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Related Titles

Athienitis, A., O'Brien, W. (eds.)

Modeling, Design, and Optimization of Net-Zero Energy Buildings


Print ISBN: 978-3-433-03083-7

oBook ISBN: 978-3-433-60462-5

ePDF ISBN: 978-3-433-60463-2

eMobi ISBN: 978-3-433-60464-9

ePub ISBN: 978-3-433-60465-6

Hadorn, J.-C. (ed.)

Solar and Heat Pump Systems for Residential Buildings


Print ISBN: 978-3-433-03040-0

oBook ISBN: 978-3-433-60483-0

ePDF ISBN: 978-3-433-60484-7

eMobi ISBN: 978-3-433-60482-3

ePub ISBN: 978-3-433-60485-4

Edited by

François Garde

Josef Ayoub

Daniel Aelenei

Laura Aelenei

Alessandra Scognamiglio

Solution Sets for Net Zero Energy Buildings

Feedback from 30 Net ZEBs worldwide

Wiley Logo

About the Editors

Photograph depicting Dr. François Garde.

Dr. François Garde is a Professor of Building Physics at the Faculty of Engineering ESIROI and Senior Researcher at the PIMENT Laboratory, University of La Reunion. At a political level, he is also responsible for the sustainable policy at the university. He is an engineer graduated from the French “Grande Ecole” Ecole Centrale de Lyon (1989) and has a MBA in company management. After three years in an engineering practice, he achieved his PhD in 1997 as a research engineer in the French Public Utility “Electricité de France” in Reunion Island. His main fields of activities are Net Zero Energy Buildings and Communities in the tropics, thermal comfort and Post Occupancy Evaluation. He is a French recognized expert in the design of low/net zero energy buildings in the tropics. He is the former project manager of thermal standards and research national projects focusing on tools and methods for the design of low/net zero energy buildings (ECODOM 2000, PERENE 2009, ENERPOS 2009). He is the former Sub-Task C Leader of the IEA SHC Task 40 EBC Annex 52 “Towards Net-Zero Energy Solar Buildings” (2009-2013) and a French national expert in the IEA SHC Task 51 “Solar Energy in Urban Planning” (2013-2017).

Photograph depicting Josef Ayoub.

Josef Ayoub is a Senior Energy Science and Technology Planning Advisor at the Department of Natural Resources Canada, at the CanmetENERGY technology research center in Varennes, Quebec. He participates in several departmental portfolios under the Government of Canada's Program on Energy Research and Development in the technology areas of integration of renewable distributed energy resources into net zero energy buildings. He is the former Operating Agent of the IEA SHC Task 40 EBC Annex 52 (“Towards Net-Zero Energy Solar Buildings”) (2009–2013) and the Former Network Manager of the Canadian NSERC Smart Net Zero Energy Buildings Strategic Research Network (2011–2014). He was also Canada's delegate to the Executive Committee of the IEA Photovoltaic Power Systems Program (2005-2012), and is presently Canada's Alternate Delegate to the Executive Committee to IEA International Smart Grid Action Network.

Photograph depicting Dr. Laura Aelenei.

Dr. Laura Aelenei is a senior researcher at the Energy Efficiency Unit of National Energy and Geology Laboratory and Invited Professor of Energy Efficiency studies at the Master of Energy and Environment Engineering at the Faculty of Sciences of the University of Lisbon (FCUL). She is a Civil Engineer, holding a Master Degree on Buildings Rehabilitation and a PhD in Civil Engineering (heat and mass transfer, fluid dynamics through building ventilated envelope systems). She is involved in several national and international research projects as participant or coordinator and participated in buildings national regulation commissions. She was participating as national expert in the International Energy Agency (IEA) SHC Task 40/ECBCS Annex 52 “Towards Net Zero Energy Solar Buildings.” She is reviewer for international Journals: Renewable Energy Journal, Energies and ASME Journal of Solar Energy Engineering: Including Wind Energy and Building Energy Conservation, evaluator of European Cost project proposals. She is co-author of six scientific books (national and international) and author of more than 50 research papers published in scientific journals, conferences and communications.

