U.S. Department of Energy - Energy Efficiency and Renewable Energy

Building Technologies Office

Going With the Flow: Designing High-Performance Buildings With EnergyPlus (text version)

Below is the text version of the Webinar titled "Going With the Flow: Designing High-Performance Buildings With EnergyPlus," originally presented on February 16, 2010. In addition to this text version of the audio, you can access a PDF of the slides (PDF 3.6 MB) and a recording of the Webinar (WMV 11.5 MB). Download Adobe Reader.

Operator:
Good morning and thank you all for standing by. At this time, all participants are in a listen-only mode. After the presentation, you will conduct a question-and-answer session through your net portion today. Today's conference is being recorded. If you have any objections, you may disconnect at this time. I'll now turn the meeting over to Mr. Anthony Perkins and we may begin.

Anthoney Perkins:
Thank you, Lou. My name is Anthony Perkins and I'd like to welcome you to the Webinar titled Going With the Flow: Designing High-Performance Buildings With EnergyPlus. This Webinar is presented by the Building Technologies Program at the U.S. Department of Energy. We're excited to have with us today Drury Crawley from the Building Technologies Program to talk about EnergyPlus, a powerful energy modeling tool. But before we get started, I have some housekeeping items to cover. First, I want to mention to everybody that you are in listen-only mode as you were just told. We will have a Q&A session at the end of this presentation. You can participate by submitting your questions electronically throughout the Webinar.

To submit a question, simply click on the Q&A link at the top of the bar of your screen. Type in the question in the box and click Ask. Please be sure to click Ask and not the symbol of the raised hand. Our speaker will address any additional questions as time allows after the presentation. Also, I want to point out on the screen the http://www.buildings.energy.gov/Webinars.html. On that Webpage is a link to see today's slides. Also, today's presentation is being recorded and a video of the presentation will be posted in the near future.

Finally, we have a few quick questions to ask before we get started to help us learn more about the audience and target our future presentation. We will start with two questions now, and then we'll also have two questions at the end of the presentation before we go into the Q&A session. Please click on your screen to indicate the appropriate response. The first question should be up now on your screen. Please review the question and answers and click the appropriate response.

The first one is: How many people at your site are participating in today's Webinar? Please vote now. We'll leave it open just for a moment more. Okay, we're about to close the question, so if you haven't voted please vote. And we're going to go on to the second question. The next question is looking for information about what best describes your organizations or affiliations. So we'll give you a few moments to look at those and vote. We're about to close the question, so if you haven't voted, please vote now. Okay, thank you so much for your participation in those questions.

And now, I'll introduce to you our speaker. Dr. Drury Crawley leads the Department of Energy's Commercial Building Initiative. The goal of the Commercial Building's work is to achieve cost-effective, net-zero energy commercial buildings by the year 2025. To reach this goal, the Commercial Building Initiative focuses on research, extensive industry partnership and tool development. One of the key tools used to improve the efficiency of buildings is EnergyPlus. Drury is responsible for the development of EnergyPlus, which won an R&D 100 Award in 2003.

Drury has 30 years of experience in building energy efficiency, renewable energy and sustainability. A registered architect, he recently completed his Ph.D. in Mechanical Engineering on the topic of building simulation as a policy tool, looking at the potential impacts of climate change on the built environment, at the University of Strathclyde in Glasgow, Scotland. Now, I'll turn it over to Dru.

Dr. Crawley:
Thanks, Anthony, and welcome this morning. I'm delighted to be here. I'd like to give you a quick introduction to EnergyPlus, what it can do, and what it's best used for. So I'll go ahead and start. EnergyPlus is a simulation tool, but I want to back up first and give you a little context in why building energy use is important. First, if you look in terms of the share of the U.S. energy use, buildings account for about 39 percent. That has been growing. Industry energy use has been continuing to decline as it gets more efficient, and transportation is growing but not at quite the rate of building.

In terms of residential versus commercial, the commercial sector has also been growing faster than the residential sector, as we put more equipment, more computers and just more energy-intensive processes into our building. As you can see on the chart there, cooking, computers, refrigeration, electronics, lots of things going on there just beyond lighting and cooling. And all of them are playing a role in what's going on in the building sector. If we look at how that building's energy share – as I said it's 18 percent of the U.S. energy, and that translates directly into 18 percent of greenhouse gas emissions. And if you look in terms of where that fits worldwide, our commercial buildings alone already emit as much as all of India combined.

If you look in terms of square footage in the growth that we're seeing there, we started in 2003 with about 72 billion square feet of floor space. We are estimating today, that we're about at 82 billion. But one of the things that goes on, it looks like we've just got 10 billion square feet of new buildings in the last seven years, which is, you know, 10 percent growth. But the reality is that we actually deconstruct and demolish a lot of buildings. In the next 20 years, we're expecting that we're going to be demolishing on the order of about 16 billion square feet or about 20 percent of our stock. Meaning that, of the stock that's here today, 66 billion of it will still be around in 2030. It's still a pretty substantial amount. If you look at total new additions, though, we're expected to add another 38 billion. So at the top 40/60 split, new versus old over the next 20 years.

