New construction has stolen the sustainability spotlight so far. However, of the estimated 4.5 million commercial properties in the U.S., new construction comprises only a small percentage of the total. This means that there’s more potential for meaningful environmental impact if commercial buildings that have been standing for 20, 30, 40 years or longer retrofit to more efficient products and systems.
There has been so much emphasis on sustainable products in new construction that professionals may mistakenly think it’s too late or not worthwhile to pursue sustainability with existing buildings. Property owners are now realizing that the green building movement applies to existing buildings, too, and many are beginning to do something to improve the efficiencies of these properties.
Older buildings have much to gain by being more sustainable, yet achieving sustainability targets differs in key respects from new construction. The U.S. Green Building Council (USGBC) has recognized these differences with its formal adoption of changes to the LEED® for Existing Buildings (EB) rating system to better represent and accommodate their sustainable interests. The reference guide and submittal templates for the updated LEED-EB are currently under development and are expected to be available in June 2008.
Table 1
The New and Improved LEED-EB
LEED-EB, now called LEED-EB: Operations and Maintenance (O&M), addresses buildings that are already occupied and operational, whereas LEED-NC is limited to new design and construction. LEED-EB: O&M also puts more focus on operating and managing buildings more efficiently. The categories on which a building is rated are similar in both. These include sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor environmental quality and innovation.LEED-EB: O&M certification is an ongoing process that requires building improvement, maintenance and education. Each “point” must be inspected quarterly to see how building occupancy, energy demand and education have been carried out over time. Buildings with a LEED-EB: O&M rating are required to re-certify at least every five years to maintain their certification status, but can re-certify as often as yearly.
Some of the features of the revamped rating system include fewer prerequisites (reduced from 13 to 8); whole-building cleaning and maintenance issues, including chemical use; recycling programs; exterior maintenance programs; system upgrades; updated reference standards; more rewards for measured environmental performance; and expanded sections on water efficiency, energy performance, building commissioning and green cleaning.
There are now 50% more points for energy efficiency and new credits for energy best practices, including auditing, existing building commissioning and ongoing commissioning. And water efficiency now has double the number of points available, including new credits for metering and cooling tower water efficiency.
LEED-EB: O&M covers water efficiency with two prerequisites that must be met by all buildings seeking certification, followed by three optional credits. The first prerequisite focuses on reducing fixture potable water usage to a level equal to or below the building’s water usage baseline. The baseline is established at 120% of the total water usage if all of the building’s fixtures meet the Energy Policy Act of 1992 (EPAct) fixture performance requirements (see Table 1).
This can be demonstrated with separate metering for each water-using application (fixture use, process use, irrigation and other uses) or by calculations indicating the water-use reduction achievements. At least one meter for the overall building water use is required. Metering for cooling towers and other process water uses are encouraged but not required.
To better understand the calculation method, let’s assume we have a commercial building with two restrooms. The men’s restroom has two urinals and two water closets. The women’s restroom has four water closets. Each restroom has two sinks with a manual faucet. There are 50 men and 50 women occupying the building during office hours.
Create a spreadsheet listing each water-using fixture and the frequency of use data. Frequency of use data includes number of female and male daily uses, duration of use and water volume use. There are no set criteria for determining daily use or duration of use, so these items can be estimated based on the project’s program requirements.
These values are used to calculate the total potable water used for each fixture type and gender. Use EPAct fixture flow rates for the baseline case. Then calculate 120% of that total (see Table 2 on page 38). Graywater or rainwater harvest volumes must not be included in baseline calculations.
In our example, the EPAct 100% usage is calculated to 157,950 gallons of water used annually, and the building baseline is calculated at 189,540 gallons of water used annually. This baseline is referenced in further Water Efficiency (WE) 3.1 and 3.2 credits.
Water-efficient plumbing technologies can be used to go beyond the prerequisites and contribute to achieving WE 2.2 Innovative Wastewater Technology. This strives to reduce generation of wastewater and potable water demand, while increasing the local aquifer recharge. This often is the most challenging credit in the Water Efficiency section. To achieve this, one option is reducing potable water use for building sewage conveyance by 50% through the use of water-efficient fixtures (such as water closets and urinals) or non-potable water (such as captured rainwater, recycled graywater, and on-site or municipally treated wastewater).
WE 3.1 and 3.2 Water Use Reduction credit can maximize fixture potable water efficiency within buildings by reducing the burden on municipal water supply and wastewater systems by 10% and 20%, respectively, from the baseline established in the prerequisite. This can be accomplished by reducing fixture water usage through automatic controls and by installing water-efficient plumbing that exceeds EPAct fixture requirements in combination with ultra-high efficiency or dry fixture and control technologies.