Photograph depicting Dr. Daniel Aelenei.

Dr. Daniel Aelenei is a professor of building physics and building technical services at the Department of Civil Engineering and senior researcher at Center of Technology and Systems (CTS) of the “Universidade Nova” of Lisbon, Portugal. He is responsible for graduate and postgraduate courses and for supervision of dissertations in energy efficiency of buildings. He studied civil engineering at the Technical University “Gheorghe Asachi” of Iasi, Romania, and in 2004 achieved his PhD at the “Instituto Superior Técnico” of University of Lisbon, Portugal, in the field of passive cooling design and technologies for housing. He is active participant in the Cost Action TU1403 (“Adaptive Façade Network”) and in the IEA EBC Annex 67 (“Energy Flexible Buildings”) and has participated in the IEA SHC Task 40 EBC Annex 52 (“Towards Net-Zero Energy Solar Buildings”).

Photograph depicting Dr. Alessandra Scognamiglio.

Dr. Alessandra Scognamiglio is a researcher in the Photovoltaic Systems and Smart Grids Unit at the ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development). She holds a PhD in Technologies for Architecture and Environment from the Second University of Naples Luigi Vanvitelli, 2010, a Master in Architecture from the University of Naples Federico II, 1998, and is a licensed architect (Naples, 1998). Her main fields of activity are: Building Integrated Photovoltaics (BIPV), Photovoltaics and sensitive landscapes, Net Zero Energy Buildings and Smart Cities. Since 2003, she has been a teacher at the Italian National Institute of Architecture for a post graduate master course in “Designer of sustainable architectures.” She is participating in European projects aimed at the development of special photovoltaic components for buildings. She is also involved in several IEA research collaborations, particularly: 2008–2012 IEA SHC Task 41 “Solar Energy and Architecture”; 2008–2013 IEA SHC Task 40-EBC Annex 52 “Towards Net Zero Energy Solar Buildings, 2013–2017 IEA SHC Task 51 “Solar Energy in Urban Planning, and since 2015 in the IEA PVPS Task 15, “Enabling framework for BIPV acceleration”. Since 2008 she has been topic organizer of the European Photovoltaic Solar Energy Conference (EUPVSEC) focusing on Photovoltaics and Architecture. She is an active member of the COST RELY action TUI 401 “Renewables and Landscape quality.”

List of Contributors

Daniel Aelenei

Universidade Nova de Lisboa

Faculty of Science and Technology

Department of Civil Engineering

2829-516 Caparica


Laura Aelenei

Unidade de Energia no Ambiente Construído – UEAC

Laboratório Nacional de Energia e Geologia – LNEG

Estrada do Paço do Lumiar Edifício Solar XXI

1649-038 Lisboa


Josef Ayoub

CanmetENERGY/Innovation and Energy Technology Sector

Natural Resources Canada

1615 Lionel-Boulet Blvd

Varennes, Quebec J3X 1S6


Shaan Cory

Beca Wellington Office

85 Molesworth Street

Thorndon 6011


New Zealand

Eduard Cúbi

University of Calgary

Schulich School of Engineering

2500 University Drive NW

Calgary, Alberta T2N 1N4


Aymeric Delmas

PIMENT Laboratory

Université de La Réunion

Campus universitaire Sud

117 rue Général Ailleret

97430 Le Tampon

La Réunion


Michael Donn

Victoria University of Wellington School of Architecture

PO Box 600

139 Vivian St.


New Zealand

François Garde

PIMENT Laboratory

Université de La Réunion

Campus universitaire Sud

117 rue Général Ailleret 97430 Le Tampon

La Réunion


Jun-Tae Kim

Department of Architectural Engineering & Graduate Program of Energy Systems Engineering

