Zero Emission Buildings

practitioners looking for ways to contribute to a sustainable future.

A.G. HESTNES AND N.L. EIK-NES (EDS.)

The book describes some of the key knowledge areas needed when designing, building, and operating zero emission buildings. It should be read by students of architecture and engineering as well as

ZERO EMISSION BUILDINGS

This book shows what can be achieved when researchers and practitioners work together to develop the building performance level of tomorrow, but needed today. The book is based on the research and development activities performed in the Research Centre on Zero Emission Buildings (the ZEB Centre, www.zeb.no) from 2009 to 2017.

Emissions of CO2 and other greenhouse gases must be reduced to limit global warming. Thus, the goal of the ZEB Centre has been to develop knowledge, competitive products, and solutions for existing and new buildings whose production, operation, and demolition give zero emissions of greenhouse gases while also considering the users’ needs for comfort and flexibility. The results presented here are based on research as well as experience from the development of nine real demonstration buildings.

ZERO EMISSION BUILDINGS

ISBN 978-82-450-2055-7

Omslag med klaffer NY 08_12.indd 1

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ZERO EMISSION BUILDINGS

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ANNE GRETE HESTNES AND NANCY LEA EIK-NES (EDS)

ZERO EMISSION BUILDINGS

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Copyright © 2017 by Vigmostad & Bjørke AS All Rights Reserved ISBN: 978-82-450-2055-7 Graphic production: John Grieg, Bergen Cover design by Snøhetta

Inquiries about this text can be directed to: Fagbokforlaget Kanalveien 51 5068 Bergen Tel.: 55 38 88 00 Fax: 55 38 88 01 e-mail: fagbokforlaget@fagbokforlaget.no www.fagbokforlaget.no All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photo-copying, recording, or otherwise, without the prior written permission of the publisher.

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FOREWORD Zero emission buildings (ZEBs) will be an important and necessary component in a more environment-friendly society. Developing zero emission buildings requires new knowledge in a large number of fields and will result in a variety of solutions, depending on the context, the local climate, and the specific needs of the potential users.

For the last eight years, the Research Centre on Zero Emission Buildings has been developing and testing different tools, technologies, and solutions for such buildings, and some of the results obtained and the knowledge gained are described in this book (all publications can be found on www.zeb.no). It is not a book that will cover all that needs to be known about low energy- and low emission buildings. For that, standard textbooks on energy efficiency in buildings are a useful supplement. This book assumes that the basics are known. It does, however, cover many of the critical aspects that need to be addressed to reach the goal of zero emissions over the lifetime of a building. Its main goal is to provide the reader with some of the additional knowledge the ZEB Centre has developed over the last eight years.

Not only designing such buildings, but building them, operating them and, not least, ensuring that clients and users will want such buildings, requires the active involvement of a wide range of professionals. Researchers from fields as diverse as physics, architecture, and social science have worked in the Centre, and the results of work in all relevant fields are included in this book. It is therefore written by a total of 16 authors and has been a joint effort by the researchers in the Centre and its partners in the Norwegian building industry.

The Research Centre on Zero Emission Buildings (ZEB) was hosted by the Norwegian University of Science and Technology (NTNU) and jointly managed by NTNU and SINTEF. ZEB gratefully acknowledges the support from the Research Council of Norway, BNL – Federation of construction industries, Brødrene Dahl, ByBo, Caverion Norge AS, DiBK – Norwegian Building Authority, DuPont, Enova SF, Entra, Forsvarsbygg, Glava, Husbanken, Sør-Trøndelag fylkeskommune, Isola, Multiconsult, NorDan, Norsk Teknologi, Protan, Sapa, Skanska, Snøhetta, Statsbygg, VELUX, and Weber.

Anne Grete Hestnes 5

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CONTENTS PART I | INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 ANNE GRETE HESTNES, NTNU / ARILD GUSTAVSEN, NTNU

The ZEB Centre definition of zero emission buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Zero emission buildings as part of the larger energy system . . . . . . . . . . . . . . . . . . . . . . . . . . 19 The research activities in the ZEB Centre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

PART II | THE ANSWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 CHAPTER 2 .1

THE ZEB PILOT BUILDINGS: STRATEGIES USED . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 INGER ANDRESEN, NTNU

The design and construction processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 CHAPTER 2 .2

THE INTEGRATED DESIGN PROCESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 INGER ANDRESEN, NTNU / TINE HEGLI, SNØHETTA

Trias energetica – reduce first . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Integrate parts into a whole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 The main steps in the IED Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 7

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BEHIND THE SCENES: DESIGNING POWERHOUSE KJØRBO . . . . . . . . . . . . . . . . . . . 48 TINE HEGLI, SNØHETTA

