Abstract:
Home builders can offset cost premiums for going green by following these best practices from the NAHB Research Center.
Publication Date:
Sun, 2010-02-28 18:00
Article Image:
| Optimized framing techniques can help offset the cost of building green |
| By taking simple steps, like using optimized framing techniques and efficient mechanical duct runs, builders can offset the cost premium for going green. Photo: www.platinumleedhome.com |
Green home building and third-party certification have made significant gains in the residential construction industry over the last few years. In some locations, the green segment of the market has thrived while housing sales in general have slumped.
However, achieving green does not come without added costs. Regardless of the green-building rating system used, there are three categories of costs that come with building green: construction costs, verification costs and certification fees. These additional costs may deter builders from considering building a green-certified home. But there are ways to significantly reduce or eliminate additional construction costs — and even reduce typical construction and operational costs — by examining some key areas of the construction process, eliminating any potential labor and materials waste and increasing efficiency on site.
Through the NAHB Research Center’s National Green Building Certification Program, we’ve had an opportunity to hear from a number of builders and industry consultants about how they have gone green and saved money in the process. Here are some baseline considerations.
How do the homes you build now stack up against the green rating system you plan to follow for certification? You may be closer than you think to achieving an entry-level green certification in your preferred program.
For certification using the NAHB National Green Building Standard, make the free online Green Scoring Tool [1] your first stop. The tool will score your home against the four potential levels of certification (Bronze, Silver, Gold and Emerald) based on the practices you currently use, and will identify additional practices that will improve your project’s environmental performance. Many builders have found themselves within five or 10 points of Bronze, which could be achieved with a very low- or no-cost change in one or two products they were using.
If you are currently using stick-built construction to frame your homes, you may want to consider using panels or trusses. These techniques are labor- and resource-efficient, resulting in less on-site waste and potentially lower labor and material costs. As a bonus, fabricated systems often create greater thermal efficiency over stick frames. Wall panelization also results in more precision in the construction process, which can make it easier to implement and control other construction changes, such as a transition from 2x4 to 2x6 construction. Many green rating systems, including the National Green Building Standard, also award points for use of panels and trusses, providing a win-win for your budget and green-certified projects.
If you choose to frame on site, there are several optimum value engineering techniques that can save on material and labor costs, while generating green points at the same time. Look into options such as:
- Ladder blocking — Uses less wood; makes more room for insulation; gets green points
- Two-stud corners — At least one less stud at each corner; allows for more fully insulated corner; gets green points
- Switch from 2x4 @ 16 inches on center to 2x6 @ 24 o.c. — May result in small cost increase initially, but gets a lot of green bang for your buck
Another simple method for cutting costs is to develop a cut list — a set of cutting instructions and guidelines for your field crew that ensures the material you purchased for a particular application is used for the intended purpose. For example, a job might require two 8-foot-long, 2x10-inch headers and the purchasing manager was able to save some money by ordering one 16-foot-long, 2x10-inch piece of lumber that could be cut in half and used without any waste. Without a cut list, the field crew will likely pick up the first 2x10 material they see — maybe two 12-foot-long 2x10s — and cut it to fit the immediate need, which, in this case, would result in 4 feet cut off each piece and thrown away as waste.
Optimizing duct runs and centrally locating the mechanical room can result in material cost savings and increased energy efficiency. Be sure not to have more ducts or longer duct runs than are needed in any part of the house. In addition, make sure that your HVAC contractor is using Manual J or D calculations to design the most efficient placement of ducts.
Using a central return also reduces material costs and, in combination with transfer grilles in spaces like bedrooms where doors may be frequently closed, is a simple system that can provide adequate circulation and cost savings to both you and your buyer.
Placing all HVAC equipment, including ducts, in conditioned space within the home is also a smart move. In addition to creating significant energy savings and earning green points, this practice may also allow you to spec smaller, less-expensive HVAC equipment and limit or eliminate the need for additional insulation for the duct system.
If you are already building energy-efficient homes or plan to increase the energy efficiency of your plans as you embark on green construction, don’t be surprised if the HVAC equipment you are currently using is larger and more costly than you need. A tighter, more efficient building envelope significantly reduces the HVAC burden for the home, as less conditioned air is leaking out and less unwanted unconditioned air from outside is leaking in.
When designing the plumbing system, look for efficiencies in both labor and material. Consider employing a stacked approach, where rooms that require plumbing runs are aligned so that less piping is required. In addition, consider PEX piping over more traditional materials. While PEX comes with a slight first-cost premium, it does not require pipe cuts or joints, reducing material and labor costs. Finally, consider centrally locating your water heater to reduce the length of piping runs.
In many respects, a green certification program can also help boost the overall quality of the homes you build, and the residual customer satisfaction. Regardless of the material or design, having an explicit underlying quality assurance plan in place is always going to be a cost-saver. Quality assurance takes a holistic look at practices throughout your business and helps you determine where there are inefficiencies and how you can remedy them.
Consider the cost of a callback. How much does it really cost your company to call a tradesperson back to a jobsite to repair or replace something? Couldn’t you or your superintendent be doing something that would generate revenue, rather than attending to callbacks? And what about getting a red tag from a building inspector? Doesn’t that waste valuable time and money for your company? Wouldn’t it save you precious resources to eliminate callbacks and red tags altogether by making sure things are done right the first time, every time?
While there are numerous ways to increase the quality assurance quotient on your jobsites, one prime area to focus on is the scheduling of trades and creating job-ready conditions for each crew that comes to the site. If the work of each trade crew is not done correctly and in the right order, it results in numerous dry runs and re-dos — all of which correlate to real costs. Sit down with your trade crew supervisors to determine what needs to be done, and with what precision/tolerance, before their crew can completely do its job. Then be sure to write what constitutes a complete job, ready to turn over to the next crew, in the scope of work you create for each trade group. These simple steps can shave days off the production schedule.
For more information on National Green Building Certification and scoring a home to the National Green Building Standard, visit www.NAHBGreen.org [2].