If you look in terms of the electricity growth, though, it's commercial buildings. It's 60 percent of the projected load for the next 20 years and that's where it's growing. Residential is still a big factor, but it's still the largest. Expect to see some growth in transportation and industrials but not nearly the level of what we're seeing in the commercial sector. If we look in terms of emissions, of course, transportation also includes petroleum products, so we do have carbon dioxide emissions from that. But still, most of the growth of all the sectors is the commercial buildings.

If you look in terms of what we're doing at the department for the Net-Zero Energy Commercial Building Initiative, we're looking at various goals and where they are, and this will give you kind of a stair step of where they're moving. Today, we've got a goal of improving new buildings by 50 percent and existing buildings by 30 percent. And we believe we can do that cost effectively, working with various groups to do that. Senate proposals for specific reductions in greenhouse gases – the bills that have been on the hill for 2020; 17 percent by 2020 and that's a significant reduction of what has to be done. That's, essentially, like taking 15 billion of those square feet off line completely.

2025, we have our goal—our performance goal of net-zero energy is really an energy-efficiency goal and weaving the rest of the load with renewables. And our goal, we found that the crossover point at which it pays to do renewables rather than more efficiency is about 60 to 80 percent, on average 70 percent. And if you look on up to 2039, all new buildings are zero-energy buildings, and that comes from the Energy Independent Security Act from a couple of years ago. If you look on out to 2040, EISA says that we want to take half of the remaining stock to zero, and do all of the stock – all zero-energy buildings, all commercial buildings – by 2050. President Obama has set a target of 83 percent reduction in full – all U.S. greenhouse gases by 2050, all very ambitious goals but achievable with the right tools.  

So let's talk a little bit about EnergyPlus. EnergyPlus is a fully integrated building envelope, HVAC, water and renewable simulation program. Notice I didn't just say HVAC. It does include other things that you could measure the performance of: water use, renewables and other pieces. It is available for free at our Web site at DOE, EnergyPlus.gov. And download a copy today, if you're interested. Originally based on BLAST and DOE-2, DOE-2 was the department's energy simulation program, and BLAST was a program that came out through the Department of Defense.

They worked in parallel for many years; each had strengths and weaknesses. And we took the opportunity a number of years ago to rethink how we were doing that to be able to build more capability and to really expand that. EnergyPlus now exceeds both of those in many ways. Neither BLAST or DOE-2 could do anything with renewables or water for the most part. And the integration that is going on within the program is far beyond what they could do.

EnergyPlus is one of the most robust tools today. We did a survey and few years ago and wrote a report, which you could look at on our Web site. And you'll see that it is one of the leading tools in terms of the breadth, the capabilities and what's going on. It really allows users to look at integrated performance analysis of both existing buildings and new buildings, low energy, zero energy; looking at all the different pieces for both commercial and residential buildings, and also look at what the impacts of on-site energy, combined heating, cooling and power, renewable energy sources.

Now, EnergyPlus is a standalone engine. And with that being said, there are several interfaces available; actually, a number of interfaces available today from private sectors, developers. We also have what we call our example file generator, which is actually just a pretty straightforward, simple Web interface which allows you to get an EnergyPlus file pretty quickly without having to put in all the information.

We first launched EnergyPlus about nine years ago, and we update twice a year, April and October. As of this morning, we're about 105,000 copies downloaded to date. And we support Windows, Linux and Mac versions of the program. All the interfaces at this point, for the most part are for the Windows platform because it's still about 90 to 95 percent of the downloads for the use of it.

In terms of what we were doing with EnergyPlus, we spent a lot of time looking at design and how we were going to move that. We really wanted to be able to be flexible, both DOE-2 and BLAST had gotten inflexible, both difficult to update, very expensive to update. And even then, we weren't sure that we were going to be able to make some modifications. Lots of new, low-energy technology. This is our research in both residential and commercial low-energy buildings. We need to be able to support that and do this analysis. It also does some hourly calculations and many output methods. Not just energy, not just demand, but also water and emissions. So if you want to look at the carbon dioxide impact of the particular technology or see how it might fit into a scheme for reducing carbon, that's possible within EnergyPlus.

We focus very much on documentation. That was one of the key designs and key commitments we made early, is to have this as well documented as we could, and we continue to enhance that. We also do extensive testing and validation throughout development. But we know that all software has bugs, and we continue to fix those and are updating and trying to minimize that as we move forward. But if you want to see how EnergyPlus compares to other tools out there, there's our sort of testing suites for which we have results. And those testing reports are posted on our Web site.

One of the other things we do as a service to our users is provide as much weather data as we can because that's one of the key things people need to be able to do, is the local weather conditions for there. And currently, we have about 2,100 locations, worldwide, for that. We even have a Google Earth layer, and that's what the snapshot is if you want to look at it to see. So we've got a shot there, mostly of Asia. You can see all the locations primarily in China and India there.

And EnergyPlus has been used to work on a number of buildings. Our early days, the Freedom Tower, which is now known as World Trade Center I, EnergyPlus was being used to look at some of the options and how the energy efficiency was going on there. And the New York Times Building, recently completely, it was being used throughout design, even into operations to look at building energy simulation of potential alternatives, and also to look at controls, peak demand and energy-use impact.

