Energy Modeling in Architectural Design

Timothy Hemsath, Kaveh Alagheh Bandhosseini

• Publisher: Routledge
• Year: 2017
• ISBN:
  9781317496335
• Edition: 1
• Topic: Architecture
• Subtopic: Architecture Methods & Materials

Energy Modeling in Architectural Design demonstrates how design elements can lead to energy savings, to help you reduce the energy footprint of your buildings. In addition to identifying climate opportunities, you'll also learn fundamental passive design elements for software-agnostic energy modeling of your projects from conception. Using parametric models and testing each element during design will lead you to create beautiful and high-performance buildings. Illustrated with more than 100 color images, this book also includes a pattern guide for high-performance buildings, discusses energy and daylighting optimization, and has a glossary for easy reference.

1
Introduction

In an era of climate uncertainty and pressures to reduce carbon emissions, buildings hold the largest share of energy consumption and are therefore a significant contributor of carbon into our atmosphere. We know that buildings consume energy and that conserving energy by operating a building intelligently is important. Since the primary energy source for a building is the power plant, we need to be conscientious in the use of this energy. Carbon limits on coal-fired plants place increased pressure on the use of energy in both new and existing buildings.

According to the Intergovernmental Panel on Climate Change (IPCC), buildings offer the lowest-cost investment potential for reducing greenhouse gases (GHGs) from carbon emissions. This cost capacity is twice that of any other category, with the second being industry. It helps to know that the decisions we make about a building’s design early in the process actually reduce energy consumption and climate emissions—in fact, the IPCC estimates that in the building sector, recent advances in technologies, know-how, and policies provide opportunities to stabilize or reduce global energy use to about current levels by mid-century.¹ In the long term, saving energy and reducing GHGs helps save building owners and operators money and prevents wasteful energy use during operation. Energy modeling allows one to demonstrate in measurable terms the energy savings of a building’s design from the very conceptualization of a project.

Fundamental decisions made by designers, architects, and engineers early in the design process represent some of the most cost efficient ones. For instance, a building’s shape and orientation are decisions made with minimal project cost implications. The building blocks we begin with in design (see Figure 1.1) are essential to conserve energy and use it efficiently. This book puts measurable energy consumption numbers to a few of these design tenets, showing how impactful they are for early design decisions. We can make wiser and more energy-efficient decisions about our building design when considering energy and following a design process that incorporates building energy modeling (BEM) to simulate a building’s operational energy use.

There are endless potential building sizes, shapes, and forms—not to mention a wide range of functions and uses—from those with high energy use to low energy use, making it quite a challenge to piece together the range of possibilities. BEM tools employed in architectural design help harmonize them. Using these tools early and often provides the potential to continuously track and benchmark performance against the design goals a team might have for a project. As the building evolves, the specificity of BEM closes in on a more accurate prediction of energy use. A design might start as something simple and evolve into a complex building; using BEM along the way allows us to understand its energy performance from start to finish.

One key to a successful architectural practice today is how to use BEM in the building design process. Using energy modeling is essential to making early fundamental decisions about energy. However, anyone who has attempted to learn the energy modeling process can tell you how overwhelming it can be. There are innumerable barriers to overcome: What software do I use? When should I use it? How does it work? What am I using it for? This book will answer these questions and review in a non-specific software format how to use the tools available, when to use them, and what to do with the outputs to help in the design.

Within the energy modeling field there is an increasing number of BEM professionals certified by a consortium of professional organizations. This expertise will help provide knowledge experts to transform this industry in the next decade. However, not every professional wants to specialize in BEM. If you want to design buildings and incorporate the most energy-conscious methods into the design without becoming a BEM expert, then this book is for you—yes, you—the architect who wants to make smart decisions about energy in buildings.

This book seeks to inject BEM into architectural design, helping students and professionals to understand the workflow, leverage it to make decisions, and ultimately reduce the energy footprint of their building designs. The energy modeling process is not unlike the one we use to design: You start with some basic information and a few assumptions and go. However, the difference with BEM is the amount of upfront input required to run a simulation. What energy modeling software requires one to know in advance of producing results is challenging and can hamper the productivity of the design process. In this book we will show how to combine these workflows and leverage them in concert with design to make smarter decisions about a building’s performance.

