Tuesday, February 21, 2012

Energy Upgrade California and EnergyPro, part 2

I followed up on what I learned in the January 20 workshop by contacting a fellow Santa Cruz Construction Guild member, General Contractor Scott Milrod. Scott is very involved these days with home energy upgrade projects, and is qualified as a participating contractor in the EUC rebate program. It turned out that Scott had already started on a demonstration project with Ecology Action. The EUC rebates come in two “flavors”:

  • Basic – a $1,000. rebate given for installation of a prescriptive package of energy-efficiency upgrades.
  • Advanced – a $1,000 – 4,000 performance-based rebate. The amount awarded is determined by the amount of improvement (reduction in household energy cost). The contractor and homeowner can choose from a wide variety of improvement measures. Choices are customized to fit the individual situation.

The required “as-built” testing and EnergyPro modeling were complete, so the work remaining to be completed before submitting a “pre-installation” application for a rebate was the dreaded paperwork. That’s where I was able to get involved and help out, while learning about the process. Actually, “paperwork” is an outdated term, since all of the required forms can be completed and submitted online. This “paperless” process is available through the EUC website, which was set up by the CEC to be a “one-stop shop for energy upgrades”, including rebate and incentive programs all over the state. For our demonstration project, the application process involved completing and submitting the following:

  1. An on-line, guided application form.
  2. At least one year’s worth of energy use/cost data. In this case that meant natural gas and electricity use data from PG&E.
  3. An EnergyPro model of the house, first with the existing conditions, then with the proposed improvements
  4. The contractor’s proposal to the homeowner
  5. A test measurements form, created by PG&E, for recording safety-related test data, such as interior CO emissions from gas appliances.
  6. An Excel worksheet containing much of the same data as the online application.
  7. A copy of an authorization form, signed by the homeowner, giving EUC permission to use the energy data in the rebate application process.
All of this was completed a couple of days ago. Now we wait for the application to be reviewed. When that happens, I’ll give you all an update. Another future topic that may be of interest is a discussion of the kinds of home energy upgrade products and methods that are available these days. Energy costs are a concern to everyone these days, so it’s important for designers and contractors to be able to address clients’ needs in this area.

Energy Upgrade California and EnergyPro, part 1

On January 20, I attended the morning session of an EnergyPro / Energy Upgrade California workshop. I have used EnergyPro for many years to do T24 compliance calculations and documentation for building permit submittals, so I was interested in learning about new uses for a very good software program. The workshop explained how EnergyPro can be used to analyze the benefits of upgrades to home energy-efficiency measures; things like adding insulation, fixing leaky heating ducts and replacing old furnaces and windows. The Energy Upgrade California program offers rebates to homeowners for qualifying improvements. Requirements for documenting such improvements are fairly technical - that's where EnergyPro can help. The software includes extensive capabilities to model a wide range of energy-efficiency improvements, and the ability to generate reports for documentation.

The workshop did not assume any prior knowledge of EnergyPro, so the morning session was spent in a basic introduction to the workings of the software. It seemed to me that about one-third of the attendees were already familiar with EnergyPro, so there was not too much new information for us. Of interest to me was instruction on the use of some sections of the software I'm less familiar with, including detailed modeling of HVAC system features. For my usual T24 compliance work, it's not necessary to go into such detail in that area.

I was sorry that I could not stay for the afternoon workshop session, which got into the actual production of Home Energy Assessment reports, and others required for the Energy Upgrade California rebate program. Energy analysts for the rebate program are required to possess knowledge, which I currently lack, of various testing procedures to show before/after improvements in energy efficiency. However, the preparation of a Home Energy Assessment report can be a very effective sales and marketing tool in itself. The report shows homeowners how much money they can save on their energy bills by installing specific energy-saving measures. I plan to get into that area, in partnership with contractors equipped to do the necessary testing.