Powerhouse Kjørbo, schematic design, autumn 2012. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 The new complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Key turning points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Results and findings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 CHAPTER 2 .3

IS THERE A ZEB ARCHITECTURE? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 ANNE GUNNARSHAUG LIEN, SINTEF

Solar energy and the building form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Compact building volume or large surfaces for solar energy harvesting . . . . . . . . . . . . . . . . 55 Ventilation and cooling strategies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Flexibility and the organization of layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Daylight, view, and aesthetic qualities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Reduced embodied emissions influence the choice of materials. . . . . . . . . . . . . . . . . . . . . . . 59 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 CHAPTER 2 .4

DAYLIGHT! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 BARBARA SZYBINSKA MATUSIAK, NTNU

Health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Aesthetic experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 CHAPTER 2 .5

LOW CARBON SOLUTIONS: THE KEY DRIVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 TORHILDUR FJOLA KRISTJANSDOTTIR, NTNU

The main emission concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Life cycle emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

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The emissions balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 The relative importance of embodied emissions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Common calculation procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Examples of embodied emissions calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 CHAPTER 2 .6

THE RIGHT MATERIALS: MORE IMPORTANT THAN EVER . . . . . . . . . . . . . . . . . . . . . 81 BJØRN PETTER JELLE, NTNU/SINTEF / TAO GAO, NTNU / MARIANNE KJENDSETH WIIK, SINTEF / REIDUN DAHL SCHLANBUSCH, SINTEF

Life cycle GHG emissions of building materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 New materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 CHAPTER 2 .7

THE BUILDING ENVELOPE: IT IS NOT ONLY ABOUT INSULATION . . . . . . . . . . . . . . . 95 BIRGIT RISHOLT, SINTEF

Optimal thermal insulation of the building envelope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Retrofitting of existing buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Future prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 CHAPTER 2 .8

HEATING AND COOLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 LAURENT GEORGES, NTNU

Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Space cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 User behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

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CHAPTER 2 .9

VENTILATION: BETTER QUALITY WITH LESS ENERGY . . . . . . . . . . . . . . . . . . . . . . 123 HANS MARTIN MATHISEN, NTNU

Air distribution in rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Energy efficient air distribution systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Required airflow rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 The importance of good indoor air quality for productivity and health . . . . . . . . . . . . . . . . 133 CHAPTER 2 .10

ENERGY GENERATION: FOCUS ON RENEWABLES . . . . . . . . . . . . . . . . . . . . . . . . . 137 VOJISLAV NOVAKOVIC, NTNU

Obtaining energy balance in zero emission buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Energy sources and technologies for onsite generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 CHAPTER 2 .11

FROM POTENTIAL TO PERFORMANCE: PEOPLE MATTER . . . . . . . . . . . . . . . . . . . . 151 THOMAS BERKER, NTNU

End-users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Building operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 Implementation of zero emission buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

PART III | THE ZEB PILOT BUILDINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 INGER ANDRESEN, NTNU

Powerhouse Kjørbo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 ZEB House Multikomfort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Visund, Haakonsvern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Skarpnes, Arendal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 ZEB Living Lab, Trondheim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Powerhouse Brattørkaia, Trondheim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207

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Heimdal VGS, Trondheim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 Campus Evenstad . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 Zero Village Bergen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 ZEB reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 PhD theses by ZEB candidates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

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PART I

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|

INTRODUCTION

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INTRODUCTION ANNE GRETE HESTNES, NTNU / ARILD GUSTAVSEN, NTNU

The reduction of energy use and greenhouse gas (GHG) emissions will be the most important measure to combat global warming – at least during the next 20 years. Reports from both the OECD and the IEA claim that in order to reach the goal of limiting the concentration of greenhouse gases in the atmosphere to 450 ppm, energy efficiency will have to be responsible for two thirds of the emissions reduction. In the western world, buildings account for approximately a third of both all energy use and of greenhouse gas emissions (IEA, 2012 and 2015). Energy reduction in the building sector is therefore crucial. At the same time it is more cost effective and environment-friendly than extending the capacity in the energy supply system (IPCC, 2007).

In Norway, the situation is the same. Buildings account for approximately one third of energy use and of greenhouse gas emissions. In addition, they account for nearly 80% of electricity use (SSB, 2011 and 2012). Much has already been done to reduce the use of electricity for heating and to replace electric space heaters with heating based on solar energy and biomass. As a result, the need for CO emissions space heating in new Norwegian buildings is minimal. What remains is basically the need for hot tap water and for electricity to run fans, pumps, lights, and appliances. For new buildings, the focus is therefore shifting to efficient equipment, to the embodied energy and emissions in materials, and to Existing TEK’10 TEK’15 TEK’20 clean energy supply. buildings Passive house Almost zero energy However, if the goal of significantly reducing emissions from the building sector

Figure 1: The development of GHG emissions in typical Norwegian buildings built according to different building codes.

