All publications from the ZEN Research Centre are financially supported by the Research Council of Norway through its funding scheme for Centres for Environment-friendly Energy Research (grant no. 257660).

Our latest scientific publications

ZEN Report 20,

Calculation of Key Performance Indicators of Energy and Power in Ydalir

Ydalir is the name of a development area located northeast of the centre of Elverum. The area is one of
the pilot areas in FME ZEN with ambitions of becoming a Zero Emission Neighbourhood (ZEN). At
the end of the construction period the area will have a new school, a kindergarten, and about 700
residential units. There are high ambitions for the development of Ydalir. For Ydalir to fulfil the ZEN
definition, it must be energy efficient, and the emissions from the area must be reduced. The emission
reductions in Ydalir will be achieved through building according to the Norwegian passive house
standard (NS 3700/NS3701), by using district heating, and by installing photovoltaic (PV) solar panels.

The development of the definition of a Zero Emission Neighbourhood (ZEN) and the development of
assessment criteria and key performance indicators is an ongoing process that will last throughout the
program period of FME ZEN. This work will enable an assessment of the performance of the ZEN pilot
areas. Based on the draft for the ZEN definition, the assessment criteria and KPIs (per 2019) can be
divided into the following categories: GHG Emissions, Energy, Power, Mobility, Spatial qualities,
economy and innovation.

Constructing Ydalir as a ZEN will have positive impacts on energy consumption, the peak load,
and the utilization of the local electricity grid.

The purpose of this report is to test the indicators on energy and power on a ZEN-pilot in the planning
phase. The suggested energy KPIs and power KPIs have been tested for Ydalir for the year 2035. It is
assumed that the area will be fully operational by this time. Two scenarios have been created for Ydalir,
2035: the first scenario represent the current expectations for the pilot area and is called the «ZEN
Scenario». The second scenario represent the reference project, or the «Business as usual» (BAU) case
for the development of Ydalir. This is called the «Baseline Scenario». The KPIs for Energy and Power
have been calculated for Ydalir for both scenarios.

This analysis shows that the KPI net energy demand can be reduced by 27 %, the total import of energy
can be reduced by 30%, and the combined peak load for electricity and heating can be reduced by 24%
in the ZEN-scenario compared to the Baseline Scenario.

Annual energy use and emissions from the use phase can be significantly reduced if the development
turns out as expected, if all developers follow the master plan, and if the use of transport by car is reduced
as expected. The testing of the KPIs used in ZEN within the categories Energy and Power shows that
there is a need for further work on system boundaries, the reference scenario, and finding standard

Involved ZEN-partners in this study have been SINTEF, Elverum Vekst, and Elverum municipality.

Matthias Haase, Nicola Lolli and Kari Thunshelle (2020) Renovation concepts for residential buildings
ZEN Report 19,

This study looks at the challenges and opportunities in the deep energy renovation market with prefab elements. An analysis of 39 European projects was conducted, and the results where structured in three topics.

Nuijten, Anne (editor) (2020) Innovasjonsarbeid i FME-ene
ZEN Memo 23,

Denne memoen er resultatet av arbeidet i 2019 og beskriver for FME-ene ZEN, NTRANS, HydroCen, CINELDI, HighEFF, NCCS og SUSOLTECH hvordan FME-ene jobber med innovasjon og hva resultatene er så langt.

Moazami, Amin (2019) Climate Robust Buildings: Towards Buildings with a Robust Energy Performance Under Climate Change
PhD thesis,

Yu, Xingji; Georges, Laurent; Knudsen, Michael; Sartori, Igor; Imsland, Lars Struen (2019) Investigation of the Model Structure for Low-Order Grey-Box Modelling of Residential Buildings
Proceedings of Building Simulation 2019: 16th Conference of IBPSA,
8 p.,

All our publications

ZEN Memo 10,

In order to evaluate different technical solutions for zero emission neighbourhoods, IDA ICE models of single-family houses representative for the Norwegian building stock has been developed. This memo describes the procedure for how they have been modelled.

Ø. Rønneseth, I. Sartori

ZEN Report 8,


This report is a part of Work Package 4 Energy Flexible Neighbourhoods. The goal for WP 4 is to develop knowledge, technologies and solutions for design and operation of energy flexible neighbourhoods.

4th generation district heating is evaluated as a sustainable solution for covering the heating demand in Zero Emission Neighbourhoods and reducing the strain on the electricity grid. There are, however, some technical challenges that must be solved before it is introduced. One of them is to determine how low the supply temperature could be in different building types, which again will determine the minimum district heating supply temperature. This report is evaluating the minimum supply temperature in Norwegian apartment blocks based on effects of improving the thermal envelope and reducing the temperature levels for the heating system. The analysis is based on building simulation and focuses on whether the reduced supply temperature guarantees the comfort in the building, considering the coldest room with a heating setpoint of 22 °C and a minimum acceptable indoor temperature of 19,0 °C.

