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!

Phenol-Formaldehyde: Go Ahead and Use It

I recently received a question about whether phenol-formaldehydes would void our attempt at achieving EQc4.4, Low-Emitting Materials, Composite Wood & Agrifiber Products.

LEED allows the use of phenol-formaldehydes!

Go ahead and use as much as you like. Technically, your composite products can have urea-formaldehydes too, as long as they occur naturally and aren't added.

Mark Piepkorn of BuildingGreen had the following (must be a member to access) to say on the subject:

While... phenolic-resin panels are made with binders that contain formaldehyde, they do not release as much of the toxic compound as panels made with urea-formaldehyde binders, and they qualify for use in the LEED Rating System's composite wood credit.

Certifying Multiple Buildings Together? Part 2

While Part 1 of this soon to be made-for-tv mini-series (I've got even money on actor Martin Donovan playing USGBC founding chairman Rick Fedrizzi) focused on money, today we're going to look at how your decision to certify buildings together or separately may affect your the time it takes you to complete the documentation. Unfortunately, that is going to require a little more learning about the three systems the AGMBC uses to organize multiple buildings projects.

Multiple Buildings Application Guide 101

I've been working on two large LEED projects that each contain multiple buildings. On one we decided to certify each building independently, on the other we're working on certifying a group of buildings under a single certification. In theory, the guide should be able to save us money (on certifications) and time (which is money). In practice I haven't noticed too many benefits to the recommendations in the guide. I'm going to point out where I've seen it help and parts I throw out the door.

View the "LEED-NC Application Guide for Multiple Buildings and On-Campus Building Projects(AGMBC)".

When discussing paperwork it's important to remember that the application guide is only a guide, and you can at your discretion flip between the requirements of the guide and those of a regular LEED-NC project. Page 6 of the AGMBC clearly states that "Credit requirement alternatives in this Application Guide may be used instead of the regular LEED-NC requirements, but are not mandatory as they may not apply in all situations."

The Systems

Certifying a Single Building in a Campus or Master Planned Development

This essentially allows you to include master plan elements that may be off-site in your documentation. On one of our projects, our stormwater is handled in a retention pond within the development, even though it's not technically on our "site". We've also accounted for shared parking garages and light trespass issues by including the larger site. The guidance here is almost universally helpful, as you can pretty much throw out any problems you previously had regarding shared amenities.

Certifying Multiple Buildings in One Phase of a Project

This path causes some problems. The goal here is to allow for shared site amenities as above, but there's also guidance about where you can average savings across buildings. The main problem here is that for many points each building must meet the requirements individually or ALL do not earn the point. I've tried this once and haven't been impressed with the results. Remember, you can always gain the bonuses of the first system for shared amenities and certify each building individually.

One development that we tried this on we lost the (EQc8.1) daylight credit due to one building while the rest had ample lighting. Another place you can have problems is (EQc4) Low-Emitting Materials credits. Here's a list of credits where one building missing the credit will void the entire project. Given the long list, I'm sure at least one will trip you up:

  • SSc1, Site Selection
  • SSc2, Development Density & Community Connectivity
  • SSc5.1, Site Development - Protect or Restore Habitat (Greenfield sites only)
  • EAp1, Fundamental Commissioning
  • EAp2, Minimum Energy Performance
  • EAp3, Fundamental Refrigerant Management
  • EAc3, Enhanced Commissioning
  • EAc4, Enhanced Refrigerant Management
  • EAc5, Measurement and Verification
  • EQp1, Minimum IAQ Performance
  • EQp2, Environmental Tobacco Smoke (ETS) Control
  • EQc1, Carbon Dioxide (CO2) Monitoring
  • EQc2, Increased Ventilation
  • EQc3, Construction IAQ Management Plan
  • EQc4, Low-Emitting Materials
  • EQc5, Indoor Chemical & Pollutant Source Control
  • EQc6: Controllability of Systems
  • EQc7, Thermal Comfort
  • EQc8, Daylight and Views

Conversely, the averaging of some credits can allow single buildings that may not achieve a credit to comply within the group. This is mostly where you would expect (energy and water use, shared site amenities like bike racks and showers, parking requirements, MR3-7 credits, etc.) so I won't waste your time with a full list. There is guidance on how to weight each calculation across buildings as well. The biggest savings will likely come from not needing showers (for bikers) in all buildings.

Certifying Similar Buildings to a Set of Sustainable Standards

Think design "prototypes"... architect kryptonite! This makes a lot of sense if you're a Wachovia or Starbucks and want to build a bunch of cookie-cutter buildings. You're allowed to designate a set of "prototype" credits that will be applied equally to all buildings. The first building's credits will be carefully scrutinized, but then you don't have fill out all the paperwork for subsequent buildings on the prototype credits. Sounds great, but then you find out they will audit a few of these credits each time, so you still need to collect all those materials invoices!

I haven't worked on a project like this yet, but if the buildings are really similar, you can likely save a good deal of time. If the floor plan is the same you can avoid daylight and views calcs, which are some of the most time-consuming. The more design freedom you have the less sense this makes.

What to do?

Ultimately, any time you're working in one of the three systems you're going to need the application guide. My limited experience with certifying multiple buildings together has left me recommending certifying them independently, but sometimes the certification cost savings can't be ignored. Either way, you need be clear about how the "reasonable project boundary" is going to be setup with civil engineers, landscapers, the architect, and whoever's designing the site lighting.

It seems silly, but be aware 1 certification = 1 plaque, regardless of how many buildings are involved. USGBC won't fork up another one, even if you try to buy them off. If the client is interested in marketing a LEED facility, this might be an issue!

