoring (separated SH and DHW usage) is used. The comparison shows that the best method to identify energy demand data points corresponding to DHW production events is the so-called “maximum peaks” approach. Furthermore, the best algorithm to estimate the SH and DHW separately is a combination of two methods: the Kalman filter and the Support Vector Regression (SVR). This new methodology outperforms the current Danish compliances typically used to estimate the annual DHW usage in residential buildings.

Extensive research demonstrates the importance of user practices in understanding variations in residential heating demand. Whereas previous studies have investigated variations in aggregated data, e.g., yearly heating consumption, the recent deployment of smart heat meters enables the analysis of households’ energy use with a higher temporal resolution. Such analysis might provide knowledge crucial for managing peak demand in district heating systems with decentralized production units and increased shares of intermittent energy sources, such as wind and solar. This study exploits smart meter heating consumption data from a district heating network combined with socio-economic information for 803 Danish households. To perform this study, a multiple regression analysis was employed to understand the correlations between heat consumption and socio-economical characteristics. Furthermore, this study analyzed the various households’ daily profiles to quantify the differences between the groups. During an average day, the higher-income households consume more energy, especially during the evening peak (17:00–20:00). Blue-collar and unemployed households use less during the morning peak (5:00–9:00). Despite minor differences, household groups have similar temporal patterns that follow institutional rhythms, like working hours. We therefore suggest that attempts to control the timing of heating demand do not rely on individual households’ ability to time-shift energy practices, but instead address the embeddedness in stable socio-temporal structures.

Technical research indicates that buildings can be used for short-term heat storage to peak-shave daily profiles in district heating. Increasing the energy flexibility of buildings implies new relations between demand and production – newly defined roles between residents and heating professionals. Heating professionals' understanding of residents is an important precondition for how these roles can be changed. To investigate this empirically, this paper reports from three future workshops where professionals from Danish district heating utilities, municipalities, energy companies and housing organisations discuss possibilities for including residents more actively in flexibility generation and more generally in district heating systems operation. The analysis focuses on the importance professionals ascribe to residents compared to other actors, the vocabulary professionals use to describe residents, and, most importantly, the rationales professionals ascribe to residents. Inspired by the notion of sociotechnical imaginaries, our analysis shows how the professionals imagine residents and ascribe rationales of autonomy, economy, comfort, involvement and sustainability to them. The professionals emphasise the first three rationales in particular. The conclusion points to the negative consequences such imaginaries may have for the future development of flexible district heating and proposes experimenting with various collaborative forms for engaging residents and professionals.

Much effort has been put in tightening the building regulations. Though, the energy usage for domestic hot water stayed unchanged constituting a bigger share of the energy pie over the years. Due to the cost, timeframe, and workload associated with instrumentation and installation, the vast majority of the DHW measurements are limited to the household level. This paper introduces a high resolution measuring technique for DHW consumption and its application in a single family house. By applying this technique, we are able to measure the duration, flow and temperature of each water draw event in the house and thus create both the temporal and spatial DHW consumption profiles. The results indicated that the duration of draws varies significantly between tapping places, i.e. the draws in the shower and in the kitchen have an average duration of 300 sec. and 20 sec., respectively. The high resolution metering system was able to record the inefficient use of DHW, at periods when the water temperature was not meeting the users’ requirements, e.g. the wasted energy at the shower depending on the usage patter varies between 25% and 42%. The measured temperature range of DHW in the household is between 52°C (kitchen) and 21°C (sink in utility room).

Prosumers have a different interaction with the distribution network in comparison with traditional consumers. They have a bi-directional power exchange with the grid, meaning they receive from as well as deliver electricity to the network. The emergence of prosumers is expected to challenge the way network operators control the residential low-voltage (LV) distribution networks. Commonly, the metering of received and delivered electricity at the residential level is conducted on 1-hour basis, thus only hourly load/generation profiles are available for the system operators to conduct the power system impact analysis. Yet, it is relatively difficult to have an accurate prediction of the real system performance if the intra-hour phenomena are not considered. A better estimation requires employment of higher temporal resolution profiles during the power system studies. To address these challenges, which future smart cities and communities might face, this paper presents a methodology for generating 1-minute load profiles based on the hourly readings from smart meters. Secondly, it demonstrates gain in information about LV network by employing the high resolution profiles for power system impact analysis. Finally, it highlights the problems of smart residential networks with high share of prosumers for two LV network scenarios during winter and summer weeks.