The simulated buildings are based on the data available from the IEE project Tabula. Generic models representative for Norwegian apartment blocks have been developed in IDA ICE. They consist of eight age classes and three levels of energy performance: • Prior to 1956, from 1956-1970, 1971-1980, 1981-1990, 1991-2000, 2001-2010, 2011-2020 and 2020 →. • Original, intermediate renovation and standard renovation For the intermediate renovation level, it is only the windows and infiltration rates that have been changed. Tabula also includes an ambitious renovation, but this has not been modelled as the results are expected to be similar to those for the newest age class. Simulations are performed with two different dimensioning temperature levels for the radiators typical for Norwegian buildings; 80/60 and 60/40 °C. The results showed that it is possible to reduce the supply temperature to the radiators from 80 to 60 °C for buildings from 1971-80 and all newer age classes, even for the non-renovated buildings. This is based on a minimum acceptable indoor temperature of 19.0 °C (according to the Norwegian building regulations, TEK). For the older age classes, an acceptable indoor temperature is not achieved for the non-renovated buildings when reducing the supply temperature. Although it is sufficient to perform the intermediate renovation to maintain temperatures above 19 °C, it is highly recommended to perform the standard renovation for these age classes to reduce the number of hours with a significantly reduced indoor temperature compared to the setpoint temperature. In addition to reduce the heating demand and thus lead to energy savings, this will also ensure that the occupants are satisfied with their thermal environment. It is important to note that the conclusions would be different if the minimum acceptable temperature was set higher, for instance at 20 or 21 °C. The results can be used by district heating companies, building owners, contractors and consulting companies in order to evaluate the introduction of 4th generation district heating in Norwegian apartment blocks. Both the models and excel sheets with hourly results are available for partners and researchers within FME ZEN.

ZEN Report 9,


eTransport is a linear optimization tool for evaluating energy supply alternatives for building areas. This report describes an improved, more realistic district heating (DH) module that has been developed for eTransport. The new module includes several improvements as compared to the previous module:

  • Varying mass flow that depends on the heat load, as opposed to constant mass flow. 
  • Pressure included as a variable, with certain limits for minimum pressure and minimum pressure drop at the loads. 
  • Calculation of pumping power is included in the module, and pumping power due to pressure losses in pipes and at loads is included in the objective function 
  • A more realistic calculation of heat losses included, and the heat losses are included in the heat load 
  • The module allows supply flow to both directions in a pipe; a property which is relevant when more heat sources are present in a DH grid. This feature is however yet to be tested properly.

The report presents the main equations required for mathematical description of a district heating system are presented, followed by the approach taken for linear representation of these equations, required for eTransport. The report includes a brief evaluation of the module using a simple test network, and discusses the simplifications and limitations of the present module, giving suggestions for further improvements.


Fjernvarme er en viktig muliggjørende teknologi i det grønne skiftet. Fjernvarme kan nyttiggjøre energi som ellers ville gått til spille, slik som gjenvunnet varme fra avfallsforbrenning og industriprosesser; eller mindre spillvarmekilder tilgjengelig i byer, slik som datasentre og store matvarebutikker. Ved hjelp av et fjernvarmesystem kan slike kilder anvendes til oppvarming av boliger og næringsbygg. Med et godt samspill med kraftnettet bidrar fjernvarme i tettbygde strøk til å avlaste kraftnettet og tilgjengeliggjøring elektrisitet til andre formål enn til oppvarming. Bygging av et fjernvarmesystem krever store investeringer i startfasen, og dermed er det viktig å vite hvilke energikilder man bør velge til et gitt område for å minimere tilbakebetalingstiden. Det er derfor vanlig å bruke planleggingsverktøy for sammenlikning av ulike energiforsyningsalternativer til området. eTransport er et slikt verktøy, lagd av SINTEF Energi i 2006. Verktøyet skal oppgraderes og videreutvikles i FME ZEN. eTransport omfatter flere energibærere, og finner den optimale måten til å drifte energisystemet, samt en optimal ekspansjonsplan i et geografisk definert område. I mange tilfeller vil det være konkurransen mellom ulike energibærere: behovet for oppvarming kan dekkes av elektrisitet eller av et fjernvarmesystem og varme kan genereres fra kilder. eTransport beregner de årlige driftskostnadene for ulike energisystemdesign, og sender disse til en investeringsmodell som finner en optimal ekspansjonsplan.

