Architecture Student's Guide to Energy Modeling (part2)

We're back! This post continues from the previous one. Now for the less-architectural part:

1. Open EPLaunch. This comes automatically with your EnergyPlus download and may have been given a desktop shortcut. In the upper part of the window, browse to your new *.idf file.
2. Click the button that says "IDF Editor". This will open an index to the text file that contains all the model input information. The items on the list are called "objects", and as you scroll down, you'll notice the geometry you built in OpenStudio. (Note: at the time of this writing, the IDF Editor is the only element of the EnergyPlus set that is not available for Mac OS. This is expected to change, however).
3. If you like, select View --> Inch-Pound units. Otherwise, everything will be in metric units.
4. Scroll down to the section called "HVACTemplates".
5. The first item in the list is "HVACThermostat" - your zone needs a thermostat so the model knows how warm or cool to keep your zone. Click on it, then on "New Object" near the top of the IDF editor. A set of white cells will appear.
6. Give your thermostat a name, anything you like. For "Zone Name", select your zone's name from the drop-down list (click on the first cell to reveal the drop-down list).
7. For now, set the Heating and Cooling Schedules to BLANK (an option in their drop-down lists) and provide constant heating and cooling setpoints, e.g. 68F for heating and 76F for cooling.
8. The next item in the section is "HVAC:Zone:IdealAirLoadsSystem". This is the magical tool that will calculate heating and cooling loads for you, without a modeled HVAC system.
9. Click on that item, then on "New Object", and another set of white cells will appear. For "Zone Name", select your zone from the drop-down list; for "Thermostat Name", select the thermostat you just created.
10. Still in the IDF editor, select Save As and give your file a new name. You may have to add the .idf extension.

Yea!! You've just finished the part that scares most people away from EnergyPlus. You may have noticed all the objects related to materials and internal loads - you can easily learn to edit these to model the insulation, lighting, occupancy, and other characteristics of the zone. For now, though, let's accept the default values for all of those and go ahead, since we're just comparing massing options.

1. Go back to SketchUp. Within OpenStudio, open your new *.idf file.
2. Go to OpenStudio --> Run Model. There's also a button on the toolbar to do this, which looks like a red lower-case "e" with a blue "+".
3. A window will open asking you for a weather file. Browse to your favorite weather file (C:\EnergyPlusV4-0-0\WeatherData).
4. Make sure "Annual Simulation", "Report ABUPS", and "Show ABUPS" options are checked.
5. Click "Simulate" at the bottom of the window. A black DOS box with white letters will scroll by, and then your reports will appear. The total annual energy, and energy by heating and cooling load, will be the data you compare among different massing options.

Whew! The first time through this might take 2-4 hours; after that, it should only take a few minutes after you build the geometry in OpenStudio. Try opening some of the example files provided (C:\EnergyPlusV4-0-0\ExampleFiles). Those marked "Benchmark" are the most complete. Numerous tutorials for EnergyPlus are available online, and these can teach you to edit input objects directly so that you can accurately reflect internal heat gains, lighting gains, daylighting, etc. Good luck, and please post a comment if you have any problems so I can help out. I would love to hear your results!

Architecture Student's Guide to Energy Modeling

While I was an architecture student, I felt certain I was missing something in the world of energy modeling. Two courses on Environmental Control Systems taught us how to calculate simple heat gain and loss, shading, dew point position within a wall, bulk air flow, and so on. But these couldn't tell us how the earliest alternatives considered in design - massing and orientation - would compare annually in a particular climate. We were told, "Make it long and thin, and orient it east-west", but that was hardly satisfying for every site and every program!

I experimented with Ecotect, TAS, IES Virtual Environment, Demeter, Green Building Studio, eQUEST / DOE2.1, and everything else I could find at the time (2006-08). They all had their cool features - Ecotect's graphics were fabulous, even then, for example - but none delivered a simple, direct answer to the question: which form and orientation will give the lowest annual heating / cooling / lighting load on a particular site? And how much worse is the next-best option?

To be sure, several of the tools above can this question, if you have the time and inclination also to model the complete HVAC system and plant, and if you have a Windows operating system, and if you can afford the license (though student licenses are less than $100). Architecture students definitely do not have the time, even if they have the inclination and ability; they also tend to prefer Macs. The same is true for practicing architects.