Source: Inger Andresen

2

Emissions from production of materials Emissions from energy use for operation Local generation of renewable energy

TEK’25 Zero energy

www.ntnu.no

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is to be achieved, the primary focus needs to be on existing buildings rather than on new buildings. At least 50% of the buildings in 2050 have already been built, and in these buildings the demand for space heating is still significant. The renovation rate in Norway, and also internationally, is quite low. If it is to increase, renovation activities aimed at reduced space heating demand/increased energy efficiency also need to address indoor comfort and architectural quality as well as the possibility of integrating energy generating elements. This is often a difficult challenge, especially in buildings with a certain architectural and/or historic value. In these cases it is especially important to use measures that do not influence the architecture to any significant degree nor involve unnecessary replacement of original materials.

In both existing and new buildings, the total energy used for operation should be further reduced, and this requires measures related both to the building envelope and to the technical equipment/building services. Furthermore, building integrated solutions for renewable thermal and electrical energy systems should be used, and the focus on using materials that require little energy in production and that cause fewer emissions of greenhouse gases must increase significantly.

The use of building integrated renewable energy systems such as solar thermal collectors and solar cells has become increasingly important. It should not be forgotten, however, that reducing energy use (improving energy efficiency) should be the first step, as it is still true that “the most environmentally friendly kilowatt-hour is the one not used”. The energy used, and the greenhouse gases emitted, are in all cases greater for elements such as solar cells and wind turbines than for traditional building elements.

The ZEB Centre definition of zero emission buildings By 2020, all buildings in the EU are supposed to be “nearly zero energy”. Norway has followed suit and intends to enforce the same requirements. It is, however, not clear exactly what “nearly” means, so this is up to national, and sometimes individual, interpretation.

The ZEB Centre has taken a step further by skipping the word “nearly” and aiming for a net zero balance over the lifetime of a building. It has also chosen to consider greenhouse gas emissions rather than energy, as it is the greenhouse gas emissions that are the primary culprit when it comes to global warming. The ZEB Centre’s definition is very ambitious, as emissions from production of materials, construction, operation, and demolition all have to be counted in the balance.

Conceptually, a zero energy building is a building with a greatly reduced energy demand, such that this energy demand can be balanced by an equivalent generation of electricity (or other energy carriers) from renewable sources. In a zero emission building, such a balance is not achieved directly on the energy demand and generation but 16

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Demolition

Energy use CO2 Emissions

Energy generation CO2 Compensation

on the associated greenhouse gas emissions.

Materials Construction Use Figure 2 illustrates what the balance of a zero emission building may look like. The circles indicate the relative sizes of the various items in the balance. As has been seen in the buildings studied, the embodied emissions may exceed the emissions from operation. At the same time, the emissions from the production of the materials used are far more significant than the emissions from construction and/or from demolition. In the case of demolition, there may also be some energy gained, for instance by the incineration of waste, as indicated by the dashed green circle.

System boundaries:

Figure 2: Illustration of the emissions balance of a zero emission building.

Source: www.zeb.no

There is a continuous discussion of where to draw the system boundaries, i.e. what energy producing elements to include in the balance. It may be that only systems placed on the building itself (such as solar thermal collectors and solar cells) are included, or that an installation on the site, or possibly an installation somewhere else (such as a centrally placed combined heat and power plant or a large wind turbine placed on a nearby mountain top), is also accounted for. For electricity generation, the ZEB Centre has chosen to include equipment on the building site only. The argument for this is that buildings provide sufficient infrastructure for such installations and that generating installations other places should rather be used as part of the general electricity supply system. The generation of thermal energy can be either on- or offsite, but emissions from the actual energy mix must be included. In this case, system losses occurring from the generation site to the building must be taken into account.

The balance between demand and supply: Figure 3 is a graphic illustration of the balance between the energy demand for operation and the renewable energy supplied, plotting the weighted demand on the x-axis and the weighted supply on the y-axis. The balance is achieved when the weighted supply matches the demand over a period of time, usually a year. The term “net zero� is

INTRODUCTION

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Weighted supply [kWh, CO2, etc]

Net zero balance line

Net ZEB Energy supply

Reference building

Weighted demand [kWh, CO2, etc]

Energy efficiency

Figure 3: Graphic representation of the ZEB balance.

Source: Satori et al. (2012)

• •

commonly used when the calculation period is a year.

The ZEB balance can be determined either by the balance between delivered and exported energy, or between load and generation. The reference building may represent the performance of a new building built according to the minimum requirements of the national building code or the performance of an existing building prior to renovation.