Denne rapporten beskriver en oppgradering av fjernvarmemodulen i eTransport. I den tidligere versjonen av eTransport var modulen for beskrivelse av et fjernvarmesystem svært forenklet. Den oppgraderte modulen er mer realistisk i forhold til beregning av massestrøm, varmetap, trykktap og pumpearbeid. Modulen tillater dessuten forsyning av varme i begge retninger i et rør, noe som kan være aktuelt i et varmenett som utnytter flere, distribuerte varmekilder. eTransport et lineært optimalisverktøy, og rapporten presenterer den valgte tilnærmingen for lineær formulering av de viktigste likningene for beskrivelse av et fjernvarmesystem.

Conference proceedings,
2018 International Conference on Information and Communication Technology Convergence (ICTC) ,


A huge volume of data are being generated from multiple sources, including smart cities, the IoT devices, scientific modeling, or different big data simulations; but also from users’ daily activities. These daily new data are added to historical repositories, providing the huge and complex universe of the digital data. Recently, the Fog-to-Cloud (F2C) data management architecture is envisioned to handle all big data complexities, from IoT devices (the closest layer to the users) to cloud technologies (the farthest layer to the IoT devices), as well as different data phases from creation to usage from fog to cloud scenario. Moreover, the F2C data management architecture can have several benefits from the combined advantages of fog (distributed) and cloud (centralized) technologies including reducing network traffic, reducing latencies drastically while improving security.
In this paper, we have several novel contributions. First, we described the previous studies of the Zero Emission Buildings (ZEB) in the context of the data flow and movement architecture. Second, we have proposed Zero Emission Neighbourhoods (ZEN) data management architecture for smart city scenarios based on a distributed hierarchical F2C data management. Indeed, we used the 6Vs big data challenges (Volume, Variety, Velocity, Variability, Veracity, and Value) for evaluating the data management architectures (including ZEB and ZEN). The result of the evaluation shows that our proposed ZEN data management architecture can address 6Vs challenges and is able to manage the data lifecycle from its production up to its usage.

Tereshchenko, T. & Nord, N. (2018) Future Trends in District Heating Development
Current Sustainable/Renewable Energy Reports,
volume 5 ,

Purpose of Review

This article describes challenges that should be overcome towards implementation of low-temperature district heating (LTDH). The trends in development, operational issues, and legislative framework were revised.

Recent Findings

The new substation design with solutions to avoid legionella bacteria issue, improved network topology and control strategies, opportunities of LTDH for buildings under various renovation stages and construction year were identified as the most crucial for the transition to 4th generation district heating (DH). Importance of heat load aggregation to avoid peak load issue in the areas with low-energy buildings (LEB) and solutions for transition from high temperature to low temperatures in the DH network have been shown


The findings indicate that there is a huge potential for achieving low-carbon society and improvement in energy efficiency under transition to LTDH. The solutions for transition from high-temperature DH to LTDH exist; however, they need good policies and market availability to be implemented.

volume 10,
pages 1-19,


The building industry is responsible for approximately 40% of energy consumption and 36% of greenhouse gas emissions in the European Union (EU). The most efficient way of reducing a building’s environmental impact is addressing it in the design stage. Here, design freedom is the greatest, but uncertainty is high and there is a nearly limitless number of design options.

Based on experiences with zero emission buildings (ZEB) and zero emission neighbourhoods (ZEN), a mapping review has been conducted to analyse how parametric life cycle assessment (LCA) and algorithms have been used to address neighbourhoods, buildings, and construction materials. Results have identified a general gap of knowledge regarding the use of parametric LCA models for decision-support purposes, demonstrated by the substantial focus on analytical methods compared to procedural methods. Implications for the evolution from ZEB to ZEN are twofold: (i) an integrated approach with multiple tools and methods is required, and (ii) further development of algorithms in the tool are needed to address complexity, sensitivity, and uncertainty.

This study is expected to foster the development of algorithmic approaches to improve the ZEB tool as a decision-support tool. Further research should address the key questions of when and how

Rasmussen, F.N., Malmqvist, T., Moncaster, A., Houlihan-Wiberg, A. & Birgirsdottir, H. (2018) Analysing methodological choices in calculations of embodied energy and GHG emissions from buildings
Energy and Buildings,
volume 158,
pages 1487-1498,


The importance of embodied energy and embodied greenhouse gas emissions (EEG) from buildings is gaining increased interest within building sector initiatives and on a regulatory level. In spite of recent harmonisation efforts, reported results of EEG from building case studies display large variations in numerical results due to variations in the chosen indicators, data sources and both temporal and physical boundaries.

The aim of this paper is to add value to existing EEG research knowledge by systematically explaining and analysing the methodological implications of the quantitative results obtained, thus providing a framework for reinterpretation and more effective comparison. The collection of over 80 international case studies developed within the International Energy Agency’s EBC Annex 57 research programme is used as the quantitative foundation to present a comprehensive analysis of the multiple interacting methodological parameters. The analysis of methodological parameters is structured by the stepwise methodological choices made in the building EEG assessment practice. Each of six assessment process steps involves one or more methodological choices relevant to the EEG results, and the combination potentials between these many parameters signifies a multitude of ways in which the outcome of EEG studies are affected.