A couple of other buildings: the San Francisco Federal Building, they used it – this building, the designers wanted to do a natural cross-ventilation system, very difficult to do in a lot of the simulation tools out there, but EnergyPlus could handle it. So they were able to reduce the amount of cooling required just to be able to meet severe conditions and be able to do that. There is mechanical – some mechanical cooling in the high-rise portion, but it substantially saved funding for this federal building. San Francisco Supercomputer Center, they also used it to do thermal simulation and natural displacement ventilation analysis, and even some climate analysis, so the impact's there.

So I want to talk a little bit simulation versus operation, and why they're different and why you really should expect them to be. I use this quote from Stewart Brand. He wrote a book called, How Buildings Learn. Stewart really tagged it as far as I was concerned with this statement: Every building has a forecast and every forecast is wrong. Because when we're designing a building, we're guessing. We really are. We don't know who's going to be in the building. Unless we've got a specific client that knows exactly what's going on in there, most of our buildings are designed to be generic and to support a certain level of occupancy and equipment. And we have to build in flexibility to do that. So when you're doing simulation, you're using professional judgment. But, realistically, it is just a guess, so you should expect that simulation, unless you have really good information, is going to be different from that.

Well, let's talk a little bit more about that. In our low-energy building research, we found that it's been critical, really, to help us design and operate the buildings and to support decision making throughout that process. Here's an example of one of the zero-energy buildings operating today: It's the Lewis Center at Oberlin on the College at Ohio. That building initially did not meet zero energy. They had to add more photovoltaics to be able to get it. But they were able to look at it and see how – what the additional amount they would need from not only the utility bills, but from the prediction that the simulation was – calibrate that simulation to actual operation.

This is talking about the other issue there. But the last one is GIGO, which is garbage in, garbage out. And I really just want to make that point. This statement, if you could have read it, says that buildings use more energy, typically, than simulations unless you really have good information about the building. They typically produce less power than you would predict. They're typically not as comfortable and the controls have problems. And it all comes down to that last piece, which is GIGO or garbage in, garbage out. The more information you have about the building and how it operates, the better your simulations are going to be.

So why would you use simulations? Lots of reasons. There are simulations that can start telling you what your options are and opportunities from the earliest phases of design. You can look at what floor plate we should be looking at. Where are the biggest opportunities?  How can we reduce that?  It also, we find, helps focus the design team or the energy retrofit team to really focus their energy to use reductions where they'll be most effective. You know the good model of the building that's calibrated to an existing building's utility bills, which is possible. Then you're able to look at what the opportunities are and how you could do that.

It also allows you to look at am I going to meet my targets?  Am I going to meet the benchmarks?  Am I going to comply with my standards or am I going to exceed those where we go for maybe a green-building rating, and what's possible there?  They also allow you to do sizing for the equipment. What should I look for to get enough power out of that photovoltaic system or enough energy and water out of the other renewable systems?  And it allows you to look at alternatives as you're starting the programming, on through construction, operations and into retrofit.

It's really – probably the strongest use for energy simulation has been for retrofit. We found that it's about half and half, new buildings versus retrofit. So that retrofit, you know what the energy footprint is and you know what the opportunities are, so you can start replacing equipment and see how that looks within the building. So, and lastly, it's cheaper than building something and finding out it was wrong. So it's easier to do a model of the building and to find out what the best combinations are that are going to give you the most savings if you're doing your new building or retrofit in this case.

So let's talk about using EnergyPlus in simulation and how it works because I want to show you some examples of that. EnergyPlus does – has an integrated simulation manager. It does a simultaneous solution for loads, system and plant, and it calculates what the conditions would be based on the climate, the indoor conditions, the equipment, moisture conditions in the building; after that, to a heating-and-cooling system to see whether it can meet that. And then that's finally passed to a plant. And if it can't meet the load then you're going to see that reflected in temperature change or humidity in the next. This provides really tight coupling between the air-and-water, basically, the system and plant side, and you get realistic simulation of capacity. So if your system's undersized, you really will see that and you'll see the zone temperature and humidity change.

EnergyPlus uses time-dependent conduction. We use – there are two ways you can do your – essentially, the heat transfer across the walls, windows, roofs, and floors with the conduction transfer functions or you could use a finite difference, which allows a lot more flexibility and variable property. So if you had a phase change material or something else, you could use that to do that.

EnergyPlus Version 4, our current version, released last October, some of the new features include an energy management system, which gives you a runtime language. So if you want to control things differently, then EnergyPlus would – and really emulate how an energy management system might, that's built into the tool now. There's a separate application guide, a new application guide that came out in October with that.

A couple of the others, we have AirflowNetwork, which allows you to do natural ventilation, and we added large horizontal openings which has been one of the things that a number of people have asking for, those natural ventilations. Also, moving on down to refrigeration, we have a strong work area with a number of grocery stores, and we needed to be able to accurately simulate what's going on in refrigeration. So we've been adding capability there to see secondary loop, walk-in refrigeration, all that in the last release. So if you are interested in other things that EnergyPlus has in it or what gets added every time, you can go to the Web site. Usually, it's a list of about 20 or 30 new features every six months.

