1
Introduction

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...