As always, please leave your experiences with certifying multiple buildings in the comments section. I'm sure someone will point out a few mistakes by the end of the week, so check back later for corrections!

Where Do Primers Fit in the VOC Limits?

I was just asked today about what the VOC limit is for primers to help achieve EQc4.2, Low-Emitting Materials, Paints & Coatings. A CIR ruling (for NC 2.0/2.1, none listed for NC 2.2) states the following: 3/14/2003 - Ruling The Green Seal Environmental Standard for Paint (GS-11) is the standard on which achievement of this credit is based. All paints used on the project must meet these standards to achieve this credit. According to Green Seal, primer is classified as a topcoat for purposes of this standard and must comply with the requirements as well. So... the primer definitely must meet the standard. The question now is whether it's flat (50 g/l) or non-flat (150 g/l). I have a hard time believing that it would be non-flat, but then again, primers are never really listed either way. I tend to err on the side of durability, not LEED, and I could definitely see where additional VOC's (which sort of serves as a proxy for performance) would help improve adhesion. After reading through a PPG created guide spec, I get the impression that these primers qualify as non-flat finishes. They repeatedly exhibit awareness of the different requirements between flat and non-flat paints, but in most cases the primer (including multiple series and substrates) is between 50-150 grams/liter. See page 6 for the spec, page 23 for LEED COMPLIANT OPTIONS. Note, for gyp board and other surfaces they often offer a zero voc option... while potentially expensive, there would be no doubt about compliance...


Primers must meet the limit for NON-FLAT paint with a 150 g/l VOC max.

Alert reader Josh Greenfield once again has pointed out something I missed. He was smart enough to search through the latest LEED-NC Reference Guide Errata Sheet (page 11), where it definitively states that primers are to be considered non-flat paints.

If I had been so smart this would have been a much shorter post. Due to the corrections some of the unecessary portions of the original post has been removed.

Commingled Trash and Recyclables

So the building's finished, you're putting together all of the documentation, and you notice that somebody forgot to include an area for storing and collecting recyclables! A classic "oh s#&*" moment... This is a pretty serious problem, as since this space is part of a prerequisite, all of your hopes for LEED certification are shot, right?
Mixed waste recycling to the rescue!!!

Way to go WM!

Lucky for you, there are companies out there that will take everything in a waste bin, from food to paper to aluminum and glass. They then separate it off-site, and recycle everything they can. More importantly, a CIR dated 12/15/06 has indicated that this practice is acceptable. The ultimate result is that you can achieve this credit without incorporating a storage and collection facility on-site. Though it doesn't expressly say so in the CIR, I would imagine you should provide some sort of documentation that this service is being used.
There's good reason for this acceptance, as the system is fool proof... No need to separate bins, have someone come pick up the recyclables, etc. You just throw everything away and the magic machines take care of the rest. Not to say there aren't any problems with the system, but basic concept is sound. Of course, you could always just build a shed outside, but where's the fun in that.

Timekillers - LEED-CS EQc8.2 - Daylight and Views

Are you working on a spec office building and committed to providing LEED documentation? You may not realize you've essentially committed to designing a tenant upfit for free! LEED-CS credit EQ 8.2, Daylight and Views, Views for 90% of Spaces requires the development of "a feasible tenant layout(s) per the default occupancy counts (or some other justifiable occupancy count) that can be used in the analysis of the credit." Being familiar with the LEED-NC version of this credit, I overlooked this when quickly browsing the CS reference guide and putting together the documentation for a recent project. As you can imagine, putting this together in both plan and section can add significantly to the hours required to complete the work, so consider that when calculating fees and schedules. On the bright side, if you get the job for the upfit design you're in pretty good shape...

LEED-CS SSc4.3 Credit Template is Wrong!

The credit template for Sustainable Sites credit 4.3, Alternative Transportation, Low-Emitting and Fuel-Efficient Vehicles is messed up for option two.

Bad Template! No soup for you!

Note: 937 spaces would only require 47 preferred parking spaces, but we like priuses so much we decided to give them two more places to park...

It should be 5% of total on-site parking instead of the 3% listed. Note, you will need to input the correct number of parking spaces (in the second box... and the project) regardless of what the "Required" box says. Don't forget to always round up (i.e. 4.1 spaces = 5 spaces). Also, the similar LEED-NC template is correct. It is only the LEED-CS template that has the error. HUMBLE PIE ALERT!!! CORRECTION BELOW Alert reader Josh Greenfield pointed out some inconsistencies between my original post (above) and the truth. I'm sure this is the first time of many... please feel free to call me out on any post in the comments section!

Really it boils down the the template being even more wrong than I realized. The "Option 2" that I referenced is really Option 1 in the LEED-CS reference guide. Option 1 on the credit template references a compliance path that doesn't even exist for LEED-CS! In the LEED-CS reference guide:

  • Option 1 - preferred parking for 5% of parking spots based on parking capacity
  • Option 2 - alternative fueling stations for 3% of parking spots based on parking capacity

The credit template says:

  • Option 1 - I'm guessing they just copied from the NC version, requiring fuel efficient vehicles based on 3% FTE. This isn't even an option for CS!
  • Option 2 - preferred parking for 3% of total parking on the site.

I've only submitted for preferred parking, but the review comments I received indicate that the refernce guide requirements, not the credit template requirements, are what need to be followed. I'm guessing if you want to submit for the real Option 2 (alternative fueling stations) you would need to either fill everything into the alternative compliance section or steal the LEED-NC credit template from another project and save it to the supporting documentation section? Leave a comment if you've encountered this before...