Starting from such a reference case, the pathway to a net ZEB is given by the balance between two actions:

reducing energy demand (x-axis) by means of energy efficiency measures; generating electricity as well as thermal energy by means of energy supply options to get enough credits (y-axis) to achieve the balance.

In most cases, major energy efficiency measures are needed, as onsite generation options are limited, for instance by the availability of suitable surface areas for solar systems. This is especially the case in buildings with several stories.

The weighting system converts the physical units into other metrics, such as primary energy or carbon equivalent emissions, by accounting for the energy used (or emissions released) to extract, generate, and deliver energy. Weighting factors may also reflect political preferences rather than purely scientific or engineering considerations.

Levels of ambition As stated, the ZEB Centre’s definition of a zero emission building is very ambitious. It focuses on emissions rather than on energy and includes all GHG-emissions over a building’s lifetime. This means that emissions from production, operation, and demolition have to be compensated for by production of renewable energy onsite. It also means that the building should produce more renewable energy than it needs for operation. This is, however, rather challenging both technically and economically. In the development of the ZEB Centre’s pilot buildings, several ambition levels have therefore been used. These are illustrated in figure 4, where ZEB Operation minus EQuipment (ZEB-O÷EQ) represents the lowest and ZEB-COME the highest level of ambition.

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Kg CO2eq/m2

The goal is to reach the highest ambition level. As the main demand is for electricity, the solution in many cases has been to use solar cells as the energy ZEB-OM generating installation. For in(A1-A3,B4***,B6) stance, by covering the roof of the building with solar cells it ZEB-O (B6) is possible to compensate for ZEB-O EQ (B6*) the energy demand for heating, cooling, and ventilation, i.e. to End of life Construction process reach the ZEB-O-EQ ambition Embodied material emissions Energy use equipment level. It is more difficult to comEnergy use excluding equipment pensate for the operation of equipment and for the production of materials as well. In that case, the facades also need to be covered with energy generating elements and/or significantly more efficient (and costly) cells need to be used. Experiences with reaching these levels in real building projects are further described in Part III.

ZEB-COME

(A1-A5,B4,B6,C1-C4)

ZEB-COM

(A1-A5,B4***,B6)

Figure 4: The various ZEB ambition levels.

Source: Fufa et al. (2016)

Zero emission buildings as part of the larger energy system The main reason for reducing energy use and using only renewable energy is, as stated, to reduce the emissions of greenhouse gases caused by buildings. The European Commission’s Roadmap states that by 2050, the total of GHG emissions should be cut by 90% (compared to 1990 levels). An important measure in this respect is the Commission’s intention to cut emissions in the building sector by 90% by the same time. If their goals are to be achieved, large scale deployment of zero emission buildings will be crucial.

At the same time, this will support several other important goals, such as increased employment and enhanced economic activity, improved quality of life, and a lower dependence on fossil fuels.

Emissions related to energy supply The EU goals also require that emissions from the energy generation system be reduced by 90%. This means that in time, the materials and components may be produced using almost emission-free energy and that the focus on embodied emissions may become less important. However, it is rather unlikely that all production of materials

INTRODUCTION

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and components will take place in Europe. It is even more unlikely that the rest of the world will have a totally clean energy system by 2050. An important challenge is therefore to ensure that most of our building materials and components are produced as close to home as possible or where the systems can be produced and transported with clean energy. Another challenge is related to the fact that the availability of technologies for using renewable energy sources is still limited. Therefore, if the goal of a zero emission society is to be achieved, energy use still needs to be drastically reduced.

Using local resources Exploiting local renewable energy sources available at the building site and exporting surplus energy to the grid is part of the general strategy to increase the share of renewable energy within the grids, thereby reducing resource consumption and associated greenhouse gas emissions. From a zero energy or zero emission building’s point of view, the grid is basically seen as a battery with infinite capacity: Surplus energy is exported to the grid and re-imported in periods of net demand. However, wide diffusion of such buildings or simply buildings with some form of onsite generation (so-called “prosumers” because they are normally consumers but at times net producers of electricity), may give rise to problems such as power stability and quality, mainly at the local distribution grid level. The fact that the building achieves a balance over the year is therefore not a guarantee that it minimizes environmental impact. Zero energy and zero emission buildings need to work in synergy with the grids and not put additional stress on their function.

Individual buildings or groups of buildings?

The ZEB Centre’s goal has been to develop solutions for individual buildings. As suggested, focusing solely on individual buildings can lead to suboptimal solutions due to high power peaks and fast load fluctuations, failing to achieve synergies between energy use and generation. For some buildings it may not even be possible to achieve the zero energy or emissions targets, either because the energy demand cannot be sufficiently reduced, such as in building renovation under architectural constraints, or because of limited access to renewable energy onsite or nearby. By considering groups of buildings, the possibilities for synergies – and at least for more cost effective energy generating installations – are often better. The focus is therefore now shifting towards zero emission neighborhoods and so-called “smart cities”. However, this requires a continued focus on the individual buildings, as the very best technologies for each building need to be used in these cases as well.

