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
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
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
The results of energy performance simulations can be used
- 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
- 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.
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.
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.
- EnergyPro, another DOE-2 based building energy
simulation program. It is developed and supported by
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.
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
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.
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.
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.
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
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
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.
|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
California Leading the Charge in Sustainable Building and
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
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.
Several utilities are offering upcoming training on the EnergyPro
software as it pertains to Title 24 Energy Code compliance
How to Think About Building Energy Models for
- In Irwindale: Introduction for Nonresidential, March 31, 2009.
- In San Diego: Introduction for Residential, March 24, 2009. See
- 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
More info >.
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
an online resource center for information on energy efficiency design practices in
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.