Nord, N. (2018) Testet kapillærrørsystem i ZEB Test Cell
Norsk VVS,
volume 6,
pages 18-20,

Malmqvist, T., Nehasilova, M., Moncaster, A., Birgisdottir, H., Rasmussen, F.N, Houlihan-Wiberg, A. & Potting, (2018) Design and construction strategies for reducing embodied impacts from buildings – Case study analysis
Energy and Buildings,
volume 166,
pages 35-47,


The dominance of operational energy and related greenhouse gas (GHG) emissions of most existing buildings is decreasing in new construction, when primary fossil energy of building operation decreases as result of the implementation of energy efficiency measures as well as a decarbonisation of national energy mixes. Stakeholders therefore have a growing interest in understanding the possibilities for reducing embodied impacts in buildings. In the IEA EBC project ‘Annex 57’ a broad call for case studies was launched with the aim to identify design strategies for reducing embodied energy and GHG emissions (EEG) from buildings.

The aim of this paper is to identify and provide a collected and comprehensive overview of quantitative reduction potentials of the particular EEG reduction strategies which should be considered by the stakeholders engaged in, and with the capacity to influence the outcome of, individual building projects. This is done by a systematic analysis of the Annex 57 case study collection as well as additional scientific literature. While it should be noted that the actual EEG savings at building level illustrated in this collection of studies are only applicable to each specific case, importantly this multiple cross-case analysis has provided rigorous evidence of the considerable potential to reduce embodied impacts in the design and construction of new and refurbished buildings.

Energy Research & Social Science,
volume 39,
pages 226-233 ,


The Trondheim Living Lab is a detached single-family zero emission building (ZEB) that is planned to reach a zero-emission balance over the course of its estimated 60-year lifetime. This is achieved by a broad variety of technical strategies such as passive and active energy design and efficient installations, as well as calculations of embodied emissions. In qualitative experiments conducted between September 2015 and April 2016 six different groups lived in the house for 25 days each. Based on direct observation (mainly through sensors registering temperature, humidity, CO2 levels and energy use), participant observation and interviews before, during and after the stay, the paper analyses the unfolding domestication of the building along three dimensions; practical, symbolic and cognitive.

The paper provides an account of which expected or unexpected occupant actions matter in which way for the zero emission ambitions of the building. Moreover, by studying the way in which the six groups within the three different categories student, family and elderly experienced living in this demonstration building this paper contributes a more detailed understanding of the overall acceptance of a ZEB in Norway.

Kristjansdottir, T.F., Houlihan-Wiberg, A., Andresen, I., Georges, L., Heeren, N., Good, C.S. & Brattebø, H. (2018) Is a net life cycle balance for energy and materials achievable for a zero emission single-family building in Norway?
Energy and Buildings,
volume 168,
pages 457-469 ,


In this study, the objective is to redesign a previous concept for a single-family Zero greenhouse gas Emission Building (ZEB). The concept is redesigned based on comparing greenhouse gas (GHG) emission loads and compensation from different design solutions applied in Norwegian single-family ZEB pilot buildings and selected sensitivity studies. The objective is to see if a previously developed ZEB model (2011) can be redesigned to achieve a life cycle energy and material emission balance (ZEB-OM), which previously was not achieved.

Five different design parameters are evaluated: area efficiency, embodied emissions in the envelope, insulation thickness, heating systems and different roof forms with respect to the photovoltaic area. Embodied emissions reductions were possible in the ground foundation, from around 1 kg CO2/m2 to 0.6 kg CO2/m2 per year. Both models are able to compensate for all operational emissions. The new model is in addition able to compensate for 60% of embodied emissions, whereas the previous model only could compensate for 5%. The new model does not reach the life cycle energy and material balance. The paper presents and discusses different approaches for achieving the ZEB-OM balance. Further concept model optimization is needed.

Junker, R.G., Azar, A.G., Lopes, R., Lindberg, K.B., Reynders, G., Relan, R. & Madsen, H. (2018) Characterizing the energy flexibility of buildings and districts
Applied Energy,
volume 225,
pages 175-182,


The large penetration rate of renewable energy sources leads to challenges in planning and controlling the energy production, transmission, and distribution in power systems. A potential solution is found in a paradigm shift from traditional supply control to demand control. To address such changes, a first step lays in a formal and robust characterization of the energy flexibility on the demand side. The most common way to characterize the energy flexibility is by considering it as a static function at every time instant. The validity of this approach is questionable because energy-based systems are never at steady-state. Therefore, in this paper, a novel methodology to characterize the energy flexibility as a dynamic function is proposed, which is titled as the Flexibility Function.

