Using ASHRAE 90.1-2004 Models to Estimate 2007 Edition Reductions

If you read this post within the next five minutes you'll get our Super Bonus 2030 Challenge Code Equivalents Included free of charge!*

I've been helping our project architects put together a federal proposal right now. The DoD requires a detailed narrative based on ASHRAE 90.1-2004 to show compliance with the Energy Policy Act of 2005's 30% reduction requirement, but they also require us to complete a proposed LEED-NC 2009 checklist which bases points on the new ASHRAE 90.1-2007 standard.

I understand that 2007 is more stringent, but understandably, the mechanical engineer doesn't want to rework the entire baseline model for a project we haven't even been awarded yet! I decided to see if I could find any rough estimates for this online, and sort of succeeded thanks to the 2030 Challenge.

Wrong challenge... as if anyone would want to drink Pepsi anyway.

Figuring out if you've complied with the 2030 Challenge's interim requirements is no small task, so Mr. Mazria got a few smart folks together to create a document that shows what you have to do using existing codes and standards to meet the then relevant 50% reduction in energy use over 2003 averages. Unsurprisingly, they called the document "Meeting the 2030 Challenge Through Building Codes.

Get to the Conversion Already

Luckily for us, this document features both the 2004 and 2007 ASHRAE 90.1 equivalents, and from there we can draft a very rough approximation of a conversion factor. The folks over at the 2030 Challenge wrote that exceeding the 2004 standard by 30%, and exceeding the 2007 standard by 25%, are both roughly equivalent to the interim 50% goal, so logic would dictate they felt that these are also roughly equivalent to each other.

So... running the numbers we see 25 / 30 = .8333 multiplier if you're using a 2004 reduction you wish to translate to 2007. If for some reason you needed these in reverse 30 / 25 = 1.2 multiplier to take a 2007 reduction and translate it to the 2004 standard.

I should point out that this factor should probably be taken with a grain of salt. The complexities of the modeling process, namely that the baseline is a shifting target dependent on system selection, would indicate that this is at best imprecise and at worse horrendously inaccurate. At the moment though, I suspect some of you could use such a tool for estimating points early in the design process.

If any of you modelers out there wish to tell me how wrong I am, please do so by leaving a comment for all to see!

*Technically it's always free of charge, and I've recently come to learn all Architecture 2030 publications are free to the public.**

**[EDIT 01/25/10] I originally had a "A $69.99 value!" listed as the footnote as a joke, but some alert folks over at Architecture2030 did not want readers to get the impression that Architecture 2030 charges for their publications. You'd think a non-profit institution like the USGBC would be wise to consider a similar strategy!

Greenbuild Session Review: Cx & EM – Value, Cost and Project Integration

This session featured quite a few notable minds (the term “dauntingly prestigious” was used at one point) and featured some telling audience surveys, with a packed crowd (somewhere above 1,000) mostly but not exclusively composed of designers and engineers (many owners/facility managers included in the audience as well).

Energy Modeling

• “Is energy modeling a necessary cost or mandate of LEED?” 70Y 20M 10N
• “Is energy modeling too expensive for the outcome delivered?” 10Y 45M 45N
• “Is the scope of energy modeling commonly understood?” 10Y 30M 60N
• “There aren't enough energy modelers.” 70Y 20M 10N
• “Energy modeling is not predictive of building performance.” 60Y 30M 10N
• “There is no passive thermal modeling available.” 85Y 10M 5N
• “Energy modeling increases standard of care for the design professional.” 50Y 30M 20N
• “Energy modeling helps justify investments and convince clients.” 95Y 5M 0N
• “Energy modeling supports integrated project delivery.” 75Y 20M 5N
• “Energy modeling supports informed choices.” 90Y 5M 5N
• “Most tools do not reflect the most innovative system designs.” 80Y 20M 0N

The end result of these survey questions was a discussion loosely focused around the following quote: ”Energy models are not particularly good at determining absolute energy use, but do a good job of comparing scheme A to scheme B.” This comment was quickly followed with a discussion about how we need tools to foster energy prediction. There is a strong need to get a detailed and ACCURATE understanding of the schedule of occupancy and how the building will be operated. Ultimately we have to model human nature (How far into Fall are you going to just leave the windows open instead of using a heater/AC? Is that typical?), and there aren't very good metrics or processes for getting this done.