So let's look at some of the interfaces. As you see, there is quite a long list. But, really, I want to draw your attention to two of them. On the kind of the center, on the left side, you see DesignBuilder. It's one of the full-featured ones, intended to be kind of a very robust tool. The other one, center top, is HEVACOMP. And both of those tools allow you to do full-energy simulation. Other tools kinda have different focuses and are working. So you see ENERGY-10, top left; the PV modeling within that tool was done by EnergyPlus. EP-Quick allows you to create an EnergyPlus input file pretty quickly. And it's freeware and there's links to this and all the programs on our Web site.

Two programs that focus on Windows fenestration is EFEN and COMFEN, and they, basically, allow you to default a lot of information about your building, and focus on the specific design aspects of the tool. ECOTECT's now owned by AutoDesk. It has been writing EnergyPlus files for a long time. So if you like the ECOTECT interface, it's a way to get geometry and some other information out into EnergyPlus. Another interesting one, the Hourly Load Calculation Program was developed for the Indian market where they needed a program to really look at what cooling loads would be and how they would just size those in a commercial building, so it uses EnergyPlus to do that. They're extending that to be a full interface to support the particular work there.

The other ones, there's actually several Chinese interfaces at this point. COMFEN I already mentioned; EnergyGauge, which has been an interface for DOE-2, is looking to move over to that. TREAT Plus, similar; ESP-r from the UK has been able to write its EnergyPlus files for a while. And you'll see others there. All these are listed and on our Web site. So if you're interested, we provide links. We don't do an evaluation of them, but we let you get to them and see them for yourselves.

The most important part is how do I get that really rich, robust information for my CADD or my building information model, my BIM model over to EnergyPlus?  And there's several ways. We've had in the past, and it hasn't been working recently, but we're hoping later this spring, to reintroduce a tool that will allow you to use the Industry Foundation Classes from the Building Smart or the International Alliance for Interoperability. It is limited to what the tools are exporting into their IFC model and, generally, that's been geometry. But we support the full IFC model in there.

Another tool that does export from CADD from AutoDesk Screen Building Studio allows you to do Web-based conversion of most formats and allows you to do energy simulation inputs, including EnergyPlus. It has somewhat limited coverage, again focusing primarily on geometry 'cause there's a lot of information there that you may not do there. Other ones to get directly from CADD EnergyPlus, we've been working with Graphisoft to get a tool to get information directly from ArchiCAD.

And Bentley, which has Microstation, recently bought two products:  HEVACOMP, which I mentioned earlier, and also TAD, and they're looking to more closely couple those with the Microstation products so they can get direct information from the BIM tool directly into EnergyPlus. I think that really, this is key. If we're going to get information from the BIN tools directly in the simulation tools, it's going to speed up adoption and make it easier for people not used to entering information in a simulation tool.

So I'd like to talk about one other thing that we've been working on, and this is – many of you may be familiar with Google SketchUp Program. Well, we've created a plug-in called Open Studio. SketchUp, for those of you who don't know, is really an intuitive, easy to use, 3-D drawing program. You see several things there. And talking with a lot of architects, they use it or a similar tool to really look at the building in early design to get the form of the building, to be able to render it well enough. And then they're able to export their model and move on into a full BIM model, while it's easy to manipulate and modify the building.

What made it interesting to us was this powerful application programming interface, or API, where we could actually access some of that information, the geometry. So we created a plug-in using programming, the Ruby programming language to do that. And that plug-in, we call Open Studio. It essentially adds the EnergyPlus functionality within SketchUp, and it works with both the free and the pro-versions. It's available at the EnergyPlus.gov Web site as well, and it's open source. So if people want to add capabilities or dig under the hood and see how it works, that's available to you as well. So that's available on SourceForge and we have links to that too.

The intent here is really to provide feedback during conceptual design. You may need something more detailed and your model may need to be more detailed as you move forward. But our focus, really, was early design where we can do that. Currently, it's focusing on geometry. We're working on a new version later this year. There'll be an update in April, also in October. October, we'll have much more functionality.

So let's look at doing something here. To start off, this is how SketchUp looks with the EnergyPlus tool built in. So if you look at the second set of tools, or the second toolbar, there's E and E-plus, etc. The new Energy-Plus Zone is pointing to a little box with blue and a plus – blue lines and a plus around it. You start off by clicking on that and then double-clicking there. You then start drawing your floor plan. You use the Push/Pull tool to basically extrude the floor plan. At this point, this is a totally functioning floor or a 3-D version of the tool.

You can use the rectangular tool, the rectangle tool. You see it pointed to there to draw windows and doors, and the tool knows that if you draw a rectangle attached to the bottom, that you'd expect that to be a door. If it's a rectangle in the middle of a wall, expect that to be a window. If it's in the roof, it's the skyline. And you can adjust all those, so it's very graphic and very quick to get something as quickly as that.