So imagine my complete delight, last month, when I finally found the tool I'd been looking for all these years. It's EnergyPlus. Are you surprised? I sure was! One of the first building consultants I met, at SimBuild 2008 in Berkeley, was openly nervous about learning it. But for answering the massing-and-orientation question, it's easy. Here's what you do:

1. Download EnergyPlus (it's free)(and it works on Macs!).
2. Download some EnergyPlus weather files of interest.
3. Since you're an architecture student, you already have SketchUp. Good job.
4. Download OpenStudio (it's free too). Make sure it lands in the SketchUp plugins folder.
5. Download xEsoView (optional; also free).

Take a break. The next part might take a few tries, but it's worth it.

1. Open SketchUp. Look for the Plugins menu; if it's not there, OpenStudio didn't land in the Sketchup Plugins folder. But we'll assume it did.
2. Click on "OpenStudio" in the Plugins menu and go down to "New Zone Tool". Click there. The cursor will change to a little + sign.
3. With the + sign, click anywhere in the drawing field, placing the point, and then double-click on that point. A black dotted box will show up. This shows that you're drawing a thermal zone in OpenStudio. With the rectangle tool, draw a floor rectangle inside the black dotted box, and use the push-pull tool to extrude it into a box.
4. Draw a rectangle on one of the faces of the box - it should automatically become a transparent window. If it doesn't, you probably left the plugin - double-click on the thermal zone until the black dotted box shows up again, and keep trying.
5. Open the Outliner and watch as you create, reshape, and delete thermal zones. Practice until you can easily make, adjust, and delete thermal zones and their windows. Try right-clicking on a surface, selecting OpenStudio, and then selecting Object Info; notice that construction details appear, as well as the surface name.
6. Save a file with one thermal zone and perhaps a window as a *.idf file. Do this within the plugin, e.g. OpenStudio --> Save As --> Bauhaus.idf.
7. If you're curious, check out the Yahoo and OpenStudio support groups for their insights.

Great! Time for another break. Let's finish this up on the next post.

A Building, and a Database, to Watch

The US Department of Energy High-Performance Buildings Database is an intriguing source of information for green design. On the positive side, it presents design intents (including architectural vision) and performance strategies for 125 progressive buildings, as well as links to sources and contacts. On the other hand, many entries dwell on the acquisition of LEED points, present only modeled performance "data", gloss over any interesting prob

lems that may have arisen, and show no evidence of post-occupancy investigation.

At least two of the buildings in the list, however, present honest, detailed, useful accounts of their experiences: the Adam Joseph Lewis Center for Environmental Studies at Oberlin College and the Environmental Technology Center at Sonoma State University. Interestingly, these are both university buildings dedicated to environmental studies; with luck, more submissions will follow their ex

amples! Here is a bit about the first one.

The Adam Joseph Lewis Center for Environmental Studies at Oberlin College. With a design team led by passionately idealistic professor, David Orr, equally visionary architects at McDonough + Partners, and outstandingly generous donors in the Lewis family, this building was privileged from the beginning. Few of its contemporaries would be able to support a living machine, for example! But many of its features are widely relevant:

• elongated form to maximize permeability to light and air
• east-west orientation to simplify shading
• passive solar heating design incorporating thermal mass (not a simple choice in a cold winter climate)
• radiant heating in large open areas, such as the atrium, that have high infiltration
• a geothermal heat pump
• daylighting with photosensors to dim electric lights
• an outstanding low lighting power density of 0.9 W/sf
• automated operable windows for passive ventilation and cooling
• demand (CO2)-controlled ventilation to save fan energy
• very expensive highly-insulating glass
• a stunningly large 4,000sf photovoltaic array (an imperfect answer to the ideal of "sustainability")

All of these features have been debated in projects I've worked on in the last year: they are gradually entering the mainstream, and owners and architects are in need of solid precedent studies.

The exceptional part of the Lewis Center effort is the commitment by both Oberlin staff and students and NREL scientists to evaluate the performance of systems in their contexts, to make both big changes (e.g. replacement of the original electric boiler with a ground-source heat pump) and small ones (controls adjustments) and to track the effects of changes. An excellent real-time display is provided on the Oberlin website, and field work results by Paul Torcellini and colleagues at NREL are also now available.