Kongju National University

1223-24 Cheonandae-Ro


Chungnam Province 31080

Republic of Korea

Jonathan Leclère

Laboratoire de Génie Electrique de Grenoble

G2Elab Bâtiment GreEn-ER

21 avenue des martyrs CS 90624

38031 Grenoble Cedex 1


Aurélie Lenoir

IMAGEEN8 rue Henri Cornu BP 12005

97801 Saint-Denis Cedex 9

La Réunion


Ghislain Michaux

LaSIE, Pôle Sciences et Technologie

Avenue Michel Crépeau

17042 La Rochelle Cedex 1


Eike Musall

Bergische Universität Wuppertal

Faculty of Architecture

Building physics and technical services

Haspeler Straße 27

42285 Wuppertal


Masa Noguchi

The University of Melbourne

Faculty of Architecture Building and Planning

757 Swanston Street

Victoria 3010


Federico Noris

Institute for Renewable Energy

EURAC Research

Viale Druso n1

39100 Bozen/Bolzano


Eric Ottenwelter

IMAGEEN8 rue Henri Cornu

BP 12005

97801 Saint-Denis Cedex 9

La Réunion


Harald N. Røstvik

ProfessorUniversity of Stavanger


Jaume Salom

Institut de Rercerca en Energia de Catalunya (IREC)

Jardins de les Dones de Negre 1, 2a pl.

08930 Sant Adrià de Besòs



Alessandra Scognamiglio

ENEA CR Portici

P.le E. Fermi

80055 Portici (Napoli)


Kim Jun Tae

Kongju National University

Department of Architectural Engineering & Graduate Program

of Energy Systems Engineering

1223-24 Cheonandae-Ro


Chungnam Province 31080

Republic Of Korea

Michel Tardif

Housing & Buildings R&D


Innovation and Energy Technology Sector

Natural Resources Canada

1 Haanel Drive

Ottawa, Ontario K1A 1M1 Canada

David Waldren


3 Albert Coates Lane

Melbourne, Victoria 3000


Tobias Weiss

AEE INTECFeldgasse 198200 GleisdorfAustria

Kim Wittchen

Aalborg University

Danish Building Research Institute

Dr. Neergaards Vej 15

2970 Horsholm


Stephen Wittkopf

Lucerne School of Engineering and Architecture

Campus Horw

Technikumstrasse 21

6048 Horw, Lucerne


IEA Solar Heating and Cooling Programme

The Solar Heating and Cooling Technology Collaboration Programme was founded in 1977 as one of the first multilateral technology initiatives (“Implementing Agreements”) of the International Energy Agency. Its mission is “to enhance collective knowledge and application of solar heating and cooling through international collaboration to reach the goal set in the vision of solar thermal energy meeting 50% of low temperature heating and cooling demand by 2050”.

The members of the IEA SHC collaborate on projects (referred to as “Tasks”) in the field of research, development, demonstration (RD&D), and test methods for solar thermal energy and solar buildings.

A total of 57 projects have been initiated, 49 of which have been completed. Research topics include:

In addition to the project work, there are special activities:

Country Members

Australia Germany Spain
Austria Italy South Africa
Belgium Mexico Sweden
Canada Netherlands Switzerland
China Norway Turkey
Denmark Singapore Portugal
European Commission Slovakia United Kingdom

Sponsor Members

European Copper Institute International Solar Energy Society
Gulf Organization for Research and Development

For more information on the IEA SHC work, including many free publications, please visit


This work was produced in the context of a joint collaboration between approximately 75 national experts from 19 nations in Europe, North America, Oceania, and Southeast Asia of the International Energy Agency (IEA), under the framework of the IEA Solar Heating and Cooling (SHC) and Energy in Buildings and Communities (EBC) Technology Collaboration Programs. The joint SHC Task 40/EBC Annex 52 (T40A52) “Towards Net-Zero Energy Solar Buildings” sought to study current net-zero, near-net-zero and very low energy buildings and to develop a common understanding of a harmonized international definitions framework, tools, innovative solutions, and industry guidelines to support the conversion of the Net ZEB concept from an idea into practical reality in the marketplace. This Task/Annex pursued optimal integrated design solutions that provided good indoor environment for both heating and cooling situations. The process recognized the importance of optimizing a design to meet the functional requirement, reducing loads, and designing energy systems that pave the way for seamless incorporation of renewable energy innovations, as they become cost effective. To achieve these results, the National Experts met twice annually at a hosting member country to coordinate the R&D activities and advance the work plan comprised of the following four major activities:

  1. Subtask A dealt with establishing an internationally agreed understanding on Net ZEBs based on a common methodology. This was done by reviewing and analyzing existing Net ZEB definitions and data with respect to the demand and the supply side; studying grid interaction (power/heating/cooling) and time-dependent energy mismatch analysis; developing a harmonized international definition framework for the Net ZEB concepts considering large-scale implications, exergy, and credits for grid interaction (power/heating/cooling); and, developing a monitoring, verification and compliance guide for checking the annual balance in practice (energy, emissions, and costs) harmonized with the definition;
  2. Subtask B aimed to identify and refine design approaches and tools to support industry adoption. This was done by conducting work along four major R&D streams: (i) in documenting and analyzing processes and tools currently being used to design Net ZEBs and under development by participating countries; (ii) assessing gaps, needs, and problems to inform simulation engine and detailed design tool developers of priorities for Net ZEBs; (iii) qualitative and quantitative benchmarking of selected tools; and (iv) selecting four case study buildings to conduct a detailed analysis of simulated/designed vs. actual performance, and proposing the redesign/optimization of these buildings;
  3. Subtask C focused on developing and testing innovative, whole building net-zero solution sets for cold, moderate, and hot climates with exemplary architecture and technologies that would be the basis for demonstration projects and international collaboration. This was achieved by documenting and analyzing current Net ZEBs designs and technologies, benchmarking with near Net ZEBs and other very low energy buildings (new and existing), for cold, moderate, and hot climates considering sustainability, economy, and future prospects using a projects database, literature review, and practitioner input (workshops); developing and assessing case studies and demonstration projects in close cooperation with practitioners; investigating advanced integrated design concepts and technologies in support of the case studies, demonstration projects, and solution sets; and developing Net ZEB solution sets and guidelines with respect to building types and climate, and to document design options in terms of market application;
  4. Subtask D was crosscutting work that focused on dissemination to support knowledge transfer and market adoption of Net ZEBs on a national and international level. This was accomplished by establishing a Net ZEB web page within the IEA SHC/EBC Programmes' framework and a database that can be expanded and updated with the latest projects and experiences; transferring the outputs (reports, sourcebooks, guidelines, other) to national policy groups, industry associations, utilities, academia, and funding programs; participating in national and international workshop, seminars, and industry exhibitions highlighting the results and activities of the Task/Annex contributing high-quality technical articles and features in journals to stimulate market adoption; and, establishing an education network of highly qualified people that will continue the work in the field in their future endeavors.

I am pleased to present the research results of Subtask C compiled in this volume of work entitled “Solution Sets from Net Zero Energy Buildings: Feedback from 30 Net ZEBs worldwide” as a major accomplishment in this field of research. Building energy design is currently going through a period of major changes driven largely by three key factors and related technological developments: (i) the increasingly widespread adoption in most OECD member countries and by influential engineering societies, such as ASHRAE, of net-zero energy as a long-term goal for new buildings; (ii) the need to reduce the peak electricity demand for buildings through optimal operation; and (iii) the need to efficiently integrate advanced energy technologies into buildings, such as photovoltaic/thermal systems, windows with semitransparent photovoltaic glazing, controlled shading/daylighting devices, and integrated thermal storage. This body of work encapsulates the many and varied lessons learned of designing, building and operating net-zero energy buildings by government research organizations, international and regional research centers, academia, and industry. I am confident this book will find many interested readers.