As part of designing to reduce energy consumption, what the reader can take away from this book is a framework for making productive energy-saving choices during building design. Specifically, this book discusses four key concepts that designers should incorporate in their practice, and students use in their design studios. First, a fundamental review of energy efficiency and climate helps demonstrate how design elements inform energy-saving architectural design practice. We review a range of design elements common in building design for a variety of climate zones. Second, we discuss fundamental elements critical to the energy-efficient design of buildings. Using BEM, we show how these elements have the potential to reduce a building’s energy consumption. Third, we review how to create computationally based parametric models and means of testing and optimizing each element with energy modeling during design. Finally, from these results we provide an energy pattern guide for a range of building sizes.

Inspired by Victor Olgyay’s 1963 book Design for Climate, this book looks to advance the body of knowledge about passive solar bioclimatic design by using BEM and parametric modeling. The foundation for this book respects the historic research about bioclimatic design and passive solar architectural strategies. While Olgyay’s book focused on residential architecture, the ideas he expressed have been used and explored across the entire discipline. Olgyay quantified the energy implications of design decisions four years before the invention of the modern calculator. We hope the ideas in this book hold equal relevance for advancing architectural design into the future.

Figure 1.1 Energy pyramid showing design decisions to maximize architecture’s role in reducing our reliance on energy based upon building type and climate to minimize the need to use power, using energy efficiently, and producing energy.

Now emerging is a disciplinary field somewhere between traditional architectural design and engineering for high-performance buildings. What it is called has yet to be determined, though we’ve seen, read, and heard it referred to as design performance analysis, conceptual energy modeling, building performance modeling, or simply building energy modeling. While energy modeling has over the years situated itself primarily within the engineering field, this new use doesn’t sit comfortably within the traditional engineering discipline. Architectural offices are doing their own simulations, creating energy models, and hiring consultants to supplement their designs with energy modeling analysis. Therefore, the space to define the methods, timing, sequencing, and operational application of building energy modeling within design is wide open.

The book’s focus is on the bottom of this energy pyramid, those measures that minimize our use of energy or power within the building. Illustrated in Figure 1.1, our energy pyramid for building design is partially derived from presentations by Peter L. Pfeiffer, FAIA, and Norbert Lechner. Both Pfeiffer and Lechner speak in their own ways about maximizing architecture’s specific role in reducing our reliance on energy. As such, the discussion on BEM in design purposely omits discussing the role of active building elements in using energy efficiently. These elements include the mechanical and electrical systems, controls, equipment, appliances, and fixtures incorporated into a building. This book focuses on the passive aspects of design.

Why write this book now? The conditions are right for a book that highlights how advances in computation in architectural design have enabled quicker and greater amounts of design feedback. The challenge of having more information lies in what to do with it. Computing power enables all architects and students to produce results using BEM without leaving their desks. Therefore, we ask, to what end? And for what purpose?

Design Process

Not all BEM tools available for architectural design are created equal. Parsing these programs to help differentiate the software is about finding those tools suitable for architects. The American Institute of Architect’s (AIA), An Architect’s Guide to Integrating Energy Modeling into the Design Process,² along with other published guides from the Rocky Mountain Institute (RMI),³ the U.S. Department of Energy (DOE),⁴ and software vendors themselves highlight the comparative pros and cons of the various BEM tools. Finding the right tool for the job is dependent on a range of items related to how you design, how your company does business, and the questions you seek to answer. In the examples highlighted in this book, we use several different BEM tools to demonstrate how using BEM for architectural design benefits decision making.