When asked what the USGBC should due to respond to these issues, there was an excellent comment from the panel that right now all of the training is taking place in practice, and as a result there's no time for people to really explore and understand the software. There needs to be an emphasis on getting this training into the college degree programs where there aren't time (read: money) constraints. How the USGBC can foster this is up in the air. ”All of these comments have a common theme: a lack of consistent methodology.”

Commissioning (Cx)

• “Cx is a necessary component/mandate of LEED.” 99Y .5M .5N
• “Is Cx too expensive for the outcome delivered?” 0Y 30M 70N
• “Is Enhanced Cx too expensive for for the outcome delivered?” 0Y 45M 55N
• “Is Cx too poorly defined in scope to be properly implemented?” 50Y 0M 50N
• “Are there too few qualified CxA?” 50Y 30M 20N
• “There is no uniform certification program” 70Y 20M 10N
• “Contractors don't understand Cx and as a result overcharge.” 60Y 25M 15N
• “Costs are not standardized (all over the map).” 80Y 15M 5N
• “Cx is the only way to ensure HVAC, lighting and other energy systems' installation are operating properly.” 70Y 20M 10N
• “Cx improves project quality.” 95Y 4M 1N
• “Cx reduces the liability of the design/construction team.” 50Y 30M 20N
• “Cx saves the client more money than it costs to perform.” 70Y 25M 5N

”The M&V point is the most important LEED credit with regard to reducing the carbon footprint of a facility. The second most important point is enhanced commissioning.” The justification for this is that you can't improve what you don't track (M&V), and that the enhanced Cx credit requires that the CxA train the owner about how the building is to function. Comments from a CxA on the panel indicated he has found hundreds of overrides in retrocommissioning projects that are the result of a facility manager not understanding how their systems operate.

The other major discussion on this topic revolved around the fact that there's wide variability in the scope when all this is asked for in the RFP is to provide LEED fundamental/enhanced Cx services. Fundamental Cx was seen by commenters to be insufficient, as you're really only asking the CxA to provide the 'middle' of the services. They're brought in too late (no substantial design review) and leave too early (insufficient training and verification).

LEED Risk Management: Crossing the Model/Reality Chasm

or

What happens if I've already jumped in?

This post began as a comment by Mitchell Swann of MDCSystems. "A question that continues to rumble thru my head is how does the owner's 'actions' related to operations and maintenance factor in to the potential for disputes and damages?".

This brings to mind two issues. While participating in a seminar a few months back the esteemed counsel sitting on the panel surmised that all litigation related to sustainable design and construction would be prosecuted using the same basic claims that exist today: delays ("That LEED certification didn't come through before my incentive options ran out!"), errors & ommissions ("You didn't get me my plaque"), negligence ("How high was that standard of care bar in 2002?"), etc. It seems to me that most of the time these issues will sort themselves out fairly and in much the same fashion as any other claim against an architect or designer. If the architect makes a reasonable effort to earn LEED certification making reasonable assumptions about how to proceed, and avoided making any boneheaded statements about their abilities in the field of sustainable design (I forgot to include misrepresentation in the list of claims above), then the law should smile favorably upon them even if something goes awry.

What interests me is what Mitchell raises above: What is really happening when you have a semi-official document that says you give a client a building whose design outperforms an ASHRAE 90.1 baseline by 25%. Does the client have any right to claim damages if the building underperforms in real life? The ASHRAE standard is not designed to cover all loads. Does the client forfeit any claims if he does not operate the building within the parameters of the design assumptions?

What can we do today to mitigate the issue? Not make any claims? This will be unavoidable problem whenever a school or municipality sets an energy benchmark for a project - see North Carolina's here requiring you to beat ASHRAE by 30% here. Are you just not going to take any of those kinds of projects? Good luck lasting five years...