So here's looking at a similar tool. We pulled the toolbars off so you can look at it because it's three pieces here and we need to look at those. So you see, the longest one is the energy design command so that you can either create a new one, you can open an existing EnergyPlus file, add new zones, you can run simulations, etc. The energy design rendering allows you to actually apply the results of the simulation and we'll look at doing that in just a second. By using some of the powerful tools within SketchUp, the animation allows you to look at solar patterns and other things, and how the shading might be affected. So you can look at it at various times of day or even shoot a little movie of it.

So if you open the existing EnergyPlus file, here's an example. This is a model of the Chesapeake Bay Foundation, which was the first LEED platinum building. It's near here in Washington. It's over in Annapolis. So you can see there we have the building; we have the shading. See kind of the dark gray slanted panels there in the center; those are PV panels. So we've got it fully robust, with all windows in place and all the shading in place.

We can open and edit a file. This is a little file that we created using the sample file generator. It took about three minutes, including all those fins and everything. But I can select one of those surfaces to work on. I can edit it. I can change some of the information related to that, the surfaces related to it. The object info window you see here gives me information. You see the object text box, the biggest box there at the bottom. That's actually the information that the EnergyPlus uses directly. But we have certain other information that we can do that, so here we've got 942 square meters, 16.4 percent exterior glazing for areas, 600 square meters. And, of course, you can do this in English units as well.

You go into Editing Zone. You can select a particular zone; select it, change the windows, change properties. I can edit a particular surface. Here's another building that we've done some work on. So you can give it a name, change the type from the pull downs. You can give it what zone it's attached to, what exterior boundary conditions and other things related to it. Here's where you could say, "You know I really want to change that wall type to X," or "I really want to change that construction type to Y and really look at options here." You can do quite easily with this tool.

In terms of running simulation – it's actually just a pop up there, you can either run the full simulation or just run some design days or some example days to see what's going on. It allows you to select a weather file from where the weather files might be located on your system. And then you can report information in the bottom to the user variables and meters or the utility performance information, and also report zone temperatures, etc., so lots of information. Not as much as you might get from within EnergyPlus, but a lot nonetheless.

So when you clicked on run simulation, that's EnergyPlus actually running. And if you've got a copy of EnergyPlus on your program, that's what it will look like when it comes up and starts running. So it gives you a lot of control over what's going on in there and it doesn't require you to get out of SketchUp to be able to look at some of the adoptions and to look at the results.

Here, running a simulation yet again. And I mentioned earlier the data visualization. After you've done the simulation, you've asked for surface temperatures for example, or maybe room temperatures or something like that. You then tell it where that result is, browse to the data path and it'll tell you what simulation pieces are available and what data variables are available. So in this case we're looking surface outside temperature, hourly. And the inside variable name is the same, so we want to look at how that would apply there. In this case, we're going to use a hue scale going from blues through greens into reds, and allow us to be able to look at how that might apply.

If we were doing automation here, you would see a change with time as the sun rose and set and was under the surfaces. But so here's for example – this is placed a day in September at noon on this particular building. And you see the highest temperatures of 65 degree out on the roof surface, and even the wall temperatures are getting into the 30s. The wall temperatures are also getting into the 30s and 40s, well into the – over 100 degrees there. So you're able to look at that and see what the impacts would be of maybe changing that. Maybe I add shading or maybe I do something different, and you can look at that over time to see how to change the impacts.

The info tool is also available. It allows you to just hover over a particular surface, and you can see what it has in terms of its information so that it has a particular U-value. This one has a long construction name of a standard window, U-value of 3.124 with an SHGC of .14. But then you could go and right click on that and change that if you wanted something else. You see all the information there related to EnergyPlus for that building.

So the OpenStudio license, it's free. It is open source so that if you want to get in and mess with it you can. It was developed by National Renewable Energy Lab for us. Current version is 1.0.4, released at the same time as Version 4.0 of EnergyPlus. And we do update it every time because there are some changes in EnergyPlus that reflect it. And we are doing major developments of it over the next year or so, so we'll see some substantial changes. Not so many for April, but probably more in the October timeframe. It does work with both the free and pro versions of SketchUp, so you don't have to pay Google to use this. You can use their free version; it works fine. And since SketchUp's available for Windows and Mac you can work in both of those platforms as well.

So, really, our vision for OpenStudio in the design process – and remember we said conceptual design, early design, is really that second dash under Conceptual Phase, changes based on simulation feedback, giving you information about what's important in the building and how you could change that option to let you look at options for the form, and some of those things that got really tied down early and are difficult and expensive to change later are changed. That's really the key, to allow you to look at options, and give them to your clients and show them what the variation would be when you don't have a lot of design information, or a lot of information you would need for tools.

In terms of design development, you'd probably move up fro SketchUp to your CADD or BIM tool, and move forward there and continue design refinement. At that point, probably have either a closely coupled through an export from the tool back to EnergyPlus, or just maintain your EnergyPlus model as you make changes as your design evolves. Now if the building form's not going to evolve very much, that may not be such a big change. But if you're trying to swap out different types of shading or other things of major form, you may want to stay with a tool that will allow you to do that easier.