So: how well does this building perform? The answer is: quite well! It has an EUI of about 32 kBtu/sf-yr, met entirely (on an annual basis) by the PV array. This is about 1/3 of the EUI of other Oberlin buildings. Is it "really" net-zero? Some purists argue persuasively that the point of a net-zero building is not to offset energy use with enormous arrays of silicon wafers, glass, and metal. We're working on a net-zero K-12 school now that's seeking the same vast-PV solution, understandably - getting heating loads down, after a point, is just really, really hard. In any case, Oberlin has taken a fantastic step forward for all of us - not only by creating this progressive building, but by sharing their experiences, good and otherwise, with all of us.

Five Essential Roles for Performance Research

The Scandinavian hospital study illustrates a few unique contributions of building research, that energy modeling, commissioning, and system monitoring cannot offer:

1. Understanding of design intent.

The vision of the design team - owners, stakeholders, architects, and engineers - has a permanent impact on the energy performance of a building. Siting, geometry, orientation, envelope materials, organization of the program, spatial configuration, and environmental control system choices all reflect this vision, tempered by constraints of time, money, and building codes, and all have substantial impacts on the energy needed to heat, cool, light, and ventilate the building.

The effects of these key performance-affecting decisions are so decisive, and so long-lasting, that we must understand the forces that shape them in the design process. This element is therefore a cornerstone of building performance research.

2. Systems-level analysis.

Buildings operate as complex systems of people, machines, structures, and climates. Since these elements affect building performance as an interacting set, a clear understanding of building performance necessarily requires investigation into the operation of the system as a whole. Energy models do simulate buildings as systems, but their best role is to inform decisions among a limited set of design alternatives; they are definitely not diagnostic tools. To understand the operation, and especially the malfunction, of a real building requires field investigation.

Revealing unexpected activities of occupants, and understanding the origins of these activities, is an especially important aspect of field research. Unprogrammed use of spaces, manual overriding of system controls, and propping openings open or closed are just a few ways that occupants can unwittingly diminish the energy performance of their building; tracing these to their motivations, and then to concrete aspects of the building design or operation, is an essential component of systems-level building research.

3. Pattern discernment through comparison of multiple buildings of a type.

Each building is substantially unique: despite common elements, a particular assembly of spaces, materials, climate, program, and occupants is rarely duplicated. This complicates efforts to determine which performance strategies work well, and which don't, in a particular building type. Yet, as the Scandinavian hospital and High Performance School studies show, patterns do emerge when enough examples of a type are compared.

The seeking of patterns among multiple examples of complex systems has excellent precedents in field ecology (see work by E. Odum and J. Lovelock) and in architecture (C. Alexander, A Pattern Language). Their field techniques and analytical tools are directly applicable to building systems, as well, and should inspire us toward a "comparative building ecology" that illustrates performance patterns, in their contexts, robustly.

4. Controlled experimentation.

Although every building is an experiment of one, some experiments can be conducted within a building, nonetheless. Energy use of analogous spaces that differ only in occupancy or equipment can be compared; conditions in individual spaces can be tracked through varying seasons; passive airflow paths can be obstructed or cleared; light shelf sizes and angles can be varied; setpoints and schedules of mechanical systems can be adjusted, for example. While such adjustments are often undertaken by facilities managers, rarely are the results of individual changes tracked over time to yield meaningful information. Such experiments might also be simulated with models; an intriguing document by the New Buildings Institute presents such analysis for large buildings. Given the limitations of models, however, the realm of controlled experimentation remains an important one for teasing apart relationships among spaces, people, and environmental control systems in real buildings.

5. Publication.

The ultimate goal of pure research is to publicize the results, so that a wide audience can learn from them (where "publication" includes meetings, talks, discussion forums, and websites as well as design and science journals). In contrast, commissioning reports and building energy models are private documents; indeed, building designers and owners are understandably reluctant to publish evidence of performance below expectations.

At the same time, the disclosure of design decision pathways, model predictions, operational realities, and performance outcomes would help future design teams immensely. This, therefore, is the most important of the unique contributions that building performance research has to offer: the provision of reliable information, obtained through rigorous investigation and experimentation, unbiased by financial or legal interests, in straightforward, accessible forms with the strength to change common practice.