In Europe, one of the most sustainable solutions to supply heat to buildings is district heating. It has good acceptance in the Northern countries, a low-carbon footprint, and can easily integrate intermittent renewable energy sources when coupled to the electrical grid. Even though district heating is seen as a vital element for a sustainable future, it requires extensive planning and long-term investments. To increase the understanding of the district heating network performance and the demand-side dynamics of the connected buildings, several countries, including Denmark, have installed smart heat meters in different cities. In that context, this paper presents several methodologies to analyze the datasets from the smart heat meters installed in a small Danish town. The first method is concerning data curation to remove the anomalies and missing data points. The second method analyses measured variables (heat consumption, outdoor temperature, wind speed, and global radiation) to acquire new knowledge on the building characteristics. These results were compared with the values given by the energy performance certificates of a smaller sample of 41 households. Finally, to communicate and visualize the analysis outputs in a user-friendly way, an interactive web interface tool has been created.

For a very long time activities related to efficient domestic hot water (DHW) production and distribution have been neglected and left behind due to an insignificant share in total energy use for buildings. It is in recent years that DHW has emerged as one of the key energy factors in the total energy use in buildings and its share is continuously increasing as energy use in other segments is continuously decreasing, for example space heating, ventilation, and energy for lighting. It becomes suddenly undeniable that efforts in the field of energy-efficient DHW must be strengthened, and as such, there is increased activity in the field. However, the work reported is very dispersed and fragmented. The objective of this review article is to collect and present recent works related to improve performance of a DHW system in terms of energy. The scope and content of the paper aims to address the topics of high relevance to the field, these are shift towards the new situation in which DHW becomes a significant energy use responsible factor in buildings, distribution and weighting of losses related to DHW systems and purpose of DHW use. The article focuses on novel actions to obtain energy-efficient DHW in the following domains: DHW production, DHW distribution and circulation, wastewater heat recovery, and control strategies. The article finishes with conclusions.

International audience; This paper aims to visualize how the planned electrification of heat demand together with the utilization of energy flexibility in buildings will influence the performance of local electricity network. Thereby, the work contributes to the research on smart energy system in the residential sector. The flexibility service is provided by two demand-side-management strategies a) activation of the thermal mass to modulate load profile of a heat pump, b) control of household appliances' starting times. Three configurations of load mix in the local electricity network are investigated: a) domination of non-renovated houses, b) with equal share of high and low heat demand houses, c) domination of energy efficient houses. The model is soft-coupled and anchored in existing low voltage (LV) network and existing residential buildings. The energy flexible buildings enhance the LV network performance, by decreasing the afternoon peaks, without compromising the occupants’ thermal comfort. The highest impact is for the LV network dominated by energy efficient houses. There are also new challenges, namely the newly created peak loads and transformer overloading during night time. It is a consequence of uniform price signal sent to all flexible customers and electrification of heating demand without parallel improvement of energy performance.

District heating has been found to be a key component of future and reliable smart energy grids comprising 100% of renewable energy sources for countries with dominant heating season. However, these systems face challenges that require a deeper understanding of the coupling between the distribution networks and the connected buildings, to enable demand-side management and balance the intermittence of renewables. In recent years, many smart energy meters have been installed on the heating systems of Danish dwellings connected to district heating, and the first yearly measurement data sets of large building clusters are now available. This article presents the methodology for the pre-processing and cluster analysis (K-means clustering) of a one-year-long smart energy meter measurement data from 1665 Danish dwellings connected to district heating. The aim is to identify typical household daily profiles of heat energy use, return temperature, and temperature difference between the supply and the return fluid. The study is performed with the free software environment “R”, which enables the rapid extraction of information to be shared with professionals of the building and energy sectors. After presenting the preliminary results of the clustering analysis, the article closes with the future work to be conducted on this study case.