The Flexibility Function brings new possibilities for enabling the grid operators or other operators to control the demand through the use of penalty signals (e.g., price, CO2, etc.). For instance, CO2-based controllers can be used to accelerate the transition to a fossil-free society. Contrary to previous static approaches to quantify Energy Flexibility, the dynamic nature of the Flexibility Function enables a Flexibility Index, which describes to which extent a building is able to respond to the grid’s need for flexibility. In order to validate the proposed methodologies, a case study is presented, demonstrating how different Flexibility Functions enable the utilization of the flexibility in different types of buildings, which are integrated with renewable energies.

Dziedzic, J.W., Yan, D. & Novakovic, V. (2019) Real Time Measurement of Dynamic Metabolic Factor (D-MET)
Conference proceedings,
Cold Climate HVAC 2018 ,


The presented study describes developing a method for observing building occupants’ activity. Once their activity is registered, such data can be used to identify typical patterns in their behaviour. The collected information will support development of an occupant-behaviour-energy-related model in residential buildings. Data registration was done with the use of the Microsoft Kinect device as a depth registration camera. This research explores an innovative approach to investigating residents’ living and working habits. It supports the already existing thermal comfort models by delivering high resolution information about occupants’ activities. The obtained solution and its output will be used in the next stage of developing a dynamic metabolic rate (D-MET) model that will simulate the MET value. With proper data, it will be possible to estimate the real impact of occupants and their behaviour on energy consumption of buildings.

Dong, B., Kjærgaard, M.B., Simone, M.D., Gunay, H.B., O'Brien, W., Dafni, M., Dziedzic, J. & Zhao, J. (2018) Sensing and Data Acquisition
Conference proceedings,
Exploring Occupant Behavior in Buildings,
chapter 4,
pages 77-105,


Occupant sensing and data acquisition are essential elements for occupant behavior research. A wide range of different types of sensors has been implemented to collect rich information on occupants and their interactions with the built environment, such as presence, actions, power consumption, etc. This information establishes a foundation to study the physiological, psychological, and social aspects of occupant behavior. This chapter summarizes existing occupancy and occupant behavior sensing and data acquisition technologies in terms of field applications, and develops nine performance metrics for their evaluation. The reviewed technologies focus on both occupants’ presence and interactions with the built environment, and are grouped into six major categories: image-based, threshold and mechanical, motion sensing, radio-based, human-in-the-loop, and consumption sensing. This chapter provides an overview and discussion of different current state-of-the-art and future sensing technologies for researchers.

Backe, S., Crespo del Granado, P., Pinel, D., Korpås, M., Tomasgard, A. & Lindberg, K.B. (2018) Towards Zero Emission Neighbourhoods: Implications for the Power System
Conference proceedings,
2018 15th International Conference on the European Energy Market - EEM ,


This paper investigates the development of neighbourhoods with ambitious emission targets in the Nordic countries and their value for the power system. The targets relate to compensating for emissions in neighbourhoods through local low-carbon electricity and heat production. The first part of our analysis investigates local generation expansion with a neighbourhood perspective using a mixed integer linear programming model. The second part investigates the value of representative neighbourhoods with a country perspective using a generation and transmission capacity expansion model. When coupling the models, results indicate that neighbourhoods with co-generation of electricity and heat are most attractive for the power system in the Nordics, while neighbourhoods with solar PV provide most emission reduction.

M. K. Wiik, S. M. Fufa, J. Krogstie, D. Ahlers, A. Wyckmans, P. Driscoll, H. Brattebø, A. Gustavsen (2018) Zero emission neighbourhoods in smart cities: Definition, key performance indicators and assessment criteria: version 1.0. Bilingual version.
ZEN Report 7,

This document outlines the definition, key performance indicators (KPI) and assessment criteria for the Research Centre on Zero Emission Neighbourhoods in Smart Cities (ZEN research centre). This first version of the ZEN definition includes contributions from the ZEN partners. In total, around 50 people involved in the ZEN research centre have contributed to this document.


Denne rapporten beskriver definisjonen, nøkkelindikatorer og vurderingskriterier som benyttes i forskningssenteret for nullutslippsområde i smarte byer (ZEN senteret). Dette er den første utgaven og inkluderer innspill og bidrag fra ZEN partnerne. Til sammen har omkring femti eksperter fra ZEN senteret bidratt til dette dokumentet. Rapporten foreligger både på engelsk og norsk.