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The research activities in the ZEB Centre To address the challenges of designing and building zero emission buildings, the ZEB Centre has focused its work in five areas: advanced materials technologies, climate-adapted low-energy envelope technologies, energy supply systems and services, energy efficient use and operation, and concepts and strategies for zero emission buildings.

Several of the activities have been related to nine real building projects that include both residential, commercial, and public buildings. Most of the projects are new developments, one is a renovation project. All projects are described further in Part III. They are also used throughout the book to illustrate some of the technologies developed.

These pilot buildings show how new and existing technologies can be combined into making state-of-the-art zero emission buildings. All buildings have received a good deal of attention in the building community and outside, both in Norway and internationally.

Table 1: The ZEB pilot buildings.

Pilot Building Project

Type of Building

Powerhouse Kjørbo, Sandvika

buildings

ZEB ambition level

area

ZEB-COM÷EQ

5 000 m2

Skarpnes residential development, Arendal

5 new detached dwellings

ZEB-O

770 m2

ZEB House Multikomfort, Larvik

New detached demonstration dwelling

ZEB-OM

200 m2

Zero Village Bergen

720 new dwellings in rowhouses and apartment buildings

ZEB-O to ZEB-OM

80 000 m2

Visund, Haakonsvern, Bergen

ZEB-O÷EQ

2 000 m2

Powerhouse Brattørkaia, Trondheim

ZEB-COM÷EQ

14 000 m2

ZEB Living Lab, Trondheim

New research and demonstration dwelling

ZEB-OM*

100 m2

Heimdal VGS, Trondheim

New high school and sports hall

ZEB-OM*

25 000 m2

ZEB-COM

1 100 m2

Campus Evenstad

educational building

* Not all GHG emissions from materials are compensated for

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Figure 5: The ZEB virtual office building model and the ZEB virtual residential building model.

Source: SINTEF Byggforsk

In addition to the research activities related to the pilot buildings, there have also been a large number of studies carried out using virtual building models (so-called “shoeboxes”) – one a dwelling and one an office building. These have been used to do parameter studies of many of the relevant aspects, and these results can also be found in the various chapters in this book.

During its lifetime (2009–2017), the ZEB Centre has studied a large number of topics of importance for realizing the pilot projects as well as future zero emission buildings.

These topics range from deeply theoretical studies of how to develop nano-insulation materials to practical studies of how users perceive and use zero emission buildings and the technologies they include. Details of these studies can all be found in the chapters in this book.

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PART II

|

THE ANSWERS

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Zero Village Bergen. Illustration: Snøhetta

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CHAPTER 2 .1

THE ZEB PILOT BUILDINGS: STRATEGIES USED INGER ANDRESEN, NTNU

During the course of the ZEB Centre work, nine different pilot building projects have been initiated. At the time of writing, five of these buildings have been constructed and are in use, two of them are in the construction phase, and two are still in the design phase. An overview of the building projects is shown in table 1.

Table 1: Key data of the pilot building projects.

Pilot Building Project

ta

ZEB ambition Heated floor Annual mean ambient Annual mean horizontal level area temperature solar radiation

Type of Building

Powerhouse Kjørbo, Sandvika Renovation of two office buildings

ZEB-COM÷EQ

5 000 m2

5.9°C

960 kWh/m2

Powerhouse Brattørkaia, Trondheim

New office building

ZEB-COM÷EQ

14 000 m2

5.1°C

890 kWh/m2

Visund, Haakonsvern, Bergen

New office building

ZEB-O÷EQ

2 000 m2

7.5°C

764 kWh/m2

Campus Evenstad

New office and educational building

ZEB-COM

1 100 m2

4.7°C

663 kWh/m2

Heimdal VGS, Trondheim

New high school and sports hall

ZEB-OM*

25 000 m2

5.1°C

890 kWh/m2

ZEB House Multikomfort, Larvik

New detached demonstration dwelling

ZEB-OM

200 m2

7.6°C

974 kWh/m2

Skarpnes, Arendal

5 new detached dwellings

ZEB-O

770 m2

7.5°C

934 kWh/m2

Zero Village Bergen

6-800 new dwellings in row-houses and apartment buildings

ZEB-O

80 000 m2

7.5°C

764 kWh/m2

ZEB Living Lab, Trondheim

New research and demonstration dwelling

ZEB-OM*

100 m2

5.1°C

890 kWh/m2

* Not all GHG emissions from materials are compensated for THE ZEB PILOT BUILDINGS: STRATEGIES USED

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8.0

1200

7.0

1000

6.0

Heimdal VGS Living Lab Brattørkaia Evenstad

Visund Zero Village Bergen

kWh/m2

800

5.0 4.0

600

Yearly solar radiation 3.0

400

Yearly mean temp

2.0 200

1.0

Kjørbo

0.0 es pn

rv

ik

ar Sk

La

ad st en

Ev

rg e

m

Figure 1: Locations of the pilot building projects.