Denmark aims to be independent of fossil fuels in the country's energy production by 2050. One of the initiatives to reach the decarbonization goal is the digitalization of the energy sector, specifically the roll-out of smart meters in the buildings connected to the district heating network. As a result, it allowed having better insights into the dynamics of the heating loads of the demand side. However, these meters often record the total energy usage without distinguishing between the energy use for space heating (SH) and domestic hot water (DHW). Additionally, the metered data have hourly resolution, which prevents the detection of short DHW usage. To tackle this limitation and gain valuable information on the buildings' heating patterns, this paper presents a new methodology to estimate the energy use for SH and DHW from total measurements in residential buildings. The method employs a combined smoothing algorithm with a support vector regression to estimate the energy use for SH from outdoor conditions. The energy use for DHW is calculated a posteriori by the difference between the total measurements and the estimated SH energy. The advantage of this technique is the ability to be applied in hourly-resolution data while only requiring local weather measurements, making it a tool to be utilized in different scenarios. This method is validated with three different sets of building cases. The first dataset consists of 28 apartments in Denmark, where the measurement resolution is coarse at 1 kWh. This case focuses on determining the method's accuracy in single-family dwellings when their measurements are truncated. The second dataset set of apartments is located in a 5-story building in Switzerland. In this case, the objective is to test the method's accuracy when analyzing aggregated measurements of all dwellings in the building. The third dataset includes hourly readings from customers connected to a DH network in Italy. In this case, the objective is to test the method's application to other building typologies (i.e., historical buildings). Because these three cases are located in different countries, this validation study also tests the method's robustness to the variability of users, locations, and heating system types.

There is little specific knowledge of actual temperature conditions in buildings. This paper contributes with results from a detailed long-term monitoring campaign of temperature conditions in 17 households. Furthermore, these measurements are combined with qualitative interviews with 22 occupants in 16 households, on their heating practices. Implications for the assessment of the heat demand flexibility potential are discussed, and it is suggested that including occupants in future experiments can be a way to reach the full potential of buildings flexibility potential to a renewable energy sources dependent energy system. Quantitative data show that temperature conditions vary with time and space within each dwelling and between dwellings. In the same apartment, the temperature difference between spaces can be 7 K. The living rooms have the most homogeneous temperature distribution during 24 h period and the bedrooms most significant variations. Qualitative data indicate that aspects of: Activities performed by occupants; Caring for things, others and oneself; Comfort; Convenience; Natural and material surroundings affect occupants’ heating practices.

The share of the energy use for domestic hot water (DHW) in the total energy consumption of buildings is becoming more and more prominent. Depending on the building typology it varies between 20% to 50% of the total energy usage for old and new built single family house, respectively. The aim of this paper is to determine the energy losses in the DHW installation with division between: a) loss at the production point, b) loss in the distribution, and c) loss at the draw-off points using the results of the measurements of DHW consumption in two single family houses connected to district heating grid. The total Eloss for the two houses vary between 17% and 26%. For House 1, the production loss accounts for 8%, the pipe loss for 15% and loss at the draw off points for 3%. Moreover, the results shown that the layout of the house, in particular the placement of the bathrooms with showers or bath tubs has significant impact on the size of the distribution losses.

The focus on reducing buildings energy consumption is gradually increasing, and the optimization of a building’s performance and maximizing its potential leads to great challenges between architects and engineers. In this study, we collaborate with a group of architects on a design project of a new office building located in Aarhus, Denmark. Building geometry, floor plans and employee schedules were obtained from the architects which is the basis for this study. This study aims to simplify the iterative design process that is based on the traditional trial and error method in the late design phases and improve the collaboration efficiency. Monte Carlo Simulation method is adopted to simulate both the energy performance and indoor climate of the building. Building physics parameters, including characteristics of facades, walls, windows, etc., are taken into consideration, and thousands of combinations of these parameters are screened to find those can achieve the design criteria. The software Be15 and BSim are used as two-step solvers to process the calculation of energy consumption and indoor environment. A solution pool is then obtained for architects to choose from, see Fig. 2 and 3. All these solutions can fulfil the requirements and leaves additional design freedom for the architects. This study utilizes global design exploration with Monte Carlo Simulations, in order to form feasible solutions for architects and improves the collaboration efficiency between architects and engineers.