Some of the limitations, it's not really a full-featured interface, and it really wasn't intended to be. So it's not a competitor, per se, to DesignBuilder or HEEVACOMP. It's really intended to be – and right now, as I said, it's already focusing, primarily, on geometry, but it allows you to get the HVAC systems if you use some of the other tools there. It's also, currently, not a translator from SketchUp to EnergyPlus. So if you have a SketchUp model you can't just say, make that an EnergyPlus model. You've really got to already have the energy model in mind because there are a lot of things in your SketchUp model, like balcony rails and other things that aren't going to affect your simulation model, and you may want to exclude those from, like, when you're doing it. We are looking at trying to make it so it'll more easily auto translate the SketchUp file, but that's probably coming down the road in another year or so.

So what to watch out for the future, we want to say it is still being developed. It's pretty robust at this point. There are a few known bugs but we continue to fix those. You need to make sure if you're using it to click into the zone because I've seen a lot of people try to draw on a surface and they're not actually in the zone, and it winds up just being a pretty rectangle, not actually a window or a door in the space. There can be problems where you have a wall without a zone or windows with no subsurface, and those can be a real problem for that.

Undo doesn't always work, as you might expect, so you have to be careful and save frequently is our one thing. Make sure if you're getting – starting off with a base, save that base before you start modifying it for quite a bit. And synchronizing, sometimes, between the IDF and SketchUp files can fail, and in that case we always recommend you go back to the IDF and start from there. You also have to manually assign other side surfaces so that you can tell these two zones are next to each other. A lot of that will disappear as we move forward over the next year or so.

So, finally, I want to wrap up by telling you where you can get support for EnergyPlus and where there's help. There's the Web site, which we've been mentioning already. It's a free program download, all the documentation there. If you download the program you get that same file of documentation, but also, the validation reports are there as well – the weather data we mentioned earlier. And I do want to say ASHRAE is working on a project right now to add another 3,000 weather locations. It'll supplant many of these that are here. So I think we'll at least have 4,000, 4,500 locations by the time that project is done.

The developer and commercial distribution licenses if you want to do that, but those aren't required for just getting a copy of EnergyPlus. You can just download that and you don't have to have any special license there. For user support, we do have a help desk. It's email based, Web based, and you can do it either way. You can either go to the energyplus.helpserve.com and submit questions there on the Web, or via email and submit them to EnergyPlus-support@gard.com. You can attach input files there as well.

There's also a Yahoo group for this EnergyPlus support. It's been in place since, virtually, the beginning. We launched it right after we launched EnergyPlus. So there's, literally, thousands of questions that have been answered by users and the team on there. Currently, it's about 2,500 people on the list, so if you have a question there's usually somebody that has an answer. And we are letting this be, primarily, a user-to-user forum. But if you have a question, it's often a good idea to go there and do a search on it because somebody's probably asked that question before. You can join it by going to the link you see there or just by subscribing and sending an email. So that's possible there.

And, finally, I want to thank you for your time. And I think we're ready to start answering your questions. We've got a few in today, but you see the links to both the Building Technologies and EnergyPlus and OpenStudio.

Question and Answer Session
What are the computer requirements for EnergyPlus?  The computer requirements are not that stringent. But we have found that the more memory you have the better off you're going to be. If you're dealing with a Vista or Windows 7, of course, you're going to want to have more memory there. But I run EnergyPlus on my laptop, which has only a couple gigabytes of memory and only a 1.2 processor speed. So and that runs fine. The faster the processor, the faster the hard drive, the faster you'll get EnergyPlus. And we have some of the information there in our Getting Started guide.

When using EnergyPlus and SketchUp, are there significant differences in functionality between the free and Pro version of SketchUp? No, there's not really any difference for EnergyPlus within the OpenStudio. The free and pro versions really are – the differences are more in the functionality of SketchUp, itself, not in the OpenStudio. Those allow you to do things like import and export a particular file or formats, and CADD and BIM formats and other increased functionality not related to EnergyPlus.

What are major new releases of EnergyPlus for next release? We haven't put a list together. I know that we're working several. Wind turbines is being looked at to adding there, and there's some other enhancements, a lot of other things. I don't have a list of that, but we will here in the next month or so.

Question on a specific application. This person wanted to know whether EnergyPlus covers variable-flow refrigerant systems such as those from Mitsubishi. And the answer to that is no, but we are working on it. We've been working with a number of the manufacturers who have these variable-flow refrigerants and variable systems which use refrigerant as the mode of getting the heating or cooling around to the equipment in the spaces. And we're expecting some of that functionality, we think, will be available by October.

Can Trane Trace modeling results be imported into this program? No. Trane Trace modeling results, really, is separate. I believe there's a capability of using, for example, Green Building Studio to take a model into Trane Trace, but there's not really any translation from Trane into EnergyPlus.

Is eQUEST an interface for EnergyPlus? No, eQUEST is an Interface for a private sector version of a tool called 02.2 and does not currently do EnergyPlus.

