Using Energy Analysis Tools Early in the Design Process to Achieve Big Reductions in Building Energy Consumption

Energy and climate change challenges are driving more building owners and design teams of new commercial construction in California to explore ways to create very low-energy buildings. Meeting the energy use goals defined by Title 24 or groups such as Architecture 2030 will require bold steps from building owners and revolutionary thinking from design teams (see e-News #62). Such teams will not be able to achieve these ambitious goals if they think of energy efficiency as an add-on to be addressed down the road, after crucial decisions about the building's design have already been made.

How can architects and engineers get a handle on energy consumption at the very beginning phase of design?

• The greatest benefit of energy analysis occurs when simulations are conducted early in the design process. With early analysis, the energy implications of various design alternatives can be evaluated before crucial design decisions, such as window-to-wall ratios or building massing, are set in stone.
• Energy analysis tools can point engineers and designers toward the most efficient and effective energy-saving strategies.
• Multiple building designs, incorporating a wide range of strategies, can be modeled and analyzed simultaneously, comparing the annual energy consumption of each design.

The range of analysis tools now available is greater than ever, with each offering different capabilities. In this issue of e-News, we look at the various tools and their relative advantages and disadvantages.

When to Perform Energy Analysis Energy analysis can be used early in the design of a project, to help calculate loads, resolve solar geometry or wind issues, identify climate-specific "free energy" opportunities, such as thermal mass or evaporative cooling, and generally optimize the energy performance of a project. In later stages of a project, modeling software can help to choose among several design strategies or specific projects. Finally, such software can establish compliance with applicable codes and standards when a project nears completion.

Why Use Energy Analysis Tools?

Some architects use simulation tools to perform basic energy analyses "in-house," but most rely on consultants for this work because of the time and expense required to build up the expertise required for complex analyses. Even if you don't do the energy performance simulation yourself, it's helpful to know the capabilities of these programs so that you can effectively work with an energy modeling consultant to get useful results as early as possible, and make the most of those results throughout the design process.

The results of energy performance simulations can be used to:

• Get a handle on the most cost-effective and practical design options early in the design process.
• Identify integrated design benefits, such as HVAC system downsizing due to solar control and daylighting strategies.
• Calculate energy performance for compliance with codes and standards, such as Title 24, or for achieving Leadership in Energy and Environmental Design (LEED®) Energy & Atmosphere credits.
• Maximize Savings By Design incentives by choosing cost-effective, energy-efficient alternatives.

A Closer Look at a Handful of Tools

U.S. DOE's website, Building Energy Software Tools Directory, lists 335 building software tools for evaluating energy efficiency, renewable energy, and sustainability in buildings. Here's an overview of a few tools that designers of commercial buildings in California may find particularly useful. Energy Design Resources offers eQUEST as freeware, but does not endorse particular products and encourages you to explore the DOE website for excellent synopses of many more programs.

Website: apps1.eere.energy.gov/buildings/tools_directory/

DOE-2 Energy Simulation Software is currently the most widely used building energy simulation code. The DOE-2 code was developed by Lawrence Berkeley National Laboratory (LBNL) with funding provided by the U.S. Department of Energy. DOE-2 makes up the underlying simulation engine for several of the most popular building energy simulation tools in use today.
Website: simulationresearch.lbl.gov

Among the simulation programs based on DOE-2 are:

• eQUEST, a no-cost whole-building energy simulation tool, is developed and supported as a part of the Energy Design Resources Program. Website: www.doe2.com/equest. You can also download a copy from EDR's Software Tools directory.
• VisualDOE, a whole-building energy simulation tool similar to eQUEST. It also uses the DOE-2 simulation engine, and is developed and supported by Architectural Energy Corporation.
  Website: www.archenergy.com/products/visualdoe/
• EnergyPro, another DOE-2 based building energy simulation program. It is developed and supported by EnergySoft.
  Website: www.energysoft.com
  

Making Sense of the Simulation Results User-friendly energy analysis tools such as eQUEST allow you to view simulation results in graphical formats, such as graphs of estimated overall building energy on an annual or monthly basis, and comparison of performance of alternative building designs. Simulation results can be broken down by energy end-use (as shown on right), allowing the user to identify the most practical and effective energy-saving strategies.   Source: eQuest

EnergyPlus is considered to be the next step for building energy modeling software, and is seen as an eventual replacement for DOE-2 based software. One of the advantages of EnergyPlus is its modularity. This allows for modeling of HVAC controls and more accurate modeling capabilities for highly specialized systems, such as solar thermal collectors, thermal mass elements, and refrigeration.. The main disadvantage of Energy Plus, at this time, is the lack of an easy-to-use graphical user interface (GUI), along the lines of existing DOE-2 front-end programs.
Website: www.eere.energy.gov/buildings/energyplus