M. K. Wiik, S. M. Fufa, J. Krogstie, D. Ahlers, A. Wyckmans, P. Driscoll, H. Brattebø, A. Gustavsen

Kolstad, M.L., Backe, S., Wolfgang, O. & Sartori, I. (2018) Software tools for local energy system operation and expansion
ZEN Report 6,


This report describes existing software tools for analysing operation and expansion of local energy systems and is written in WP5 in the Research Centre on Zero Emission Neighbourhoods in Smart Cities (ZEN). WP5 in FME ZEN aims to develop and apply methodologies that identify the socioeconomic optimal operation and expansion of energy systems within demarked areas. The eTransport model is planned to be further developed and used to analyse pilot cases in ZEN. This report provides a brief description of the eTransport model and other alternative models found in the literature or used by partners in FME ZEN. The models are assessed based on their suitability to address the planned research tasks in FEM ZEN WP5. The report also includes a description of models developed for global and international analysis.

We are grateful for views and suggestions provided by Henrik Madsen (professor at DTU), and for comments provided by Anne Grete Hestnes (professor NTNU)

M. L. Kolstad, S. Backe, O. Wolfgang, I. Sartori

Justo-Alonso, M. (2018) Er det nok å åpne vinduet?
further featured in no. of sources: 2,

Ett spørsmål klarer ikke arkitekter og ingeniører å bli enige om. Er det best å bare åpne vinduene om du vil lufte ut en bygning?

Maria Justo Alonso

ZEN Memo 5,

Dette dokumentet inneholder forslag til kriterier for hva som skal være krav og retningslinjer, samt roller og ansvar knyttet til å være et pilotprosjekt i forskingssenteret Zero Emission Neighbourhoods.

Inger Andresen

ZEN Memo 4,

Dette dokumentet inneholder forslag til kriterier for hva som skal være krav og retningslinjer, samt roller og ansvar knyttet til å være et CASE-prosjekt i forskingssenteret Zero Emission Neighbourhoods.

Inger Andresen

Sørensen, Å.L., Fredriksen, E., Walnum, H.T., Skeie, K.S. & Andresen, I. (2018) ZEN pilot survey – Initial plans for thermal and electrical use, generation, distribution and storage
ZEN Memo 3,

To develop zero emission neighbourhoods in smart cities, knowledge is needed in a number of areas. This pilot survey describes the initial plans for the ZEN pilot areas regarding thermal and electrical use, generation, distribution and storage.

Åse Lekang Sørensen, Eyvind Fredriksen, Harald Taxt Walnum, Kristian Stenerud Skeie, Inger Andresen

Sørensen, Å.L., Jiang, S., Torsæter, B.N. & Völler, S. (2018) Smart EV charging systems for zero emission neighbourhoods
ZEN Report 5,


The increased use of electric vehicles (EVs) calls for new and innovative solutions for charging infrastructure. At the same time, it is desirable to improve the energy flexibility of neighbourhoods. This paper presents state-of-the-art for smart EV charging systems, with focus on Norway.

The aim of the study is to start investigating how smart EV charging systems can improve the energy flexibility in a Zero Emission Neighbourhood (ZEN). The intention is that the study will be useful when evaluating activities and technologies for the ZEN pilot areas.

The paper presents energy demand for EV charging and typical charging profiles. Further, it describes how charging stations can interact also with the energy need in buildings and neighbourhoods, local energy production and local electric and thermal energy storage. Examples of commercial smart EV charging systems are described.

The report lists some opportunities for testing smart EV charging in the ZEN pilot areas. Piloting of new technologies and solutions can provide more knowledge about smart EV charging systems, and how they can participate in matching energy loads in buildings and infrastructure with local electricity generation and energy storage.

Åse Lekang Sørensen, Shanshan Jiang, Bendik Nybakk Torsæter, Steve Völler

Wolfgang, O., Petersen, I., Kolstad, M.L. & Kvalsvik, K.H. (2018) Recommendations for further developments in eTransport
ZEN Memo 1,

This memo summarizes promising possibilities for the further development of eTransport, of which some are included in the ZEN work plan 2018-2019. Among other things, the described developments deal with technologies within the energy supply chains for electricity and heat, with the representation of end-users, and with the representation of fluctuations in the availability of local energy sources.

O. Wolfgang, I. Petersen, M. Lorentzen Kolstad, K. Husevåg Kvalsvik

ZEN Report 4,


This report is a part of Work Package 3 Responsive and Energy Efficient buildings. The goal for WP 3 is to create cost effective, responsive, resource and energy efficient buildings by developing low carbon technologies and construction systems based on lifecycle design strategies.

As conventional HVAC systems can only make most users satisfied with their thermal environment, there has recently been a lot of research into personal climatization systems. The aim of this literature study was to investigate whether personal heating and cooling solutions could contribute to make all users satisfied with their thermal environment. Potential energy savings are considered a bonus, but was also included in the evaluation of the literature on the subject.