What Does Performance "Research" Mean, Exactly?

If "research" means original research, and if buildings are created from principles of spatial design, climate responsiveness, structural stability, heat transfer, fluid mechanics, and hydrophobicity, among others, that are already known, then what, exactly, does "research" mean in the context of the built environment? What else is new, in these constructions, that we have yet to learn? More specifically, what can we learn that is generally true, and generally applicable - that can inform the design of future buildings?

To an architect, there is still quite a lot! To a social scientist, there is an equal abundance. But in terms of energy performance...what can original research really offer, that energy modeling or commissioning or just system monitoring cannot?

One study that's influencing our current work is still in progress by members of the University of Washington Integrated Design Lab in collaboration with BetterBricks and I-Sustain. Several additional people, including NBBJ architects and my boss, have also been closely involved. In this work, the group investigated a number of different Scandinavian hospitals, analyzed their geometry, orientation, layout, loads patterns, envelopes, hvac system design, and energy usage, and distilled a series of truths from the results that are evidently unknown to the US hospital design community. (One of their subjects was the Martini Hospital, above). This will be a fantastic resource when it's published!

One striking result, for example, was the superior effectiveness of decentralized ventilation systems in combination with radiant heating and cooling. While the inherent wastefulness of VAV reheat systems might seem obvious, with its strategy of cooling air to the lowest temperature needed by any of the zones served, and then reheating it locally for all the rest, the vast majority of American hospitals are designed with this exact system type. The next question, of course, is why? Are they cheaper? Easier to install? More reliable? Or just "the way it's always been done"? There must be some obstacle out there to changing common practice.

(to be continued...)

Building Performance Investigation Doesn't Pay - Yet

Today I was investigating trendlogs for the under-performing LEED building, trying to figure out why air-handling units were misbehaving in various ways, when my boss startled me. "Stop working on that!", he exclaimed. "We have to watch the budget REALLY closely on this one!" Considering that we were only 8 hours into the project, this was rather unexpected. We clearly have an exceptionally small budget to bring this complicated 150,000sf building into line with its energy model - and this is a building that has gotten the best that money can buy from the very beginning.

So if THIS privileged building isn't worth more study, even to save thousands of dollars a year and to gain its last (necessary) M&V point, where do the thousands of other green building hopefuls find incentives for maintaining their performance goals? That is, before a dramatic energy crisis solves the problem for us?

Since we're already discussing LEED issues, a closer look at the LEED v.3 Minimum Requirements is worthwhile, and is mildly encouraging. For new construction and major renovations, Item 6 reads:

ITEM 6. Must Commit to Sharing Whole-Building Energy and Water Usage Data

All certified projects must commit to sharing with USGBC and/or GBCI all available actual whole-project energy and water usage data for a period of at least 5 years. This period starts on the date that the LEED project begins typical physical occupancy if certifying under New Construction, Core & Shell, Schools, or Commercial Interiors, or the date that the building is awarded certification if certifying under Existing Buildings: Operations & Maintenance. Sharing this data includes supplying information on a regular basis in a free, accessible, and secure online tool or, if necessary, taking any action to authorize the collection of information directly from service or utility providers. This commitment must carry forward if the building or space changes ownership or lessee.

While this commitment is still technically voluntary, certification can be withdrawn for failure to comply. Still, the performance is not required to reach or, apparently, to even approach the performance originally predicted. Even to gain Monitoring & Verification points, it is only necessary to "Provide a process for corrective action if the results of the M&V plan indicate that energy savings are not being achieved."

The issue of confidentiality was also broached, and real estate lawyers are already taking note. Apparently the ugly jungle of building design lawsuits has just added a fertile patch of soil.

Meanwhile, I was immediately reassigned to a new project: construction of a DOE2.2 energy model for a large ambitious new building, not so very different in program from the troubled LEED building. It's in schematic design, of course, which means that a large number of important details are completely absent. Energy models are valuable tools, and this model-building exercise will surely be a useful tool to guide the architects. Unfortunately, it will surely not predict the actual energy performance. But it sure does have a nice big budget.