What are the most common design changes made to a building after using EnergyPlus? Hmm, well a lot of different things, but I would think that some of the easiest things to do looking at EnergyPlus, in particular with OpenStudio, are things such as changing the windows, maybe adding shading, looking at different efficiencies of equipment, overall changing, tweaking the various pieces. Within the OpenStudio environment, as you're changing the shape of the building, you could look at options such as shading and other things directly there.

Does LEED support using EnergyPlus for energy modeling? Does energy modeling help with LEED points? Yes, LEED does recognize EnergyPlus as one of the qualified software tools for doing energy modeling. And yes, modeling is one of the ways you can get points in new construction for doing that.

Would you recommend doing energy modeling at the conceptual phase with OpenStudio and continuing through the CADD stage, or is the conceptual stage sufficient? Actually, I think it's very important to continue simulation throughout the design and construction phase and even into operations. Simulation is giving you a really powerful tool for helping people to operate buildings. We've seen that in a number of cases where we've been able to use EnergyPlus in some of the tools. Our labs are built around it to help debug control systems, and fix things before buildings were built and actually help them work better, and, also, to debug the operation of the building and figure out what's going on there.

We also see substantial changes throughout design and there are lots of things that influence energy beyond conceptual phase, so that you would really need to look at. So the selecting windows and selecting efficiency of equipment, and how that's configured and how controls are done are all done later in the design. And you'll miss that if you just stay with it through conceptual phase.

There was a question about training opportunities. The user says, "I'm not that experienced using EnergyPlus. Can you recommend any training courses for me?"  We do host a number of training courses. We try to have at least four or five in a year. We haven't settled on one yet this year, what we're going to do. But we post links to those from our Web site, so if you can go there there's a link to our main provider for the courses. If you're interested, we can provide a custom course for an organization or say, if a local association or professional society chapter wanted to be the host for a workshop, we'd be happy to do that. We've done that for both.

Next question:  Somebody asks whether there were any video tutorials, that they've used ones for SketchUp before, and were – any of these exist for the EnergyPlus plug-in. And the answer is yes. And you'd have to go to the American Institute of Architects' Web site to find that. We did some work with them, did some free courses at the last AIA Convention and are planning to do some more at this next one. These were recorded and so that they are – you can follow them on line and, also, the course material. It was, like, a four-hour course to get started in EnergyPlus and OpenStudio to work with that.

Next question:  How applicable is the tool for existing buildings, especially integrating with a walk-through energy audit? Well, an existing building, you need a lot more information and a lot more specific information than you would need if you're doing design. And you'll have a lot more information, so using an energy audit to collect that information is actually ideal way to get there. You often may have an existing CADD model of the building. Or if not, you can even start with something as simple as going to Google Earth or other things, and literally finding the shape of the building and being able to create something there. There are tools for doing that.

Next question:  What if EnergyPlus doesn't address all the features of my building? Can I add new technologies easily? We're working to make it easier to do that, but I think a lot of the features and the capabilities that you probably would need, with the exception of things we know are not there, are handled by this runtime language that allows you to control things in a different way and have them act differently than you would otherwise. EnergyPlus, it's not all inclusive, otherwise we'd say we were done. And we have a list of enhancements that we continue to work on every year to do that. It is possible, and we've had university grad students add capabilities to EnergyPlus.

In fact, a couple of universities are involved on the team. For example, Portland State University added the green roof module a year or two back and are continuing to enhance that, that you can look at the impacts of having the green roof, and water storage, and rainfall and all the parts there. We also have a similar one where a grad student in the UK, at the University College in London, added a heat and moisture transfer model, very robust model to really add that capability to look at moisture transfer and how that interacts within the building.

It is possible. A lot of the grad students we have working with us at universities are doing specific things. So they may be doing a wind turbine; I know one's doing one now. We've had other places doing others. But it does take some programming knowledge. And we don't really have a scripting language that makes that easier to do right now, although we are working on it.

Now let's see. It says could you please tell me again, is there any tool that converts ISC to EnergyPlus IDF fully? The answer right now is no. We did have a tool for the first few versions of EnergyPlus and we were having significant problems, not with our conversion tool, but with the middleware which read the IMC file. We believe we have those fixed and are hoping to get that out this spring. We're doing some testing right now of that to make sure it's robust enough support. Hang on for another month or so, and I think we should have some by the next release.

Will an OpenStudio model in SketchUp transfer successfully into a HEEVACOMP model in Microstation? We are concerned with maintaining the information model from schematic design to the design development and beyond. I would say that a SketchUp model transfer directly to Microstation. And that's one of the things that the pro version of SketchUp allows you to do is to deal with those. Sometimes you can get those conversion add-ins from Bentley or the other vendors to be able to do that. But OpenStudio wouldn't transfer directly into HEEVACOMP. I do believe that HEEVACOMP will read an EnergyPlus file, and so you could take your OpenStudio EnergyPlus file and bring that into HEEVACOMP to continue working with it. And you're right, it is really important to keep that information model moving forward, so BIM is critical there.