Josef Ayoub

Former Operating Agent, IEA SHC Task 40/EBC Annex 52

Senior Planning Advisor, Energy Science & Technology

CanmetENERGY | Natural Resources Canada | Government of Canada




François Garde: The work and the participation of the French experts in the IEA SHC Task40 EBC Annex 52 was entirely funded by ADEME (the French Environment and Energy Management Agency). The French participants would like to thank ADEME for its financial support and in particular Pierre Hérant, Head of the Building Department of ADEME and Executive Committee Member of the International Energy Agency.

Josef Ayoub: The Government of Canada provided partial funding for this work under two major programs: the Program of Energy Research and Development (PERD), a federal inter-departmental program operated by the Department of Natural Resources Canada, supported the position of the Operating Agent for five years to coordinate the work and lead this international network of researchers; and the recently ended Canada's Climate Change Action Plan EcoENERGY Innovation Initiative (EcoEII), aimed at supporting energy technology innovation to produce and use cleaner energy more efficiently. Both the PERD and the EcoEII programs funded the R&D work and the participation of all National experts from Canada in the IEA SHC Task 40 EBC Annex 52.

Laura Aelenei: The National Laboratory of Energy and Geology supported the work and participation of this National expert in the IEA SHC Task 40 EBC Annex 52. Laura Aelenei thanks in particular the Director of Energy Laboratory, Doctor Helder Gonçalves for his permanent support and encouragement to accomplish this work.

Daniel Aelenei: The research reported in this publication was supported by the Universidade Nova de Lisboa from the Faculty of Science and Technology research scheme.

Alessandra Scognamiglio: The participation of ENEA in the IEA SHC-EBC Task 40-Annex 52 was funded by the national programme « Ricerca di sistema elettrico ».

The editors would also like to thank Mr. Gerald Parnis, Research Associate at Center for Zero Energy Building Studies at Concordia University in Montreal, Quebec Canada, for his exhaustive input as the production editor of this work.


François Garde,1 Michael Donn,2 and Josef Ayoub3

1PIMENT Laboratory, Université de La Réunion, Campus universitaire Sud, 117 rue Général Ailleret, 97430 Le Tampon, La Réunion, France

2Victoria University of Wellington School of Architecture, PO Box 600, 139 Vivian St., Wellington, New Zealand

3CanmetENERGY/Innovation and Energy Technology Sector, Natural Resources Canada, 1615 Lionel-Boulet Blvd, Varennes, Quebec J3X 1S6, Canada

1.1 Why Another Book on Net Zero Energy Buildings?

This book is the principal output of a major international research project under the auspices of the International Energy Agency (IEA) Solar Heating and Cooling (SHC) and Energy in Buildings and Communities (EBC) Technology Collaborating Programs joint SHC Task 40/EBC Annex 52: Towards Net Zero Energy Solar Buildings [1]. The focus of the project was to examine the performance in use of net-zero energy buildings (Net ZEBs) across the globe in order to understand the strengths and weaknesses of the design solution sets adopted. The fundamental contribution of the part of the project described in these pages was this examination of many different built and functioning buildings and the general lessons about Net ZEBs that can be drawn.

At heart therefore, this book is an examination of 30 case studies. These projects all aimed to equalize their small annual energy needs, cost-effectively, through building integrated heating/cooling systems, power generation and interactions with utilities. These buildings had to meet strict criteria for inclusion in this analysis, beyond merely being labeled by their designers or promoters as “green” or “energy positive” or “net-zero energy.” The most important among these criteria was the insistence that a minimum of one full year of metered performance data was available for analysis. In addition, the research team sought to identify buildings whose architecture and combinations of technologies formed “solution sets” which could potentially be useful exemplars for other design teams seeking to build a net-zero energy building.

The world of modern architecture has flirted for the past fifty years with idea of bioclimatic design and autonomous architecture. Too often these have been one-off exercises serving only a research agenda, and not integrated into the mainstream of architecture or society. As such, they have been incredibly useful learning vehicles, but have found little acceptance outside of a small world of academics and research scientists. The underlying concept of a Net ZEB is that it should be widely accepted and it should connect to community and national energy grids.