Nature Calls

On September 10, the prestigious journal Nature published a commentary entitled "Overrated Ratings", in which it criticizes the LEED green building award system for falling short in promoting design of low-energy buildings.

"...as is well known in the building research community but not outside it," the editors write, "neither LEED nor any other such rating is a reliable guide to energy performance. Labelled buildings often perform no better in energy terms than the general building stock, and sometimes worse."

Sometimes WORSE. How is that possible? True, the original LEED system weighted energy performance rather lightly, giving nearly equal weight to site design, water and waste management, and green materials. But these should not be causing the energy use to be occasionally WORSE than average, especially since the energy performance of every LEED building must be modeled if it is to gain energy points.

Here, unfortunately, is the problem, as the editors continue: "most ratings assess a building's energy performance using theoretical projections from engineers' models, but don't measure its real, post-occupancy performance, which often can be much poorer."

Indeed.

My colleagues and I have just begun work on a project with this exact problem. The building was awarded LEED Gold two years ago, in part through energy points gained with a careful, thorough DOE2.2 model that used the best information available at the time (i.e., pre-occupancy). Two years later, this beautiful building is using about 20% more energy per year than modeled. Twenty percent. This is not the kind of error that results from occupants squeezing a few more people into a space than projected, or cranking the thermostats up a few degrees. This is a sign of pervasive use of building spaces and systems in ways very, very different than intended by the owner, designed by the architects and engineers, and yes, simulated by the modelers.

Why are we doing this? Because, thank goodness, LEED 2.2 has a "Monitoring and Verification" point that this building needs to keep its Gold label. The teeth are sharper in LEED v.3.

We don't know what the problems are yet, though we have some preliminary ideas. We believe they will be relatively easy to identify, though we fear that some of them result from conflict between design intents and occupants' reality. Most of all, though, we hope that this effort will become part of a new, larger, and sustained national effort to evaluate the performance of not just LEED buildings, but all new green buildings, and vast numbers of green-ing existing buildings as well.

Every Building is an Experiment

Scientists always replicate their experiments. No journal would publish their work if they didn't. Field ecologists agonize over finding comparable niches, hoping that statistical analysis will tease truth from the daunting variability of the natural environment. Chefs try a recipe repeatedly, adjusting ingredients minutely, to find the perfect taste. Athletes and musicians practice moves and passages over and over, striving for the subtle nuances that will make all the difference in the final performance.

But in architecture, every building is its own experiment. With rare exception, it is an experiment of one. (The earth is also an experiment of one.) No controls, no replicates, just one glorious culmination of years of hopes and ideas and struggles to get the thing built. And what of its performance?? Spatial performance is rewarded with glossy features in Architectural Record or Dwell. But "Star-chitects" like Peter Eisenman notwithstanding, energy performance is also a very real concern among designers! Buildings use enormous amounts of energy, and as a result, enormous effort has gone into programs to promote green building design: LEED, SEED, Architecture 2030, International Living Building Challenge, to name just a few. Buildings routinely win awards, gain certifications, and advertise themselves as "green" on the basis of design alone. Think of how astonishing this is: would a recipe, a music composition, a dance, a space, win awards without ever being experienced?

To be sure, building performance can be predicted to some extent from digital models. I build DOE2 and EnergyPlusmodels for a living, for example. They are valuable, even essential, tools. But they are not the whole story. Each model is only as good as the information that goes into it, and information is always incomplete in schematic design, which is when most building energy models are built. Elements get changed in design development without re-analysis. Decisions are re-visited during construction, materials are substituted, mistakes are made, budgets are cut, timelines are quickened, and occupants use the building in unexpected ways.

But what about that performance? Isn't the final performance important enough that we actually go check, to see if the experiment worked? Actually - no! Tragically, most buildings never receive any greater performance assessment than the owner's monthly glance at the utility bill. This is tragic because vast resources are invested in buildings, because thousands of green buildings have been built in the last decade and thousands more are on the boards, and because the lessons available from those we've built are not even being listened to, with a few laudable exceptions (such as those published here and here), so that new ones can benefit.

This blog exists to celebrate the green building agents who are out there listening, to identify new green buildings most worth listening to, and to help get their messages out to designers.