During recent years, the research in reduction of energy use in buildings has focused primarily on decrease of space heating needs, energy for ventilation and recently cooling, whereas domestic hot water (DHW) has been overlooked. In 2013, the energy use for DHW was estimated at 16% of total heat requirement in EU28 households, but in new energy-efficient buildings this share is documented to be around 40–50%. Generally, however, there is limited knowledge of DHW. This paper presents a simple methodology, which enables calculation of the mean hourly and the daily profiles of DHW demand from hourly values of the building total heat demand, and thus contributes to gaining a better understanding of the DHW usage. The method is validated with data from single-family houses and apartments and afterwards applied to dataset consisting of hourly total heat consumption readings from 38 single-family houses delivered by district heating. The method gives satisfying results when the DHW usage during summer is at least at the same level as the space heating demand, which is the case in apartments and in the energy-efficient houses. The standard deviation was used as preliminary classification criterion for deciding if the method can or cannot be applied. Two limits were found σ > 240 for apartments and σ < 800 for single-family houses.

As demand response and energy flexibility are often suggested as key principles to facilitate high levels of renewable energy sources into energy markets, different studies evaluated the potential impact of energy flexibility in buildings. Nonetheless, due to differences in definition and quantification methodologies for energy flexibility, comparing results between such studies is difficult. With a review and applied evaluation of existing definitions and quantification methodologies this paper aims at assessing the applicability, benefits and drawbacks of each quantification methodology. The conducted review shows that energy flexibility definitions found in the literature have their particularities despite sharing the same principle that energy flexibility is the ability to adapt the energy profile without jeopardizing technical and comfort constraints. The survey of quantification methodologies reveals two main approaches to quantify energy flexibility. A first approach quantifies energy flexibility indirectly using past data and assuming a specific energy system and/or energy market context. The second approach directly predicts the energy flexibility that a building can offer to the energy system in a bottom-up manner. While applications for both approaches were identified, this paper focuses on the latter. By applying methodologies that follow this second approach to a common case study, three common properties of energy flexibility were observed: i) the temporal flexibility; ii) the amplitude of power modulation; iii) and the associated cost.

The increasing global energy demand, the foreseen reduction of available fossil fuels and the increasing evidence off global warming during the last decades have generated a high interest in renewable energy sources. However, renewable energy sources, such as wind and solar power, have an intrinsic variability that can seriously affect the stability of the energy system if they account for a high percentage of the total generation. The Energy Flexibility of buildings is commonly suggested as part of the solution to alleviate some of the upcoming challenges in the future demand-respond energy systems (electrical, district heating and gas grids). Buildings can supply flexibility services in different ways, e.g. utilization of thermal mass, adjustability of HVAC system use (e.g. heating/cooling/ventilation), charging of electric vehicles, and shifting of plug-loads. However, there is currently no overview or insight into how much Energy Flexibility different building may be able to offer to the future energy systems in the sense of avoiding excess energy production, increase the stability of the energy networks, minimize congestion problems, enhance the efficiency and cost effectiveness of the future energy networks. Therefore, there is a need for increasing knowledge on and demonstration of the Energy Flexibility buildings can provide to energy networks. At the same time, there is a need for identifying critical aspects and possible solutions to manage this Energy Flexibility, while maintaining the comfort of the occupants and minimizing the use of non-renewable energy. In this context, the IEA (International Energy Agency) EBC (Energy in Buildings and Communities program) Annex 67: “Energy Flexible Buildings” was started in 2015. The article presents the background and the work plan of IEA EBC Annex 67 as well as already obtained results. Annex 67 is a corporation between participants from 16 countries: Austria, Belgium, Canada, China, Denmark, Finland, France, Germany, Ireland, Italy, The Netherlands, Norway, Portugal, Spain, Switzerland and UK. ispartof: Energy and Buildings vol:155 pages:25-34 status: published

Buildings are a key active element of the future Smart Grids with large shares of renewable energy, as they can provide flexible energy usage to help balancing power production intermittence. There is currently no consensus yet on how to quantify building energy flexibility. The various KPIs found in literature can be classified into 4 main categories: load shifting ability, power adjustment, energy efficiency and cost efficiency. Most of them use a reference scenario. Moreover, the envelope performance appears to be the most important parameter with regards to all aspects of building energy flexibility when using indoor temperature set point modulation. Buildings are a key active element of the future Smart Grids with large shares of renewable energy, as they can provide flexible energy usage to help balancing power production intermittence. There is currently no consensus yet on how to quantify building energy flexibility. The various KPIs found in literature can be classified into 4 main categories: load shifting ability, power adjustment, energy efficiency and cost efficiency. Most of them use a reference scenario. Moreover, the envelope performance appears to be the most important parameter with regards to all aspects of building energy flexibility when using indoor temperature set point modulation.