Out of the plentiful supply of energy modeling software options available—formerly highlighted by the DOE and now by the International Building Performance Simulation Association (IBPSA)⁵—few programs are specific to architectural design. Before choosing a BEM tool it is important to evaluate many of its key features to understand what it will tell you, the interoperability of the software related to your design software, what the software uses as a simulation engine (or calculation cruncher), outputs, user interface, and other specific needs you may have. The tools ultimately need to fit how you design.⁶ There is a learning curve to picking up BEM for design, and part of that curve is knowing when and for what purpose BEM can be used.

In a few cases, using BEM for early-stage design decision making, known as design performance modeling (DPM) or building performance assessment (BPA), is helpful to frame this activity. DPM as defined by the AIA, and BPA by Autodesk, is an early-stage model that focuses on various aspects of building design, giving value to and measuring the energy impacts of design decisions. Both are methods for modeling a building’s energy performance during design to understand design impact. Since DPM and BPA relate to design decisions and rely on BEM to provide the metrics and measurements, we assume all discussions that follow pertain to modeling design performance for analysis or assessment, and are referred to as BEM.

Early in the design process, BEM is not about compliance or prediction but about comparison: Evaluating the impact that different design decisions might have. Comparisons about different designs, systems, materials, and envelopes spell out different ways buildings could achieve better performance and be more energy efficient. Since there is not necessarily one way that designers could benefit by using BEM early in the design process, we instead propose a cornucopia of options throughout this book. Not all practicing architects fully understand the benefits of BEM to their process, but they see energy modeling as providing answers to common hurdles they encounter. Since knowledge is power, it is helpful to know, for example, what glass types may be ideal for a given situation, but this and other specific items are highly interrelated to many other early design decisions. Specifically, changes in the building geometry will modify the whole building’s behavior, shifting its interior climate and ideal material properties. Therefore, there is no ideal answer to determining the building’s optimal performance properties, but the solution will continually shift along with the design.

Along these lines, it is key to use BEM to evaluate the right information at the right time. Since there are many complex decisions made about a building’s design throughout the design process, we have attempted to provide a framework to help identify what information can be evaluated when in design and in what way this knowledge can aid the design process.

The impetus for the proliferated use of BEM that motivates this focus is to make our built environment more energy efficient, therefore reducing carbon emissions. No two buildings are the same, and what might work well in one climate does not transfer to others. Using BEM enables designers to make better decisions to aid in saving energy and money.

Financial Benefits

There is a business case for the use of BEM in architectural design. There are three different financial areas where savings can occur for existing building owners and operators, making buildings more resilient in terms of fuel source availability, and making affordable housing more affordable.

BEM can reduce operational expenses related to the energy consumption of buildings, helping to save money for future and current building owners. Using BEM helps identify energy conservation measures (ECMs), along with proper HVAC system sizing for a given project. It is possible to reduce the initial costs of the HVAC system in addition to the long-term costs associated with operating it. Another benefit could include the greater appraisal value of the overall building. Since incorporating daylighting and other energy-saving elements improves the overall building quality, owners can potentially expect a higher resale value. Also, depending on the design, there could be potential increases in employee productivity, retention, and the overall health aspects associated with high-performance buildings.

Energy efficiency can create a building that has the potential to be resilient to future economic shifts, in addition to fuel source uncertainty. As we review in Chapter 2, society’s views on energy do change, and the resources we rely on are not entirely stable over the long term. While we often react to a sign that comes too late, proactive planning realizes that nothing is necessarily stable and that a more resilient system accounts for a range of variability. A building that is more energy efficient will rely less on grid-tied energy, and adding renewable energy will further improve a building’s resilience.

In residential markets, where the costs associated with utility bills are significant, it is perhaps more helpful to provide resilience in affordable housing. The RMI has identified that affordable housing often has unaffordable energy costs,⁷ and energy efficiency can help by potentially reducing those energy costs by 90 percent. This requires a whole-building approach to evaluating the many different conservation measures made possible with BEM.

Architectural Relevance for Professional Readers

The AIA reported progress toward the 2015 goal of reaching 60 percent greenhouse gas (GHG) reductions as part of the 2030 commitment, and in 2013 66 percent of the total gross square feet were built used energy modeling, leaving 34 percent of the buildings constru...