It wouldn't be a fun conversation, but you could ask for a clause exempting you from any damages arising from the owner's operation of the building straying from set design assumptions. Perhaps a global warming clause is in order as well? That's bound to affect your cooling loads!

With an emerging (and proper) emphasis on tracking and more importantly reporting building performance, the real estate market will soon begin to value relative utility performance into leasing and development cost models. How this issue of designer's assumptions vs. owner operations is resolved will have real economic consequences. It is a looming problem that is not easily resolved, but a delay before it matters may be the one silver lining in having a market that undervalues the benefits energy efficiency. Being a blogger, I'm in the fortunate position to simply raise the question and ask the masses to decide on an answer... Please share your thoughts by leaving a comment!

Fun with Disclaimers

Guess what? I'm not a lawyer, and none of anything I've ever said or written or will write about should be construed by you, or your family, or your small to medium sized pets to be legal advice. Your large size pets may construe as they may, but that does not make it any more accurate.

Energy Modeling Further Demystified

Building on the previous post on energy modeling, there is another introduction to the process posted over at BuildingGreen called "Understanding the Energy Modeling Process: Simulation Literacy 101". Great read for beginners such as myself.

I found out about the above article thanks to Suzanne O'Leary of ThinkDwell--a company that designs homes making the occupants absurdly and a bit creepily happy according to the picture on their homepage. Suzanne has started what is sure to become a very helpful forum on energy modeling issues called EnergyModeler.com. The site is brand new and will need to develop an audience (that's you!) before it really provides a good base of info, but RealLifeLEED supports any and all online communities that could make sustainable design simpler for everyone. Check it out now!

New EAc1 Compliance Path: No Modeling Required

RealLifeLEED learned the hard way (from people I'm supposedly teaching about the LEED AP exam) that the USGBC has added another prescriptive compliance path for EAc1, Optimize Energy Performance, that can earn 2-5 points, thus allowing you to comply with the relatively new 2 point prerequisite initiated in June 2007.M

The Basics

If your project isn't a health care, warehouse, or lab project and is under 100,000 gsf, you're able to use the Advanced Buildings Core Performance Guide to earn anywhere from 2-5 points based on the number of strategies you implement and the project type you have. Offices, schools, public assembly and retail projects are eligible for up to 5 points, while all others excluding the healthcare, warehouse, and lab projects can only earn 4. The guide is available for $95 from here, OR you can get a free, slightly edited version courtesy of Efficiency Vermont here!!! FYI - you'll need to email info@efficiencyvermont.com for the password. From what I can tell requirements for other regions are still contained in the guide, though Vermont folks are lucky enough to have all of their standards highlighted! Where the standards aren't listed there is a link to the AdvancedBuildings website with a password (in the VT edition) that earns you access to more reference materials.

Free is Good!

From what I can tell, much of this is similar to ASHRAE 90.1-2001 performance requirements, but I'm a blogger and as such have only really skimmed the requirements. Components of the guide align with other LEED points, and there are handy guides to help you see where these overlap. The main point here is that many projects will be able to earn a significant amount of EAc1 points without the need for frequently costly energy modeling services. To be clear, I certainly suggest using energy modeling, preferably early in the design process, but sometimes such detailed modeling required by other EAc1 options is not necessary.

I have yet to have any experience implementing this guide and would really appreciate to hear from those of you who have! Please leave a comment about your experiences!

Energy Modeling: Structure, Strengths and Loopholes

RealLifeLEED is (sadly) back from his glorious vacation, but is happy to continue bringing the best in obscure LEED resources to you hardcore in-the-trenches AP's. Today I'm letting you know about an interesting article written by PhD and ASHRAE Fellow Stephen Kavanaugh about the strengths and loopholes associated with energy modeling, specifically related to ASHRAE 90.1:

Rating High Performance Buildings: What Architects and Owners Should Know

This article brings up a good point about the ASHRAE model, specifically that it won't necessarily be a good representation of the actual energy use! Kavanaugh cites a study that found LEED building's modeled and actual energy use differed by an average of 62%!!! The small graph on the page indicates that it's a roughly 50/50 split between over and underestimations.