Can EnergyPlus do thermal comfort analysis like PMV and to what extent? EnergyPlus actually has quite a few different models. It's got PMV and it has other – other ones, Kent State, and other models there. So we do look at radiant heating and cooling aspects on the comforts as well as direct solar radiation, so you can estimate that. We actually have reports which will report out how comfortable an occupant would be according to ASHRAE Standard 55, so that's on the reports, so quite a bit of capability. You can report that out at the time step. So if you want to see how comfortable and when people are uncomfortable, you could look at 15 minute or even 10 minute data if you really want that much data.

Does EnergyPlus model various levels of occupancy? The answer to that is yes. It's one of the inputs so that you can tell it how you want to treat occupancy, when people are going to be in there, what sort of activity they're going to do, how they're – if they're, you know, in a gym so they're putting off lots of heat, or if they're just in an office so they're more sedentary. And you can control that with the schedules and also trigger it on other things. You use that as a surrogate for other things.

Next question:  Do you see IDF files as a compliment or as a substitute to gbXML files, BIM files and IFC files? I think they're a compliment. They're not really a substitute for either gbXML or BIM or IFC because each of those has a different piece. The IFC and the gbXML are trying to get simulation related information in or model information in a way that other tools can use them, so it doesn't have to be just a BIM tool or an energy simulation tool. It could also be a cost tool. If you want to share information, what's the area? How much is going on there? I can estimate the cost. So, really, it's a compliment. That interoperability and to be able to share the information is still pretty critical.

In the future do you envision EnergyPlus using BIM models direct to perform analysis without having performed conversion or translation cost data file formats? I think you're going to see more direct use of it, but there needs to be some discussion about how much information. BIM model has a lot more information than you need in that particular building. Do you really want to model each and every room as a separate space? In my own office, on the floor I'm on, there might be hundreds of different zones. Does that really make sense? Or could you group those together thermally because they all act the same on facing the south side, for example, or the west side. So you need to have some sort of simplification, whether it's automatic or otherwise to really be able to do that. The answer is yes, I really do see that we're going to see more tight coupling of the BIM II, the simulation tools. And you're seeing that already, and I think that's one of the reasons we're seeing the BIM developers purchase things like Green Building Studio on AutoDesk's part or HEEVACOMP on Bentley's part. So there's really an interest there, and Graphisoft has done some of the things as well.

So let me see, more questions. Can you account for CHP or combined heating and power? And the answer is yes, you can actually do district heating and cooling as well. You can do combined heating/cooling power so that you emulate a system that's producing power as well as heat or cooling for a particular building or maybe even a complex building, so that is possible.

Next question:  What about ground source geothermal modeling? There are a number of models in here. There are vertical wells, horizontal loops, and we're looking at introducing – we've had some research about using the excavations that you would normally do for foundations, including the loops, directly in there. We're doing some field measurements now and looking to put some of those models in. So the answer is yes, we can do that. We also can use the ground to do earth tempering, so you can draw outdoor air into an earth tube and model that impact as well.

Can you do calculations with landscaping? Landscaping – you can calculate the amount of water that is collected based on information either in the weather file – and I have to say there's very little rainfall information in any of the weather files. Trying to produce that, we have done some general information and you can even put your own stream of rainfall in there if you want to. But it will allow you to deal with vegetated roofs, and the amount of water that's needed, and, also, storage and use for landscaping as well. So there are cisterns, and wells and other things you can do with water.

How does this program interface with Labs21? Well, as I understand it, Labs21 is really focused on energy efficiency in laboratories and where they have a lot of outside air and ways to really improve that. And EnergyPlus can simulate the laboratories and how that – the large amounts of outside air and other – the pollutants all could interact so you can't do that. Interfacing directly with Labs21, I'm not sure that it does that.

Let's see. You mention that EnergyPlus can simulate on a sub-hourly basis. Could it be used to estimate room temperatures and relative humidity on a minute-by-minute basis in a room or a zone served by an oversized DX unit, for example? The EnergyPlus sub-hourly will go down to ten minutes. It actually will run lower than that, but we've limited the simulation to a multiple that can be 60, multiple 10 times 6 is 60, for example. So you can do 10, 15, 20, 30 minutes as far as your sub-hourly. It could be – you can, though, look at the system level and get the information at the point at which the DX unit is turning on and turning off so you could look at what's going on there. But yes, you could look at what's going on in temperature and humidity in a room served by an oversized DX unit to see what the impacts of that are.

So I think, at this point, I'm supposed to turn you back over to Anthony and to wrap up.

Anthoney Perkins
Dru, thank you very much. You know, as I mentioned, we have two additional polling questions to go through. So we're going to go to the first question. And it asks you about what you were hoping to learn today. And we'll leave this up for a few seconds, so if you'll go ahead and vote on the first one. We're going to go ahead and close this one in a moment, so please vote now.

Now we're going to go to the last question regarding today's training, so if you'll take a moment and vote for this. I'll give you another few seconds to choose your answer. Okay, we're going to close this question. And we want to thank Dru Crawley for his time today. We'd also like to thank all of you for participating.

Please visit www.buildings.energy.gov/Webinars.html to get a copy of the slides, and also check back to this Web page for the information for future building technology program Webinars. This concludes our presentation. Thank you and goodbye.

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