Be

ei Tr on

dh

Skarpnes

n

0

Larvik

Figure 2: Yearly mean ambient temperatures and annual solar radiation (global horizontal) for the different locations of the pilot building projects. Source: ZEB Centre

The projects are very different in size and type, ranging from single family residential buildings (Skarpnes, ZEB House Multikomfort, Zero Village Bergen, and ZEB Living Lab) to office buildings (Powerhouse Kjørbo, Powerhouse Brattørkaia, and Visund) and educational buildings (Heimdal VGS and Campus Evenstad). They are located in different climates and contexts, from the relatively temperate and moist coastal climate of Bergen in the west of Norway, via the more sunny climate of Larvik in the east, to the cold inland climate of Evenstad. The northernmost location is Trondheim. However, this climate is milder than the inland climate of Evenstad. Powerhouse Kjørbo, Powerhouse Brattørkaia, and Heimdal VGS are situated in urban/suburban environments, while the remainder of the projects have more suburban/rural locations.

In the following, some of the main characteristics and lessons learned from the pilot building projects are summarized, focusing on the design and construction processes, the design choices, and the experiences from the operation and use of the buildings.

The design and construction processes In all of the ZEB pilot building projects, an integrated energy design process has been used, as explained in chapter 2.2. This involves a process of establishing clear goals for the environmental performance, employing multi-disciplinary cooperation from day one, and using advanced tools for performance documentation throughout the process.

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Also, applying appropriate tools and contracts for follow-up in construction and operation phases has been crucial.

The design choices All projects have followed an overall design strategy of reducing the need for energy and related GHG emissions as much as possible before optimizing the energy supply systems. This is in accordance with the “trias energetica” strategy explained in chapter 2.2.

The process of design choices may be summarized in nine main issues: 1.

2.

3.

4.

5.

6.

7.

8.

9.

Location, orientation, and form Daylight and sun Material choices The building envelope – insulation and airtightness Energy efficient lights and appliances Efficient heating, ventilation, and cooling systems Measurement and control Renewable thermal energy Renewable electricity

The process of going through the design measures should not be interpreted as a linear one. This is because everything is so highly integrated; it is necessary to be able to see the interrelations between the different passive and active measures and optimize the building concept as a whole. For the sake of simplicity, however, each of the nine choices will be explained one-by-one.

Location, orientation, and form The first issue might be said to be the most efficient one, as it usually does not involve any extra investment costs – rather the contrary. Locating and orienting the building according to the availability of sunshine and daylight, the prevailing wind, and sources of pollution from traffic, etc., creates the basis for utilization of renewable energy and for the ventilation concept. The form and layout of the building have a pronounced impact on the final energy use and GHG emissions. A compact and efficient building with a high degree of area efficiency and spaces for mixed use will naturally lead to lower emissions. Requirements with respect to flexibility in use may be challenging, as they may both limit and enhance the possibilities for achieving low life cycle emissions. It is usually necessary to find a trade-off that balances the investment in a high degree of flexibility with the efficient tailor-made design.

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Figure 3: Analysis of the building’s form and solar radiation falling on different surfaces, performed during the concept design phase of Powerhouse Brattørkaia.

Illustration: Snøhetta Kwh/m2

Gradient of PV panel

935 530 119

Årlig solinnstråling på fasaden genererer fordelingen av vindusfelt og solceller (PV) på fasaden Høy innstråling gir lite vindusareal og høy andel solceller. Lav innstråling gir større vindusfelt og mindre solceller.

The different ZEB pilot building projects have all considered the location, orientation, and form in different ways. Of course, these choices are not based on considerations of energy and emissions only, as architectural issues will always be important. Architectural considerations and design choices from the pilot building projects are explained in chapter 2.3.

Figure 3 shows a step in the analysis of solar radiation availability done in the concept design phase of Powerhouse Brattørkaia.

Daylight and sun Passive utilization of daylight and sun is a means to save energy for heating, cooling, and lighting. Strategies include the careful placement and orientation of buildings, optimization of the envelope layout, zoning, and careful selection of building materials and products.