Saturday, July 23, 2011

Conventional Construction: Selecting framing lumber

Wood is the most conventional of materials, and lumber is the wood used in conventional construction. Not just any lumber, though – as noted previously, lumber must be standardized and pre-approved in several ways. Also, allowable size and spacing of framing members are prescribed. The building code (CBC) simplifies the selection of conventional structural lumber by providing tables, organized by intended use. One thing you'll notice about the tables is that only a few wood species and sizes are included. For other choices, an online selection calculator from the American Wood Council is available here. If you use this tool, be sure to verify your selection with your inspector or building official.

The image at left shows the title of the first of two tables for selection of floor joists. The difference between the two tables is enclosed in parentheses below the title: (Residential sleeping areas, live load = 30psf…). The other table is for: (Residential living areas, live load = 40psf…). This split table is a change from the previous code; using different live load (mainly people and furniture) values for living and sleeping areas.

Just below the title is the header section of the table:
The header shows several important variables. The first is dead load, which is the weight of installed materials supported by the joists. The old code had a table giving weights of many different materials, but there’s really only one common situation that might call for using a dead load = 20psf – that’s heavy flooring like mortar-set tile. Another situation where using 20ps might be a good idea is if you know the room is going to be used for something like weight-lifting. In the following example, we'll use only the 10psf side of the table.

To use the table, start with the desired span, then move out to the edges to find size, wood species and spacing. For example, say you have a 14’-0” span. On the left half of the table (dead load = 10psf), find the span numbers closest to but not less than 14’-0”. For simplicity, we’ll stick to the most common (in Santa Cruz) wood species, Douglas fir (D.F.). Grade #3 is not commonly available, so we’ll ignore that also.
As a designer, I would conclude that the three best conventional size/grade/spacing options are:
2x8 #2 @ 16” (rectangles added to highlight choices)

2x8 SS @ 19.2”

2x10 #2 @ 24”

At this point, you can plug these three into your estimator software along with current prices and go with the most cost-effective choice (note also that, for the contractor, current prices and/or labor costs might point to a choice other than these three). Cost aside, sometimes there are design reasons for preferring one size or spacing over another, but that’s a topic for another time.

Tuesday, July 12, 2011

Conventional Construction: When Does It Become Unconventional?

Designers and contractors wishing to keep projects conventional obviously must avoid the unconventional. That's one of the main objectives of the pre-proposal feasibility research. It’s no fun explaining to clients the need for expensive structural analysis after they agreed to a proposal based only on conventional design (of course, proposals that don’t allow for unexpected discoveries later on should also be avoided).

Neither is it any fun for a contractor to make what seems like a minor client-requested design change in the field, only to be told by the Building Inspector that the project must now be engineered. Something about that minor change caused the project to cross an invisible line into the unconventional zone.

It can be a very fine line indeed between conventional and unconventional, so a thorough understanding of the determining factors is important. Previous posts have discussed a few of the general factors. Also, some situations are more perilous than others, so we'll try to cover as many of those as possible. 'Dividing line' situations fall into three categories: materials, methods and conditions.

Thursday, July 7, 2011

Conventional Construction: One More Term

I should mention one other important term - approved. It’s a term you often hear, but it has many different meanings, depending on what’s being approved and who’s doing the approving. Our favorite, as designers and builders, is the one that appears on that long-awaited letter from the Planning Department – ‘all agencies have approved your building permit application’. Two slightly different meanings are also important in project design and construction.

Pre-approved

A material or method not normally considered conventional may be used prescriptively (without further analysis) if it is pre-approved. The pre-approval process involves extensive testing by a testing lab, which must itself be pre-approved by the ICC. The lab then prepares a report describing the approved uses of the product tested. A familiar example of a testing lab is the Underwriters Laboratory (UL). For conventional construction, the ICC Evaluation Service (ES) is probably the most important. Metal framing connectors, engineered wood products and gravity retaining wall systems are examples of products that are pre-engineered and pre-approved.