IES Virtual Environment is a suite of energy simulation tools developed by UK-based company Integrated Environmental Solutions. The software allows for the creation of a single model and, with the assistance of various toolkits, the evaluation of a number of complex building performance criteria. The software suite includes toolkits for energy, lighting and daylighting, computational fluid dynamics (CFD), costing, and solar geometry, among others. There is also a direct link between IES Virtual Environment and Autodesk's Revit Architecture and MEP software. However, partially due to the fact that the software originated in the UK, some of the interface for compliance with US-based standards needs to be improved.
Website: www.iesve.com

Ecotect is a building simulation software tool created primarily for architects. While its whole-building energy simulation capabilities are less robust than either Energy Plus or DOE-2, Ecotect includes features for modeling shading designs, daylighting, thermal loads, and more. One of the particularly useful tools for the early phases of building design is the Weather Tool, which helps the user identify which building energy strategies may be most applicable in a particular climate.
Website: www.ecotect.com

Green Building Studio is an online-based software tool that allows building designers and engineers to make informed decisions about the energy impacts of certain building energy systems. The software also supports carbon footprint and other environmental calculations. Green Building Studio's web interface connects with Autodesk's Revit Architecture and MEP software, facilitating an integrated design approach.
Website: www.autodesk.com/greenbuildingstudio

CFD Simulation allows the user to analyze the energy impacts of airflow patterns, both internal and external to the building. Of particular interest to building designers is the analysis of interior ventilation patterns, such as for natural ventilation, displacement ventilation, chilled beams, and other non-conventional systems. Exterior analyses can provide helpful information on landscape design and building orientation for the purpose of mitigating cold, winter winds, or effectively channeling summer breezes for natural ventilation. Many commercial CFD packages are available, including Fluent, Phoenics, and Flow3D, among others.

Daylighting simulation is an effective way to optimize the light quality of interior spaces and to reduce the amount of energy used to supply that light. Daylighting software can predict interior light levels at any hour of the year, and can help to determine the most effective window sizes and locations, or the best interior layout and surface finishes. Additional software tools may be used to optimally locate photosensors or design shading devices. Commonly-used daylighting tools include Radiance, DAYSIM, AGi32, and SPOT.

Life Cycle Assessment (LCA) is the systematic evaluation of all materials and processes applied throughout the life cycle of a building, in order to determine and reduce its overall environmental impact. LCA examines the extraction, transportation, refinement, and manufacturing of raw materials, as well as building construction, operation, maintenance, and eventual demolition. While it can be extremely difficult to conduct a proper Life Cycle Assessment from scratch, several LCA tools are available to facilitate the process. One building-specific LCA package is the Athena Environmental Impact Estimator. Other, more elemental LCA packages include SimaPro, BEES, and others.

Training Highlights

California utilities offer outstanding educational opportunities that focus on the design, construction and operation of energy-efficient buildings. Listed here are a few of the many upcoming classes and events; for complete schedules, visit each utility's website. California Leading the Charge in Sustainable Building and Resource Conservation* State rebates, marketing support, incentives and support from local utilities and even new financing packages offer builders exceptional benefits for making sustainability a priority. A panel of experts who have embraced sustainable building will show architects, builders, and industry decision-makers how best to get started and put these programs to work. Offered March 4, 2009 in Irwindale. See website. Benchmark Your Building Now Benchmark your building during this workshop using ENERGY STAR Portfolio Manager's account set-up and the activation of PG&E's Automated Benchmarking Service. Offered in San Francisco on March 5, 2009 and March 6, 2009. See website eQUEST Software Training: Intermediate This intermediate training covers eQUEST's detailed interface and use of the software to produce DOE 2.2 hourly energy reports. It will also describe how to model more complex HVAC systems and energy efficiency measures such as daylighting. Offered in San Francisco on March 12, 2009. See website.

EnergyPro Software Several utilities are offering upcoming training on the EnergyPro software as it pertains to Title 24 Energy Code compliance documentation. In Irwindale: Introduction for Nonresidential, March 31, 2009. See website. In San Diego: Introduction for Residential, March 24, 2009. See website. In San Francisco: Advanced Energy Pro for Nonresidential, March 10, 2009. See website. In Sacramento: Introduction for Residential, March 17, 2009; Introduction for Nonresidential, March 18, 2009; Advanced for Residential, April 21, 2009; and Advanced for Nonresidential, April 22, 2009. More info >. How to Think About Building Energy Models for Nonresidential Buildings Learn the capabilities and limitations of energy models and how to improve architect-engineer communication to effectively use energy modeling throughout the design process. Offered May 6, 2009 in San Francisco. See website.

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e-News is published by Energy Design Resources (www.energydesignresources.com), an online resource center for information on energy efficiency design practices in California.

Savings By Design (www.savingsbydesign.com) offers design assistance and incentives to design teams and building owners in California to encourage high-performance nonresidential building design and construction.

Energy Design Resources and Savings By Design are funded by California utility customers and administered by Pacific Gas and Electric Company, Sacramento Municipal Utility District, San Diego Gas and Electric, Southern California Edison and Southern California Gas Company, under the auspices of the California Public Utilities Commission.