All the pilot building projects have utilized such strategies in different ways. The strategies need to be tailored to the individual sites and building use. For schools and office buildings, the main challenge is to avoid overheating during the day, while at the same time allowing for ample daylight to penetrate into the space. Thus, the facades facing east, west, and south are equipped with dynamic solar shading. Most common are exterior movable blinds or screens, but other more advanced systems are also used. The Heimdal VGS will have electrochromic glazing in some areas, allowing for continuous control of solar gains, daylight, and view without any movable parts. In the Visund office building, a Venetian blind system with daylight-guiding lamellas is installed in the upper part, and a standard Venetian blind in the lower part of the window, see figure 4. The blinds consist of two sections that can be independently tilted, making it possible to close the lower part of the blind while keeping the upper part open. This allows for daylight penetration deep into the room even when there is a need to block out direct radiation.

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Figure 4: Illustration of principle for daylightguiding blinds (left) and photo of the blinds installed in the Visund office building (right).

Source: ZEB Centre.

Photo: Forsvarsbygg/ Åsmund V. Sjursen

Material choices For a project where the operational energy use has been minimized, the relative share of embodied energy/emissions may be significant. For ZEB pilot buildings, the embodied energy and emissions will typically represent half of the total life cycle emissions, at least if measures have been applied to minimize them.

In all of the ZEB pilot building projects there have been efforts to reduce embodied energy/emissions in materials and constructions. In particular in the projects with ambition levels ZEB-OM and higher, design for low material emissions has been a prime focus. The measures have included reducing the amounts of materials used, reusing materials and constructions, using recycled materials, renewable materials, low-maintenance materials and systems, and locally sourced materials. This is described in more detail in chapter 2.6.

Figure 5 shows the calculated GHG emissions from different construction parts in three of the pilot building projects. In the Powerhouse Kjørbo project, the emissions from superstructure, structural deck, and groundwork and foundations are almost zero, because most of the existing structure was kept. In the ZEB House Multikomfort, the emissions from the superstructure are low, because the structure is made of wood. In Heimdal VGS, it is obvious that the inner walls contribute a large share of the emissions.

This is due to requirements with respect to sound, fire, and transparency. Also, the superstructures in Heimdal VGS have high emissions due to large spans, which require structures with high carrying capacity, especially for the sports hall. Powerhouse Kjørbo and ZEB House Multikomfort both have relatively large PV systems, something which is reflected in the large share of emissions for these.

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kg CO2-ekv/(m2 yr)

Figure 5: Calculated greenhouse gas emissions from materials use in three of the pilot building projects. Emissions are calculated in kg CO2-ekv/m2 heated floor area leveled over a life-time of 60 years. Source: ZEB Centre

PH Kjørbo

ZEB Multikomfort

Heimdal VGS

The building envelope – insulation and airtightness All of the pilot building projects have envelopes that are well insulated and airtight.

Their energy use for heating is designed to be similar to the Norwegian passive house standard or lower. U-values of exterior walls range from 0.10–0.15 W/(m2K), while the roofs typically have somewhat lower U-values. Most projects use mineral wool, but reflecting foils (ZEB House Multikomfort) and insulation made from wood fiber (Campus Evenstad) have also been used. Efforts have been made to minimize thermal bridges by having good thermal insulation on the exterior of the structural elements.

In some cases, special insulation materials such as VIP and reflective foils have been applied to optimize the envelope construction. All projects have windows with U-values lower than 0.8 W/(m2K), e.g. triple glazing with two low-E coatings, gas fillings, warm edge seals, and insulated frames.

There has been strong emphasis on achieving continuous air and moisture barriers in the building envelopes. The moisture barrier is placed behind an interior layer of insulation to protect it from being damaged. In places where the air and moisture barriers are perforated by ducts or pipes, cuffs and/or tape are used to avoid leakages.

The air leakage number, n50, was designed to be below 0.6 ACH (air changes per hour) for all the buildings. It is also required that the air leakage be measured as-built. For the Powerhouse Kjørbo, the measured n50 value was 0.24, while for the Visund office building it was 0.1 ACH.

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Energy efficient lights and appliances Having lights and appliances that require little energy for operation is important in all low energy buildings. In office buildings and other buildings with high internal loads, it is especially important to have efficient equipment to avoid excessive heat loads. In the ZEB office buildings and educational buildings, LED lights, in combination with daylight and occupant sensors to minimize use, are now being used to a large degree.

In the residential buildings, A+++ labeled white goods are used, along with hot-fill washing machines to allow for utilization of hot water produced from heat pumps or solar thermal systems.

LED

A+++

Efficient heating, ventilation and cooling systems (HVAC) HVAC consists of a number of different strategies that are closely interlinked. They are also very dependent on the previous strategies, i.e. that the heating and cooling loads have been minimized through optimization of form, envelope, and internal gains. If the building has been carefully designed by applying appropriate passive measures such as those described above, it is possible to design simplified HVAC systems that require very little energy for operation and that have lower investment costs than conventional systems.