Almost all of the articles reviewed in this report found that the personal climatization devices significantly improved thermal sensation and thermal comfort for the users. For both heating and cooling it was found that combining personal comfort devices resulted in higher comfort improvement and higher energy saving potential. The devices also made it possible to achieve thermal comfort outside the traditional heating and cooling setpoints, thus making it possible to extend the thermal dead-band of buildings, which could lead to substantial energy savings. There are however still some aspects of personal climatization systems where there is suggested further research, and these personal climatization systems are still not commercially available.

Øystein Rønneseth

Walnum, H.T. & Fredriksen, E. (2018) Thermal energy systems in ZEN
ZEN Report 3,

This report reviews the state-of-the-art on thermal energy systems for neighbourhoods. Its main focus is on technologies related to 4th generation district heating (4GDH), biomass combined heat and power (CHP) systems, ground source heat pumps (GSHP) and seasonal heat storage.

Harald Taxt Walnum, Eyvind Fredriksen

Næss, J.S., Sandberg, N.H., Nord, N., Vestrum, M.I., Lausselet, C., Woszczek, A., Rønneseth, Ø. & Brattebø, H. (2018) Neighbourhood building stock model for long-term dynamic analyses of energy demand and GHG emissions
ZEN Report 2,

How should sustainable neighbourhoods be designed to reduce greenhouse gas emissions towards zero? What kind of information do decision makers need to make solid future plans on the neighbourhood level? A dynamic building stock model has been developed for energy- and GHG-emission scenario analyses of neighbourhoods. The model is generic and flexible and can be used to model any neighbourhood where building stock data is available.

Jan Sandstad Næss, Nina Holck Sandberg, Natasa Nord, Magnus Inderberg Vestrum, Carine Lausselet, Aleksandra Woszczek, Øystein Rønneseth, Helge Brattebø

ZEN Report 1,

This report presents a plan for the European power market studies to be carried out within the ZEN Research Centre.

Local energy solutions such as the utilization of local renewable energy resources, and increased energy efficiency, are important for being able to reduce European greenhouse gas emissions to amounts that are in line e.g. with a 2 degree global warming. In the long run, emission levels are affected by many factors including energy system operations, investment decisions, policy instruments, social acceptance for environmental policy, amongst others. Thus, it is not trivial to calculate the full impacts of e.g. 1 TWh extra renewable energy produced locally. Still, it is possible to elaborate on and reveal important mechanisms, which will increase our understanding of those. This report present a plan for European power market studies to be carried out within the FME ZEN. The overall intention with the planned studies is not to provide more accurate numerical calculations than in previous studies, but rather to show how numerical results are affected by which economic mechanisms that are included in such studies. Thus, the studies shall be a basis for creating increased mutual understanding of arguments within FME ZEN.

Ove Wolfgang

ZEB Report 41,

This report presents a set of guidelines to assist building designers in a methodological approach to the analysis of energy systems in the early design phase of zero emission buildings. The guidelines are meant to accompany the use of a ZEB supporting tool, guiding through the necessary steps to evaluate the performance and adapt the dimensioning of different systems to the case at hand.

Igor Sartori, Sjur V. Løtveit, Kristian S. Skeie

Sartori, I., Skeie, K.S., Sørnes, K. & Andresen, I. (2018) Zero Village Bergen: Energy system analysis
ZEB Report 40,

Based on discussions with the ZEB partners, three possible solutions have been investigated for the energy system of Zero Village Bergen:

  1. District Heating (DH)
  2. Biomass fired Combined Heat and Power (Bio CHP)
  3. Ground Source Heat Pump (GSHP)
Igor Sartori, Kristian S. Skeie, Kari Sørnes, Inger Andresen

Nord, N., Tereshchenko, T., Qvistgaard, L.H., & Tryggestad, I.S. (2018) Influence of occupant behavior and operation on performance of a residential Zero Emission Building in Norway
Energy and Buildings,
volume 159,
pages 75-88,


It has been proven that occupant behavior may significantly change building energy performance. The effect of the occupant behavior is becoming even bigger when it comes to highly energy efficient buildings. Specifically Zero Emission Buildings (ZEB) may become an issue for the electric grid, because they are supposed to be actively connected to the electricity grid for electricity import and export. Therefore, the aim of this study was to evaluate the change in the energy performance of a ZEB located in Norway.

Occupant behavior was modelled by using the following methods standard schedules, well-defined profiles based on thorough statistical analysis, and stochastic methods To analyze the grid stress, 31 scenarios for different occupant behaviors were analyzed. The overall estimation of investigated parameters showed that the change in occupant behavior resulted in grid stress variance from −5% to +13% compared to the reference case based on the standard values.

The results showed that the occupant behavior might change the annual energy balance reliability by 20%. However, the results showed that the influence of the occupant behavior related to the window opening and domestic hot tap water would not significantly change the ZEB energy performance. Window opening would even decrease the cooling load. A very important conclusion of this study is that consideration of occupant behavior through challenging the standard values are highly necessary for reliable energy analysis of the ZEB solutions.

