Design Your Own Adventure: Combining Energy and Cost Analysis with
Revit
Introduction
Design can be like a ‘Choose Your Own Adventure’ book. Wouldn’t it be nice to flip to the ending instead
of heading out on a long design detour? When it comes to making sustainable design decisions, the
earlier they are made, the better. Good decisions are informed by good questions and the information
they produce. Along with best practices, we need to be armed with accurate data about the building;
price, energy usage, appearance etc. One way we can get this information is by using Revit Architecture
2011 along with programs like the IES VE Toolkit and SmartBIM QTO. We will examine a scenario where
the designer and client are trying to understand the implications of design decisions on price, LEED
credits including the LEED Daylight credit, and overall energy usage.
It should be said that these tools do not turn architects into energy and cost consultants. We are using
this software understand relative differences and improve the design. The consultants can pick up
where we leave off and do what they do best. They may even be able to use our energy model.
Because we’re not trying to be energy or cost consultants we want to use tools that are easy, reliable
and inexpensive. Before we get into the story of the example project let’s take a quick look at the tools
we will be using.
The Tools
Revit Architecture 2011
The enhancements to Revit Architecture 2011 reveal Autodesk’s intent of integrating analysis tools
within the product. The Sun Path Interactive tool for visualizing the impact of natural light and shadows
on buildings and sites is a great starting point in examining the site. Display performance improvements
(over 30%) help to make this interactive sun/shadow tool truly ‘interactive’. Additionally, Revit 2011 will
now maintain a high level of geometric accuracy for elements placed within 20 miles of the project
origin. Of course, we can’t underestimate the value of a Revit 3D model. We want to see problems
early, avoiding waste. We want the client to be happy with the look and feel of the building inside and
out. Renderings, 3D Sections and schedules are powerful tools in the sustainable and LEED process.
Plug-in Play: IES Virtual Environment, SmartBIM QTO
A Plug-in is software that can take the building information model to another level. We will look at two
such plug-ins, IES Virtual Environment and SmartBIM Library. Both plug-ins install into the Add-Ins Tab of
the Ribbon. Having them inside of Revit makes them easy to access and use, eliminating the frustrations
of exporting and importing from one program to another.
IES Virtual Environment
The IES Virtual Environment software is well respected for energy analysis and used by engineers
worldwide. IES discovered that architects would also like to use their tools. So, they built a starter
version which plugs in to Revit called IES VE Toolkit. There is also a direct link from Revit to the full
Virtual Environment. The IES VE Toolkit will convert your model into gbXML and use it directly in the
same session of Revit. You will then be able to define characteristics about the site and building
construction. Then you can choose from a variety of analysis options. To get the HTML analysis reports
you simply need to press the right button. Some of these inlcude ASHRAE/CIBSE heating & cooling loads,
water use, comfort and the 2030 challenge. We will be using primarily the Energy/Carbon Simulation in
which we can interrogate a range of energy and carbon metrics (without shading, with simple external
shading, or with advanced solar penetration – using a dynamic thermal simulation at sub-hourly timesteps).
We will also use the Daylighting button which Covers LEED Credit EQ8.1. We have the ability to define
what spaces are included in the analysis. Output includes indicative pass/fail result, previous run
comparison, visual floor-by-floor movie and tabular results to enable easy identification of marginal fail
rooms. The file that you create for the IES VE Toolkit can be passed right into the full IES Virtual
Environment Software for CFD, lighting analysis and other in-depth calculations.
Note: It should be mentioned that the Green Building Studio web service is now included with
Subscription to Revit. This provides a high level report on energy cost and alternatives, the LEED
Daylighting credit, water and more. While this is a great tool for general information there is no
opportunity to expand the analysis as you can with the IES VE products.
SmartBIM QTO
SmartBIM QTO installs into the Add-Ins Tab of the Ribbon too. SmartBIM QTO matches the RS Means
construction database prices with your model and provides a building estimate. You can refine your
analysis by changing material and labour prices of each item and category. You can also export results to
Microsoft Excel and bill of material (BOM) files.
