Analysing methodological choices in calculations of embodied energy and GHG emissions from buildings


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.

Design and construction strategies for reducing embodied impacts from buildings – Case study analysis


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.

Domestication, acceptance and zero emission ambitions: Insights from a mixed method, experimental research design in a Norwegian Living Lab


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.

Is a net life cycle balance for energy and materials achievable for a zero emission single-family building in Norway?


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.

Characterizing the energy flexibility of buildings and districts


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.

Real Time Measurement of Dynamic Metabolic Factor (D-MET)


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.

Sensing and Data Acquisition


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.

Towards Zero Emission Neighbourhoods: Implications for the Power System


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.

Zero emission neighbourhoods in smart cities: Definition, key performance indicators and assessment criteria: version 1.0. Bilingual version.

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