The buildings in this study, while excellent exemplars, cannot be copied or adopted without careful analysis of each new design situation. The analysis in this book is directed to assisting the readers' understanding of the circumstances of each exemplar and of their design and performance constraints in order that designers of future Net ZEBs will not require the same level of fundamental analysis undertaken in these buildings. The buildings documented here are pioneers in their society or circumstances. They incorporate measures and technologies that are at the leading edge of technical innovation for their time and are all to that extent repeatable. The goal of this book is to reduce the impression of risk for the new investor. Documenting not just the technology, but also the success of that technology in real buildings is intended to assist those investing in new buildings to understand how best to apply the technology themselves.

The book eschews presentation of the data in a catalog of case studies. The approach has been to examine as carefully as possible the lessons that can be drawn from these individual cases. The complete case study data collected for the analysis is however available online in a standardized database format to enable the reader to extract their own information [2]. No particular building type has been focused on: the list includes both single family residential and commercial/institutional buildings. It is conventional in a book of this type to ascribe other broader world-view rationales for the writing. It is clear for example that this book is arriving at a time when in much of Europe and in the USA governments are setting or have set ambitious goals for new buildings to be designed to be net zero energy by 2030: in the USA within the Energy Independence and Security Act of 2007 (EISA 2007) and, at the European level within the “recast” Directive on Energy Performance of Buildings (EPBD).

The EISA 2007 supports a goal of net-zero energy for all new commercial buildings by 2025 and notes a longer term goal of net-zero for all U.S. commercial buildings by 2050 [3], whereas the EPBD proposes “nearly zero” energy buildings from 2020 for all new buildings [4]. It is our belief that this book will provide one of the tools to enable designers to achieve and even exceed these political goals.

It is not our intention to repeat the rationales or catalog government approaches of these or other government initiatives. Rather, it is anticipated that the reader picked up this book in the full understanding of this international, and their own local context, and wants to learn from those who have built what works and what does not work among the many candidate design techniques and technologies to be found in the many text books describing Building Physics, Bioclimatic Architecture, or low energy Environmental Systems Design.

1.2 What is a Net Zero Energy Building?

1.2.1 IEA SHC Task 40/EBC Annex52: Towards Net Zero Energy Solar Buildings

Over 82 national experts from 19 different countries have been directly involved in this IEA research collaboration for over a 5-year period (October 2008 – September 2013). Their goal was to support the conversion of the Net ZEB concept from an idea into practical reality in the marketplace. This source book and the associated datasets provide realistic case studies of how Net ZEBs can be achieved. Demonstrating and documenting real projects has the ultimate goal of lowering industry resistance to adoption of these concepts.

The research team examined the many variations on the theme of Net Zero Energy that could be found in the literature as well as in the different participating countries. The goal was to discover a common language, and common performance metrics for what at first seems a simple concept: a Net ZEB is an energy grid-connected building which on an annual basis contributes as much energy to the grid(s) to which it is connected as it draws from the grid(s). It is not an autonomous building standing alone and separate from a community. Rather, it is an integral part of that community, and its energy grids. An energy grid could be a part of a local or national electricity grid. Equally, it could be a district heating or cooling system. A further corollary of this derivation in this project is that the required on-site generation is from renewable energy sources – solar, bio-fuels, wind and so on. Merely creating a building with an on-site fossil fuel fired electricity generator is not creating a building that fits the net-zero definition adopted in this research. An associated goal of this IEA work was to develop a clear definition and international agreement on the measures of building performance that could inform “zero-energy” building policies, programs and industry adoption.

However, a viewing this simplistic description reveals a number of variants – each of which has a place, depending on the type of analysis contemplated. The research team was able to identify and classify these different variants, but not to develop a single internationally applicable definition, because not would satisfy all of the participants nor their country-specific needs. The issues that arise are concerned with: mismatch of time of peak use and time of peak generation; definition of time scales for the analysis – one year, or a lifetime; definition of boundaries – where to place the energy generation, on site, or near site.