The Example Project
The designer is spending a day exploring early design directions. The project is a small restaurant, cafe
and wine bar located in downtown Toronto, Ontario. The client wants a modern, minimalistic style to
which they have provided photos of desired features. Natural lighting is highly desired. Exterior summer
patios need to be strategically placed for an enjoyable customer experience. The client is interested in
exploring LEED certification up to Silver. There is an ugly and busy parking lot to the south of the site
that the client wants to keep out of customer view. Don’t forget the tight budget and accelerated
schedule which always comes standard.
Examine the site
It has been said that an energy efficient building in Phoenix is not an energy efficient building in
Montreal. The local climate and situation of the site should drive your design. So, we will start our
design by picking the location on the Google Map built into Revit Architecture 2011. Massing Tools,
Sketchup or even AutoCAD 3D can be used for contextual buildings. It may be a good idea to create this
in a separate file and link it into your designs for context as needed. Revit Architecture 2011 has a nice
tool to show the Sun (Earth) position. Use this to examine how adjacent building’s shadows affect the
building in question. Soil cut/fill volumes may assist in quantifying the material that needs to be
removed or added to the site.
Insert Figure 1: JP Figure 01.png (Caption: The new Solar Path feature)
IES is ideal for displaying site specific climate and weather data. You may want to use IES Virtual
Environment to display a Wind Rose which will graphically show wind data during specific time periods.
The IES VE Toolkit can be used to instantly discover sustainable opportunities. In the case of this site
there is an opportunity to get 67% of annual electricity form solar panels and 58% of your annual water
load from rain. You can incorporate these possibilities right into your design even before schematic. It’s
not fun designing a rain water collection system after the building design is done.
Insert Figure 2: JP Figure 02.png (Caption: Wind Rose report from IES <VE>)
Make the Model
There are many good whitepapers and tutorials on how to properly model a building for energy analysis.
In fact the winter Issue of AUGI | AEC EDGE gave us some best practices in the article entitled “How to
Help Simplify Sustainable Design Analysis with BIM” written by Philip Membreno. Some suggestions are
to make a simple model, turn on Area and Volume computations and make sure your rooms extend
from floor to floor or roof face.
You will need at least one model for each major design iteration. Once you model your baseline design
do a simple ‘save as’ for more versions. Stay away from the Design Options and Phasing tools if possible
because this tends to create ‘issues’ in energy analysis as well as cost analysis.
The Import Model button on the IES plug-in menu allows you to pick a building type, location, heating
and cooling system and construction materials which represent a good baseline for the building.
Use the Energy/Carbon Simulation to get a projected annual energy usage. This will be calculated in
Mega Watt hours. This is broken down further by room, system (lights, boilers) and month.
The LEED Daylighting credit is just a single button click on the LEED menu in the IES VE Toolkit.
Calculating the LEED Daylighting credit for a building of this size may take as much as 45min.
When doing the cost estimate in SmartBIM QTO you will want to have only the model in the file, no
other buildings etc. When you run the initial takeoff SmartBIM will count all of your objects in your
model and provide you with a report. You can go through this report and confirm or change items that
you disagree with. When you run the actual estimate, SmartBIM will connect with RS Means
construction pricing database to match market material and labour prices with your Revit objects. The
actual report is generated in seconds. Any extra time you spend would be on refining the line items.
With some refinement it is possible to be within 15% accuracy of a conventional cost estimate.
So let’s run these tests on four models and see what trends stand out.
Choose your Adventure
Adventure 1 – Baseline (918 m2, see Figure 3)
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Projected Cost Estimate: 1,135,000
Projected Annual Energy Usage: 233 mWh
LEED Day Lighting Credit: 23%
Insert Figure 3 - JP Figure 03.jpg (Caption: Adventure 1 - Baseline information)
Adventure 2 – Clerestory Roofs, Reduced Balconies (918 m2)
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Projected Cost Estimate: 1,141,000
Projected Annual Energy Usage: 235 mWh
LEED Day Lighting Credit: 44%
Adventure 3 – Rotated Baseline Plan (918 m2)
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Projected Cost Estimate: 1,135,000
Projected Annual Energy Usage: 220 mWh
LEED Day Lighting Credit: 23%
Adventure 4 – Rotated Plan, Reduced Balconies (918 m2, see Figure 4)
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Projected Cost Estimate: 1,136,000
Projected Annual Energy Usage: 221 mWh
LEED Day Lighting Credit: 69%
Insert Figure 4 - JP Figure 04.jpg (Caption: Adventure 4 - Baseline information)
Remember, we are looking for trends. From Adventure 1 to adventure 2 we can see that all numbers are
rising. This is good when it comes to the LEED Daylighting credit but we are sacrificing both price and
overall energy usage to get there. Adventure 3, which is just the baseline plan rotated 90 degrees, is
better for the energy number but not for Daylighting. When we look at the difference between
Adventure 1 and 4 (see Figures 3 & 4) we can see the LEED Daylighting Credit factor is rising dramatically
while the energy usage is dropping. Also, the price of Adventure 4 has risen but not as drastically as
Adventure 2. Why don’t we go with Adventure 4 as our direction? Before we move on let’s talk a little
about the price. If the price seems too low it’s because it is. We have only walls, floors and roofs made in
Revit. If we had more modelled then the price would reflect that. For now this simplicity is a good thing.