For example, if the facades are very well insulated and the heating load is low, the heat distribution system may be much more compact than in a conventional building. In all the ZEB residential buildings, there is only one radiator per floor, centrally located near the technical room. This allows for shorter distribution pipes.

In the cold climate of Norway, an efficient ventilation system relies on heat recovery during the cold season. All of the ZEB pilot buildings have rotary heat exchangers, and design values of annual recovery rates range between 84 and 90%.

The energy use for fans is minimized through designing systems with low pressure drops, including demand control, short and spacious distribution channels partly relying on using secondary spaces such as corridors as return air channels, as well as taking advantage of thermal buoyancy for extracting air. In addition, ventilation air volumes are minimized by utilizing thermal mass to avoid overheating, and by using low-emitting materials to minimize indoor air pollutants. SFP-factors (Specific Fan Power) vary between 0.5 and 1.5 kW/(m3s) as design values.

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Figure 6: Example of a visualization system showing the real time energy generation from the photovoltaic system in Powerhouse Kjørbo.

Photo: Asplan Viak

Measurement and controls All the pilot buildings have advanced measurement and control systems making it possible to follow up and visualize the energy use for different purposes. Energy use for space and water heating, ventilation, cooling, lights, and appliances are measured separately.

Renewable thermal energy Having reduced the energy use and emissions as much as possible, one should look for renewable thermal systems to supply the remaining heating and cooling loads (if any).

Figure 7 shows the net energy demand of the ZEB pilot building projects, calculated according to NS 3031:2007 Energy Performance of Buildings. It is obvious that the space heating and cooling demands are very small. The energy demand for domestic hot water is dominant in the residential buildings.

kWh/(m2 year)

Figure 7: Calculated yearly net energy demand in kWh/m2 heated floor area for the ZEB pilot buildings.

Source: ZEB Centre

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Seven of the ZEB pilot buildings have or will have heat pump systems. This includes ground source heat pumps (Skarpnes, ZEB Living Lab, ZEB House Multikomfort, Powerhouse Kjørbo, and Heimdal VGS) and seawater heat pumps (Visund and Powerhouse Brattørkaia). The ZEB House Multikomfort and the ZEB Living Lab also have solar thermal systems. The building at Campus Evenstad will have a CHP system based on gasification of wood chips, and the Heimdal VGS will probably have a CHP machine based on biogas. The ZEB House Multikomfort also has a grey water heat recovery system.

Excess heat from servers is also utilized in the non-residential buildings. Where district heating is available, this is used for auxiliary heating.

Renewable electricity The remaining energy use/emissions need to be compensated for by onsite generation of renewable electricity. For this, there are basically three different technologies that have been considered in the ZEB pilot building projects: photovoltaics, wind power, and CHP systems. Wind power was not selected in any of the projects because of low energy yields due to insufficient wind speeds at the sites. In eight of the nine projects, photovoltaic systems have been chosen. All are based on crystalline silicon technologies with module efficiencies ranging from 16 to 21%. All are grid connected, and one has battery storage for electric car charging (ZEB House Multikomfort). The annual output of the PV systems has been calculated to be from 113 to149 kWh per m2 module area.

Summary A range of different technologies were applied in the pilot building projects. However, all the projects have followed the overall design strategy of first, reducing the need for energy as much as possible, and thereafter applying renewable energy technologies to compensate for the remaining energy and greenhouse gas emissions. Overall, the projects demonstrate that it is possible to reach different levels of zero emission buildings by combining passive and active measures into an integrated whole.

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Photo: Tom A. Kolstad/Aftenposten

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practitioners looking for ways to contribute to a sustainable future.

A.G. HESTNES AND N.L. EIK-NES (EDS.)

The book describes some of the key knowledge areas needed when designing, building, and operating zero emission buildings. It should be read by students of architecture and engineering as well as

ZERO EMISSION BUILDINGS

This book shows what can be achieved when researchers and practitioners work together to develop the building performance level of tomorrow, but needed today. The book is based on the research and development activities performed in the Research Centre on Zero Emission Buildings (the ZEB Centre, www.zeb.no) from 2009 to 2017.

Emissions of CO2 and other greenhouse gases must be reduced to limit global warming. Thus, the goal of the ZEB Centre has been to develop knowledge, competitive products, and solutions for existing and new buildings whose production, operation, and demolition give zero emissions of greenhouse gases while also considering the users’ needs for comfort and flexibility. The results presented here are based on research as well as experience from the development of nine real demonstration buildings.

ZERO EMISSION BUILDINGS

ISBN 978-82-450-2055-7

Omslag med klaffer NY 08_12.indd 1

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