Reviewed and approved

Everything on a set of plans and everything built from those plans must be reviewed and approved by one or more representatives of the local authority. Also, despite the complexity of building codes, local regulations and all the other hoops that must be jumped through to get a building permit, there are still gray areas not clearly defined and/or understood. When these situations arise, the local Building Plans Examiner, Building Official or Building Inspector must review the proposed solution and decide whether or not to approve it.

For the project designer, the big hurdle is getting that approval letter so the contractor can begin work. For the contractor, there’s always the fear that the Building Inspector will look at your ‘conventional’ work and say ‘you can’t do that’ or 'that's not on the plans' - and his word is the final word. However, a thorough understanding of the rules will often allow a designer or contractor to convince the inspector to see things your way. Don’t relax yet, though – especially if you get a different inspector for the next visit (when scheduling an inspection, always make sure your regular inspector is not sick or on vacation). The project team can’t really breathe a collective sigh of relief until that final permit sign-off.

Friday, June 17, 2011

Conventional Construction: Related terms

Before moving on to a discussion of unconventional materials/methods, a side trip is needed here to define a couple of terms that relate to but are not quite the same as conventional. The two are standardized and prescriptive.

Standardized

The first step toward use of a material or method in conventional construction is standardization. When you buy a 2x4 stud at the lumber yard, it has a stamp proving that it meets certain standards of suitability for the intended use. Common standards for lumber include wood species, quality grade, dimensions, and others. I don't plan on devoting too much blog space to discussion of standards - that's a whole different blog. For the inquiring mind, the conventional construction book published by the ICC does a pretty thorough job on standards.

Application of conventional construction provisions in modern building codes requires use of standardized materials, which is a change from the original definition of conventional. This is frequently an issue in Santa Cruz County, where many property owners would like to use on-site resources such as trees in proposed construction. In the old days, you might chop down a few trees, hand-saw some lumber and build yourself a house. It doesn't work that way anymore in this country. Native, site-prepared logs, lumber and/or heavy timber may be suitable for exterior construction of open structures like porches and trellises (if approved by building officials), but not allowed in conventional construction (or structural analysis) of a habitable building because the wood hasn’t been tested and standardized. Unless its physical properties are known, there’s no way to know where and how it can be safely used. On-site testing may be possible, but the extra time and expense means that such materials are not conventional.

Prescriptive

Once a building component has been standardized, guidelines for its use can be published in a building code. These guidelines are prescriptive; giving designers and builders permission to use certain components in certain situations. For instance, to use that standardized 2x4 stud in framing a wall, building codes give us prescriptive limits on maximum height and spacing. Designers use those limits in drawing plans; builders use them in construction; plans examiners and building inspectors use them to verify construction quality. Prescriptive guidelines are also conventional, in the sense that we can use them in building structural design without further analysis.

Monday, June 6, 2011

Conventional Construction: What is it good for?

Current building codes describe three methods for structural design of buildings:

1. Conventional construction is the oldest, simplest design system and the main focus of this series. It is often adequate for structural design of small projects, but limited to light-frame, one-or-two-story wood buildings. The utility of conventional construction can be extended by use of:

2. Pre-engineered components and systems. Many of these are described in building codes, such as conventional concrete perimeter foundation systems. Some pre-engineered components are found in manufacturers' catalogs, such as metal framing connectors.

3. Structural analysis. Performed, in most cases, by a professional structural engineer, structural engineering analysis is outside the scope of this discussion. Many design situations require structural analysis, and designers have the option to employ it for any design. If there’s a choice, however, conventional solutions are usually more cost-effective. One of the goals of this discussion will be to find and discuss those situations where the designer and builder have conventional options which might reduce the cost of a project without compromising quality.

Successful application of conventional construction requires the builder or designer to know when you can't use it, so it might be easier to start with a discussion of what it’s not good for. One category of situations where conventional construction often won't work is with un-conventional materials and methods. That’s our subject for next time.