Refine your Adventure
Now that we have a direction, let’s do some further analysis. We can start to look a little closer at the
site. For instance, we might now be concerned about the wind on the patios. This is where we could
again use IES Virtual Environment for wind data. Our Wind Rose could be specific to only the months or
even days in which the patios may be in use. Wind from neighbouring buildings can be studied if this is
warranted.
Since our client is concerned with getting natural daylight we may want to use IES Virtual Environment
Radiance tool to perform detailed daylight (see Figure 5) and glare (see Figure 6) studies.
Insert Figure 5 - JP Figure 05.png (Caption: Light penetration results)
Insert Figure 6 - JP Figure 06.png (Caption: Window glare results)
We can also push our IES VE Toolkit a little harder. Let’s study the envelope by choosing different roof
and glass materials. You have the ability to quickly swap out a material of one U/R value for another.
This will have a direct bearing on the Energy/Carbon Simulation. We can see and measure which
changes will provide the highest gains. Not all possible building material configurations are listed so it
may be better to focus on the U or R value.
Adventure 4 Envelope Study - Baseline
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Roofs: Concrete with 4” Insulation
Glass: Low-E Double Glazing
Projected Annual Energy Usage: 221 mWh
Adventure 4 Envelope Study - Roofs
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Roofs: Concrete with 9” Insulation
Glass: Low-E Double Glazing
Projected Annual Energy Usage: 215 mWh
Adventure 4 Envelope Study - Glass
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Roofs: Concrete with 9” Insulation
Glass: Low-E Triple Glazing
Projected Annual Energy Usage: 206 mWh
This study shows us the effect of changing materials. IES Virtual Environment has the ability to change
each layer of the wall and see the accumulative U or R value. In some cases it may surprise us to find
what changes have the biggest impact. It may mean spending more money on insulation instead of
external sun shades or vice versa.
We may want to try to adjust the price to the new materials. You could do this by updating the line
items in SmartBIM. This may take a little research on your part. How much more does 9” insulation cost
vs. 4” insulation, is it even available? You may not decide to go with the exact material configuration but
a similar U or R value. This can take some research to find out the insulation values of certain materials.
Now that you have the energy model and the cost estimate it is easier to engage with a consultant and
provide them with some advance information. IES North America Consultancy can take your energy
model to the next level and then show you how they did it.
http://www.iesve.com/ConsultancyNAmerica/
Design Adventure Summary: All in a day’s work...
What did we learn by doing these studies:
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LEED Daylighting Credit of 69% is 42% better than baseline and 6% off target
Projected Energy Usage of 206 mWh per m2 is 13% better than baseline
Envelope study reveals that the roof and glazing materials have a noticeable effect on the energy usage
Initial Cost Estimate reveals a price increase of 11% over baseline
Lighting study reveals high glare on the top level: colours and summer shades considered
Wind study confirms balcony placements and wind screens.
67% of annual electricity is possible from solar. Examine possible locations for these.
Rain may provide 58% of annual water load
Our goal was to take a direction which agrees with the client requirements. This is not always easy as
some requirements contradict each other. This may mean making some tough decisions early on. But
early decisions always cost less. It’s important to look for trends in our studies. We may even find some
things that we weren’t expecting. All of this has to be done quickly and be cost effective. In the end we
are looking to create a beautiful, sustainable and affordable building for our clients. This means making
the most of our experience and the tools available. So go ahead, flip to the end of the book and design
your own adventure.