Archive Of The Category ‘air sealing‘

 
 

ZNE guidance for CA architects (& others!)

AIA ZNE Primer cover image

AIA ZNE Primer cover image

The American Institute of Architects California Council recently published the Zero Net Energy Primer. I had the privilege of developing the Primer for them under a contract with PG&E. The Primer (if I do say so myself) is a handsome, concise, and accessible guide — a mere 24 pages, including lots of pictures of ZNE homes of all flavors (small, large, single- and multifamily, luxury and affordable). The AIACC’s goal in publishing the document is to ease the task facing California architects with the roll-out of the State’s 2019 energy code (“Title 24”). The new code will go into effect January 1, 2020 and — while it doesn’t quite get us to ZNE — represents a significant advance in residential energy performance, and the first time that homes will be required to install renewable energy systems. (Of course, there will be byes for projects where it’s simply not feasible to install them.) The Primer will, I hope, help architects get a handle on the ZNE requirements ahead of the looming 2020 deadline.

Kudos and many thanks to designer Debra Turner for the engaging design, and to architect Steven Lee for his terrific illustrations.

 

Obsessed with roofs

Newburyport, MA, ZNE home -- Steven Baczek, architect

Newburyport, MA, ZNE home — Steven Baczek, architect

A recent email thread involving a group working on a video about ZNE design prompted me to raise one of my favorite subjects. Say I, “Will you talk about the critical importance of roof design?” Queried Steve Mann in reply, “Do you have something more specific in mind?”

I’m so glad he asked! It gave me an opportunity to vent (pun intended) about this topic, which I find is absent from far too many conversations about ZNE home design. Here’s what rolled off the keyboard.

  1. You need to know your (approximate) energy loads early on, so that you have an idea how much solar-appropriate roof area you’re going to need. [That requires a calculation — for example, using NREL’s PVWatts.]
  2. You need to factor in code-required clearances around the solar array, and depending on the size/shape/proportions of the roof plane(s) in question, those margins can eat up a hefty fraction of the total area(s).
  3. You need to NOT have vent stacks and other obstructions interrupt that oh-so-critical PV roof area.
  4. All of the above — to those who are realistic and paying attention — dictate the simplest practicable roof form.
  5. The less attention you pay to the above considerations, the harder you will have to work on the enclosure and other efficiency measures to achieve ZNE — e.g., adding in more and more expensive measures, such as imported windows.
  6. Conversely, the MORE attention you pay to (simplifying) the roof, the more flexibility you will have with other building features.
  7. The simpler the roof:
    • the more money you’ll have for other features;
    • the less it will cost to develop elaborate architectural details to ensure thermal & moisture integrity;
    • the easier it will be to air-seal and insulate the whole building;
    • the more likely that the air-sealing & insulation will be done well;
    • the better the building will perform; and
    • the less the risk of later thermal, moisture, condensation, and rot problems.

So a simple roof is an all-around win: save money, improve thermal and moisture performance, get to ZNE more easily.

It’s time that we rekindle a time-tested aesthetic, one that finds beauty in simple, elegant, well-proportioned forms, robust materials, and quality of craft. One of my favorite architects who has complete mastery of this approach is Steve Baczek. Not coincidentally, Steve spent many years working with Joe Lstiburek and Betsy Pettit at Building Science Corporation — he’s also thoroughly conversant with building science. Take a look at Steve’s portfolio for inspiration!

Air Sealing Doesn’t Just Happen

One of the biggest challenges in a high-performance building project is getting the air sealing right … and it doesn’t JUST HAPPEN. It has to be carefully designed and detailed in the construction documents. A number of architecture firms are doing a very good job at this, one outstanding example being Coldham & Hartman Architects in the Northeast US.

The partners at C&H have been kind enough to allow us to post one of their air sealing drawings so that y’all can use it as a “CASE” study! (That’s pronounced with a light southern drawl, as rendered by Dennis Creech at Southface Energy Institute, and as Dennis explains, that stands for “Copy And Steal Everything.”)

Click here for the whole drawing: C+H A5.2 Wall Section AS

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