Buildings will play a significant role in providing a safe and efficient operation of the future energy system. The aim of this work is to investigate how typical cost-effective renovation packages contribute to energy consumption reduction as well as influence the energy flexibility in a Danish single-family from 1970s, and if simple rule-based controller can contribute in peak shaving strategy. By choosing the different renovation packages, the space heating demand can decrease between 34 - 64% and the flexibility time can increase between 200 – 500%. Depending on the cut-off period, the simple RBC of turning off the heating power can further reduce the heating consumption and contribute in reducing the morning load peak with small compromise on the thermal comfort level.

Intermittent energy resources challenge the ways in which the existing energy system operates. Studies suggest that residential buildings can provide a flexibility service for district heating (DH) systems. This technique involves load shifting by heating buildings to higher temperatures at times when energy is more readily available, thus diminishing heating needs at times of peak demand or when energy is scarce. Based on three Future Workshops (FWs) where DH professionals and other relevant DH stakeholders participated and discussed this topic, this paper reports on the extent to which these actors see energy flexibility as a realistic future development, and on what they see as key potentials and challenges in that regard. Preliminary results indicate that the mix of the actors and the specific local context greatly influence how this topic is understood, emphasizing the importance of including local context in investigations of energy flexibility. FW participants included representatives from DH companies, municipalities, building associations, technology developers, etc. The FWs were conducted at three different localities of Denmark: Copenhagen, Aalborg and Sønderborg, i.e. the national capital, a regional capital and a smaller city, respectively.

The objective is to present a high-resolution model of household electricity use developed based upon a combination of measured and statistical data. It is a bottom-up model, which uses the 1-min cycle power use characteristics of a single appliance as the main building block. The effect of parameters, such as the number of occupants and their attitude towards energy use is included in the model. Moreover, the model accounts for phenomena related to unexpected weather conditions and local/national events, e.g. TV shows. The main aim of model is to generate high-resolution household load profiles for investigation of flexibility potential of domestic appliances and network modelling. The model is validated with two datasets of 1-h and 5-min data from 89 to 16 households, respectively. The comparison between measured and modelled values indicates that model well captures the characteristics of domestic electricity load profiles on a daily as well seasonal basis. For high-resolution data, the model represents well the differences in demand between households of dissimilar size as well as the diversity of demand between households of the same size. For the individual household, the high-end power consumption is under-represented since the timing of peaks is more diverse in the model.

Night-time ventilation is a promising approach to reduce the energy needed for cooling buildings without reducing thermal comfort. The objective of the present paper is to determine how different emissivity of flooring influence the heat transfer in a room and the efficiency of night-time ventilation using displacement ventilation. Experimental work was conducted on the basis of the work performed by Artmann et al. (2009) in a similar previous study. An aluminum-foil floor cover was installed in a full scale test room. Experimental results obtained with aluminum flooring were compared to results obtained by Artmann et al. with a flooring consisting of expanded polystyrene (EPS). Results showed that the surface temperature of the floor decreased with decreasing emissivity. Mean convective heat fluxes were similar for experiments conducted with both EPS and aluminum-foil floor cover, but it was seen that the emissivity of the flooring affected the heat transfer ratio at the internal surfaces. The convective heat flux increased at the ceiling and decreased at the floor for experiments with aluminum flooring compared to the experiments with EPS floor. Temperature efficiency was slightly higher for experiments with aluminum flooring than for EPS floor. As the efficiency was only a bit higher with an extremely low emissivity of the floor cover, it was concluded that the influence of different emissivity of floor covers can be neglected concerning efficiency of displacement night-time ventilation.