The definitions work was the subject of a separate research task within the overall research framework. The research output from this work has produced a number of key outputs clarifying and documenting these definitions including a source book published by DETAIL Green Books [5]. The Net-Zero Energy Balance tool developed in this work is also used in this book to document each building in a consistent manner. Other participants in the IEA task worked on documenting and developing tools for use in the design and analysis of Net ZEBs. Their work was published in a second source book by Ernst und Sohn (a Wiley Brand) [6].

1.2.2 Target Audience: Designers and Their Clients

The purpose of this book is to provide an easy to read guide to the principles and benefits of ultrahigh performance buildings. These buildings are targeted at producing at least as much energy as they consume on an annual basis. They are therefore performing at a far more extreme level than typical buildings in a particular climate or location. To this extent, they are radical departures from the normal practice of most designers at present. The goal is to transform standard architectural practice from its past reliance on energy consumption to a mixed consumption and generation mode of operation. This requires a paradigm shift on the part of much architectural practice. It is not our intention to suggest that all architects need to change. Rather as researchers we have sought to learn from those willing to experiment – those who push the boundaries of standard practice.

The structure, the content and the analysis in the book is therefore aimed at informing the interested designer. Within its pages there should be sufficient information for the designer who wishes to work on a net zero energy building to understand:

  1. — What is the mix of skills required in the design team to achieve a Net Zero outcome?
  2. — What are the important design priorities in the architectural form and planning?
  3. — What are the passive energy design approaches which are appropriate for the climate, location, and society and building type?
  4. — What are the significant energy efficiency techniques and technologies for the climate, location, and society and building type?
  5. — And what are the energy generation technologies that might convert a low energy building into an energy positive building?

Crucially important in all this analysis is the energy use information from real buildings. While it is anticipated that most building owners and investors will not read this book from cover to cover, and are unlikely to be interested in the design principles it is expected that they will be highly interested in the functional details. Do these buildings deliver? Are they really low energy? Do they deliver the claimed superior comfort? Are users really much happier than in conventional buildings? The packaging of this design guide on the basis of real data should deliver on this client need.

Designers Require Simple Solutions and Low Risk Design Concepts

If Net ZEBs are to become standard practice, then design practice needs to change. The lessons of all these buildings are that they are the results of quite intensive collaborations. Design teams are adamant this intensity of collaboration is hugely important. They are also atypical of current practice. Often these design teams have met well prior to any architectural concept sketch and established a set of parameters and constraints for the building. Style is part of this. Function is part of this. Cost is an essential element. None takes precedence. The conventional notion of an architect developing a design and handing it over to an engineer to make it work is abandoned. The engineer is a part of the design process from the outset. No design phase has an engineer or analyst adding 'heating and cooling and lighting energy consuming services'.

However, the level of analysis and design team involvement observable in the case study buildings is not thought feasible for every building. This is one of the purposes of this book: to simply and thus make feasible in everyday practice this advanced building design process. The design team that works together often, and works on similar buildings in similar climates will learn what works and then be able to apply and develop the design ideas more than the examples in this book. This is a far simpler process than has had to be undertaken for these pioneer buildings. It is also a far lower risk. Design teams in our litigious society cannot afford to take risks: dissatisfied clients sue; court cases discourage new clients. The purpose then of the design analysis in this book is to simplify the process from that of the experimental exploratory designs presented in the case studies to the level where standard practices, offering standard design fees might feasibly be able to deliver high performance Net ZEBs.