Energy and Buildings,
volume 146,
pages 220-232,


The housing sector is important for future energy savings and greenhouse gas emission mitigation. A dynamic, stock-driven and segmented dwelling stock model is applied for dwelling stock energy analyses. Renovation activity is estimated as the need for renovation during the ageing process of the stock, in contrast to exogenously defined and often unrealistic renovation rates applied in other models.

The case study of Norway 2016–2050 shows that despite stock growth, the total theoretical estimated delivered energy is expected to decrease from 2016 to 2050 by 23% (baseline) and 52% (most optimistic scenario). A large share of the energy-efficiency potential of the stock is already realized through standard renovation. The potential for further reductions through more advanced and/or more frequent renovation, compared to current practice, is surprisingly limited. However, extensive use of heat pumps and photovoltaics will give large additional future energy savings. Finally, user behaviour is highly important. A strong future rebound effect is expected as the dwelling stock becomes more energy efficient. The estimated total ‘real’ energy demand is expected to decrease by only 1% (baseline) and 36% (most optimistic scenario). Hence, reaching significant future energy and emission reductions in the Norwegian dwelling stock system will be challenging.

Seljom, P., Lindberg, K.B., Tomasgard, A., Doorman, G. & Sartori, I. (2017) The impact of Zero Energy Buildings on the Scandinavian energy system
volume 118,
pages 284-296,


This paper investigates how an extensive implementation of net Zero Energy Buildings (ZEBs) affects cost-optimal investments in the Scandinavian energy system towards 2050. Analyses are done by a stochastic TIMES model with an explicit representation of the short-term uncertainty related to electricity supply and heat demand in buildings. We define a nearly ZEB to be a highly efficient building with on-site PV production. To evaluate the flexibility requirement of the surrounding energy system, we consider no use of energy storage within the ZEBs.

The results show that ZEBs reduce the investments in non-flexible hydropower, wind power and Combined Heat and Power, and increase the use of direct electric heating and electric boilers. With building integrated PV production of 53 TWh in 2050, ZEBs increase the Scandinavian electricity generation by 16 TWh and increase the net electricity export by 19 TWh. Although the increased production reduces the electricity prices, the low heat demand in ZEBs gives a drop in the electricity consumption by 4 TWh in 2050. Finally, the results demonstrate that the Scandinavian energy system is capable of integrating a large amount of ZEBs with intermittent PV production due to the flexible hydropower in Norway and Sweden.

Sørnes, K., Fredriksen, E., Tunheim, K. & Sartori, I. (2017) Analysis of the impact resolution has on load matching in the Norwegian context
Energy Procedia,
volume 132,
pages 610-615,


Generation of energy at building level has an increasing interest in Norway, as in rest of Europe. Load matching is the correlation between the buildings generation and load, which in most cases aims at optimization of the amount of self-consumption. When analysing generation in relation to load, it is of interest to study the choice of resolution and what impact this has on load match indicators. This study analyses the importance of choosing the right resolution, starting with hourly measurements, and going down towards one-minute resolution.

Monitoring resolution has a significant impact on both the type of monitoring equipment and the data storage capacity needed. If the impact of lower resolution is small, less complex monitoring systems can be installed in projects that are not sensible to the uncertainty caused by the lack of minute-based data.
Norwegian case studies with solar power production gives data to the analysis, studying a nursing home in Oslo called Økern Sykehjem. The nursing home has been a pilot building in the European Fp7 research project ZenN, Nearly Zero Energy Neighbourhood (2012-2017), which led to the installation of 130 kW solar power panels while going through a large renovation process. Generation and load have been monitored with high-resolution since 2015 and this gives useful insight into the effect of high-resolution data monitoring compared to hourly-resolution monitoring.

Resulting graphs shows that by collecting data on a daily basis will give a wrong impression on self-consumption and self-generation by about 20% compared to hourly based data. The difference between minute based and hourly based resolution is relatively small (6%).

Zhang, L., Gustavsen, A., Jelle, B.P., Yang, L., Gao, T. & Wang, Y. (2017) Thermal conductivity of cement stabilized earth blocks
Construction and Building Materials,
volume 151,
pages 504-511,


The present study examines the effect of bulk density and cement content on the thermal conductivity of cement stabilized earth blocks (CSEB). The experimental results show that the thermal conductivity increases as a function of bulk density; changes in cement content result in a small variation in thermal conductivity of CSEB at a given bulk density. No obvious linear relationship between the thermal conductivity and cement content of CSEB has been observed. However, a significant increase of compressive strength of CSEB caused by the addition of cement has been observed; moreover, the compressive strength of CSEB increases with increasing cement content. CSEB show potential in earth buildings due to their improved compressive strength and reduced thermal conductivity.