When designing new buildings a Double-Skin Facades (DSF) concept is recurrently discussed as an energy saving solution. There is a strong demand for a tool, which could estimate the energy performance of a DSF building in an early design stage, in order to assess whether it fulfills the Energy Performance Building Directive. Therefore, the Bestfacade Project Group has developed the Simple Calculation Method (SCM).In this paper the calculations of DSF performance using SCM are compared against experimental data gathered in a full-scale model for three data-sets from different periods of the year. The SCM is recommended for assessing a seasonal DSF performance, however, it gives more reliable results if SCM is applied for shorter periods. Detailed calculation results tend to differ from the measurements, mainly due to overestimating the cooling demand. The validation described in this paper led to conclusions regarding possible improvements of SCM. When designing new buildings a Double-Skin Facades (DSF) concept is recurrently discussed as an energy saving solution. There is a strong demand for a tool, which could estimate the energy performance of a DSF building in an early design stage, in order to assess whether it fulfills the Energy Performance Building Directive. Therefore, the Bestfacade Project Group has developed the Simple Calculation Method (SCM).In this paper the calculations of DSF performance using SCM are compared against experimental data gathered in a full-scale model for three data-sets from different periods of the year. The SCM is recommended for assessing a seasonal DSF performance, however, it gives more reliable results if SCM is applied for shorter periods. Detailed calculation results tend to differ from the measurements, mainly due to overestimating the cooling demand. The validation described in this paper led to conclusions regarding possible improvements of SCM.

Today’s HVAC systems in the building sector become more and more complex in order to fulfill the increasing standard of the indoor environment, which typically have many components, sub-systems, and controls. Commissioning is a quality-oriented process to verify and document that the performance of buildings and HVAC systems fulfill the defined objectives and criteria. This study demonstrates the commissioning process in a campus building in Denmark. By analyzing the monitored date from BMS and on-site measurements, some fault operations and controls in the HVAC systems are identified, for example, improper setpoint for heating and ventilation, fault location of temperature and CO2 sensors, too high return temperature for district heating, etc. A building simulation model is developed and validated in order to test the optimization strategies and evaluate the energy conservation potential. An energy saving ranges from 20%-42% is realized after the implementation of the optimization strategies.

Previous studies showed that magnetocaloric heat pump,based on the active magnetic regenerator technology,can be used for space heating of low energy buildings.This innovative solution has performances comparableto conventional vapour-compression systems. However,magnetocaloric heat pumps have limited temperaturespan between heat source and heat sink. Thatcompromises their use for high temperature spanpurposes such as domestic hot water production. Toovercome this issue, the authors suggest a cascadingconfiguration of several magnetocaloric heat pumps. Theresults of the current numerical study show that suchcascading network can provide for the hot water needs ofa single-family house with coefficient of performancewhich is similar to conventional heat pump systems.

The worldwide CO2 emission mitigation efforts, the growing energy resource shortage and the fact that buildings are responsible for a large share of the world’s primary energy use drives research towards new building concepts, in particular Zero Energy/Emission Buildings (ZEBs). Unfortunately, the lack of a common understanding for this new type of building results in most countries to have their own, unique approaches. This paper presents the northern (Danish, Finish, Norwegian and Swedish) understanding of ZEBs and gathers together information related to ZEBs in these countries. Generally, we may observe a correlation between the zero energy/emission building approach adopted by a country and this particular country’s utility grid characteristics. Moreover, it is to be noted that the ZEB concept is not well defined at the national level in northern Europe and that all of the participating countries are still to adopt a national definition for these types of buildings. This results often in more than one understanding of ZEBs in each country. This study provides a concise source of information on the north European understanding of zero energy/emission buildings. It puts forward a number of similarities among the four studied approaches while highlighting that each country adopts a slightly different ZEB concept depending on its particular realities. This work may be viewed as a useful input to the coordination of sustainable building research in northern Europe and as a good source of information on different possible approaches towards ZEBs. The worldwide CO2 emission mitigation efforts, the growing energy resource shortage and the fact that buildings are responsible for a large share of the world’s primary energy use drives research towards new building concepts, in particular Zero Energy/Emission Buildings (ZEBs). Unfortunately, the lack of a common understanding for this new type of building results in most countries to have their own, unique approaches. This paper presents the northern (Danish, Finish, Norwegian and Swedish) understanding of ZEBs and gathers together information related to ZEBs in these countries. Generally, we may observe a correlation between the zero energy/emission building approach adopted by a country and this particular country’s utility grid characteristics. Moreover, it is to be noted that the ZEB concept is not well defined at the national level in northern Europe and that all of the participating countries are still to adopt a national definition for these types of buildings. This results often in more than one understanding of ZEBs in each country. This study provides a concise source of information on the north European understanding of zero energy/emission buildings. It puts forward a number of similarities among the four studied approaches while highlighting that each country adopts a slightly different ZEB concept depending on its particular realities. This work may be viewed as a useful input to the coordination of sustainable building research in northern Europe and as a good source of information on different possible approaches towards ZEBs.