Clients Want Guaranteed Performance

In normal building practice, the client is the person or institution risking their resources. In such circumstances, it is only the rare client, with other motives than the delivery of the building itself, who is prepared to invest in a technology or building design approach that has not been shown to work elsewhere. The energy performance of a building is typically a relatively small expense compared to the initial investment. Achievement of Net ZEB performance requires careful investment. There is a risk that the return on investment may take many years to break even. The case studies in this project have all examined this question within very different societies and financial structures. In some cases they were experimental projects where there was additional funding for the experiment. In other cases the extra funds were essentially part of the promotional budget of the firm interested in ensuring that their building matched the future proof image they wished to project. Yet others were interested to invest a little more upfront in order sell their buildings as modern or advanced and thus seek a rental or sales premium relative to the rest of the market.

The goal of this book is to enable even the most timid of investors to understand the technologies and design approaches that must be invested in order to achieve Net ZEB performance. When this average investor is able to quantify or understand how small the added risk of investment is in net zero energy performance compared to the already substantial risk they are undertaking in investment in a building, then Net ZEBs will be mainstream. The purpose of including real energy data in this book, along with local energy costs and the total investment cost per square meter is to provide data that the investor understands. The family investing their life savings in a house, or the institution considering how best to make a return on constructing an office building share this same interest: what will the added expenditure on net zero energy performance, if there is any, return in the way of performance.

1.3 Structure of This Book

Chapter 2 focuses on addressing the unique combinations of energy efficiency measures and renewable energy sources, forming a “solution set,” required to reach pre-defined zero energy performance for a specific climate and building typology. It describes a general methodology based on fundamental principles of designing high performance buildings for comparing while building Net ZEB solution sets for cold, moderate and hot climates. The methodology constructs the solution sets in four steps by: selecting and characterising buildings according to their type of use and regional climate conditions; identifying the combinations of compatible energy efficiency and energy supply measures applied to the selected buildings; assessing the delivered energy of the primary energy and the Net ZEB performance (balance); and delineating these solution sets according to the chosen type of building and climate conditions.

Chapter 3 displays the collected data from the thirty (30) case studies by listing the various measures undertaken to reach the zero-energy balance. It provides summary description of these measures presented in frequency histograms according to building type, design challenges, technology requirements and climate type. The intent is to document as much information as necessary to allow informed determination of the kind of measures that can be adopted to enable buildings (residential and non-residential) reach the net-zero energy targets in different climates.

Chapter 4 shifts the discussion towards design of Net ZEBs from an architectural perspective. It complements the energy-focused analysis undertaken in the accompanying chapters to integrate the ideas that architects consider when design these buildings. In this context discussions on building design are extended to include the impact of Net ZEBs on the surrounding landscape.

Chapter 5 introduces the monitoring of Net ZEBs and a discussion on post occupancy behavior. It is one thing to design a Net ZEB, but unless it is monitored for its performance in real-life situations it may not meet its design objectives. In this chapter the issue of comfort is presented from the points of views of building managers and occupants along with the energy performance of the 30 case studies. Descriptions of two protocols for monitoring building energy performance and indoor air quality are also provided, with a detailed discussion of the energy and IEQ monitoring systems at the EnerPos building on Reunion Island.

Chapter 6 examines the lessons learned based on feedback from the building designers, architects, engineers and Net ZEB occupants. It presents observations, anecdotes and experiences gathered from a series of selected face-to-face interviews with the design team and occupants of seven case study buildings and present some recommendations regarding future designs.

This book was written primarily by country experts participating in Subtask C of the IEA SHC Task40/EBC Annex 52. Subtask C, entitled Advanced Building Design, Technologies and Engineering was focused on: developing whole building net-zero energy solution sets for cold, moderate and hot climates with exemplary architecture that would be the basis for national demonstration projects; documenting Net ZEB design options in terms of market application; and developing guidelines and tools for industry adoption of integrated designs and concepts. Subtask C participants settled on carefully selected 30 high quality Net ZEB case studies to form a greater understanding of practical and technical challenges on building Net ZEBs. Members of Subtask C were a diverse group of researchers from universities, national research centers, and the building industry.

Readers are encouraged to explore the products of the five-years of in-depth studies by the 82 IEA SHC Task/EBC Annex researchers world-wide on the Web site


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