It's important to understand what is included in the energy model, and how you shouldn't guarantee the client anything about reduced electricity bills. Though the building is modeled to have low energy use, an owner with a penchant for ice-cold workspaces or a retailer who loves open front doors could ruin the best intentions of your designs.

I personally had little knowledge about what's included in the models until I took a VERY useful USGBC half-day workshop entitled "Understanding Energy Modeling in LEED for New Construction Projects". It was amazing to me how quickly you can use free modeling programs to setup a rough baseline building and play with different features and conservation measures to see where you stack up. The final model will need to be completed by someone who knows what they're doing, but early simulations can provide some interesting insights for amatuers.

Energy modeling problems or helpful hints? Please share your thoughts by leaving a comment!

Determining Occupancy: Residential Edition

My last post on determining occupancy for LEED projects did not discuss how to determine residential occupancy, an issue I've encountered recently.

Searching through the Credit Interpretation Rulings, I found a rather vague answer coughed up by the supreme court that is the CIR council (committee? emperor?) dated 2/14/2007:

Per the LEED NC v2.1 SSc4.2 ruling dated 12/9/2005, occupancy should be calculated using the number of bedrooms in the case of residential projects. Project teams should provide a narrative with calculations demonstrating how the total number of residential FTE occupants was calculated including indication of number of units, size of units (e.g. studio, one bedroom, two bedroom, etc.), and assumptions as to number of occupants per each size of unit.

So we base it on bedrooms... great! It would sure be nice to have actual guidance on how to transfer that into a hard number, but why make it that simple? Now we get into the sticky issue of what number to put to what bedroom count. Being lazy, I did not take the time to research average occupancy across the nation or anything like that. Instead I proposed the following:

Residential Occupancy Per Bedroom

• Studio/1 Bedroom - 1.5 occupants
• 2 Bedrooms - 2.5 occupants
• 3 Bedrooms - 3.5 occupants
• 4 Bedrooms - 4.5 occupants
• etc.

Being the smart guy or gal that you are, you've probably picked up on "the formula". I think it's a safe bet to assume that a one bedroom could equally be expected to be occupied by 1 or 2 people, so I split the difference and assume 1.5. For additional bedrooms, it's likely to be occupied by either kids or roommates, but doubtful it will be occupied by additional couples.

I'd like to be clear that this assumption has not gone off for review yet, and I'm not going to spend a few hundred dollars to answer the question beforehand... I think this argument is reasonable, and expect it to be accepted, but don't want you to stake a large quantity of money on the fact that I'm right. If you have used different assumptions that worked or tried this one and failed, PLEASE be sure to comment on your experience below. Thanks!

Determining Occupancy

So we need to know our occupancy for our nice LEED project... great. This question bothered me for a long time, especially since it affects so many credits. Then I realized you're basically supposed to make it up! Really though, the owner is supposed to supply you with the numbers, but how is he going to do that if they're not sure? If you're working a core and shell project that fits neatly into the groupings below, you can use the default occupancy numbers (in square feet/FTE) below. Most credits is defined as SSc4.2, SSc4.3, SSc4.4, EAc1, EQp1, EQc1, EQc2, EQc6, and who could forget, EQc7. See the LEED-CS reference guide (page 441) for more detail.

If you're not fitted nicely into one of those groups, you're on your own. I take the code occupancy count and break out the reasonably inferred FTE. If you have a restaurant, there are only going to be so many cooks in the kitchen, tables per waiter, a hostess, a bartender, and a manager. I would then subtract that number from the code occupancy to give me the transient loading, which would be added to the FTE number to determine peak loading. In a mixed-use project you would need to look at hours of operation - as peak loading for a movie theater is likely to be on a different schedule than peak loading for an office. See below for an example breakdown for SSc4.2, Bicycle Storage and Changing Rooms.

Am I wrong in my assumptions? TELL ME! Please use the comments to make this site more informative!