Table 2
Retrofit Options for Existing Buildings
Facility renovations and building additions, of course, offer prime opportunities to retrofit or install new water-efficient plumbing products and systems in the restrooms. With or without a major LEED project pushing the need for plumbing updates, there are many factors driving the water-efficiency trend in existing installations. These factors include rising water and sewer costs, and local water-use restrictions.Water closets are the biggest water users inside most commercial buildings, so it makes sense to focus on water closets and urinals in relation to the water savings within your water-efficiency plans.
Restroom renovations sometimes call for completely replacing the existing plumbing products with new, more water-efficient models. Flushometers using 1.6 gpf or less would not work on 3.5-gpf toilet bowls, for example. In this case, to maximize water savings and maintain performance, replacing the fixture is required. Plumbing engineers should always ensure the fixture flush volume matches the flush volume of the flushometer valve.
When considering technologies such as pressure-assist 1.0-gpf toilets or waterfree urinals, it is mandatory to replace the existing equipment with new fixtures. These systems cannot be retrofitted onto existing fixtures.
Many property managers try to find some way to retrofit their facilities without removing the old water closets or urinal fixtures. What they may not realize is that this is a fundamental part of the process. It may cause a minor disruption, but it’s worth it to achieve the savings and maintain peak performance.
When the owner simply cannot justify replacing the fixture, low-consumption flush valve retrofits are an alternative. In some cases, it is possible to replace the old 3.5-gpf parts with 2.4-gpf parts. This saves 1 gallon per flush; however, some level of performance may be lost. Of course, the best performance option is a complete fixture retrofit.
High-Efficiency Urinals (HEU) and High-Efficiency Toilets (HET) are becoming increasingly popular. Some jurisdictions have passed laws requiring them; HEUs and HETs will be mandatory in California by 2014.
Ultra water-efficient HEUs by definition use no more than 0.5 gallons of water, and they can flush very effectively with as little as 1 pint of water or less. Non-water supplied urinals also are considered HEUs. If your building has older valves that flush with a few gallons of water, investing in HEUs would be a wise move.
HETs lower water consumption by about 20% to 40%, and because water closets account for the highest amount of water used in the restroom, these savings are huge. HET water closets are defined as using 1.28 gpf or less and are engineered to work effectively with no degradation in performance. In fact, they are required to meet the same performance requirements as 1.6-gpf fixtures, including flushing performance and drainline carry.
Dual-flush technologies, which fall under the HET category, provide a couple basic advantages: They substantially reduce water usage and offer a good return on investment. Dual-flush flush valves can be manually or electronically activated. Manual dual-flush valves have been commercially available in the United States and Canada for a few years. Electronic dual-flush valves are newer to the commercial market. In a few cases, facilities that have already installed dual-flush flushometers are reporting water savings of as much as 50% with great response from their regular restroom users.
With manual dual-flush systems, restroom users can choose a reduced or regular flush, depending on need. Push the handle one direction and get the full 1.6 gpf. Push the handle the other way for the reduced 1.1 gpf flush.
The new electronic dual-flush valves feature buttons for selecting a flush cycle. If a user walks away without pressing a button, the valve automatically initiates a full or reduced flush cycle based on how long the user stays in the sensor range. Although it’s just a matter of time before dual-flush valves are commonplace, this automatic operation immediately overcomes restroom visitors’ learning curve because it doesn’t rely on user selection or habit change.
Dual-flush functionality can be retrofitted onto installed flushometers or as part of complete systems. When adding manual dual-flush functionality to an existing flush valve, you simply replace the standard flushometer handle with a dual-flush handle. The dual-flush retrofit handle will work on most standard 1.6-gpf flush valves. It is a good idea to check with the fixture manufacturer before doing large-scale renovations.
By specifying plumbing systems that automatically save water, either by having a lower water consumption or due to sensor operation in the case of the electronic dual-flush flushometers, you’re helping the facility save water - even if restroom users are oblivious to the technology.
Putting It Into Practice
In addition to LEED, movements such as the Clinton Climate Initiative, which is working to accelerate the development and usage of energy-saving technologies, show the momentum of sustainable issues. As corporations come under greater pressure to treat sustainability more seriously, plumbing professionals also are finding that they need to give more than just lip service to these issues.Plumbing engineers have a responsibility to recognize the effectiveness of water-efficient plumbing systems and to recommend appropriate products to help achieve facilities’ overall sustainability objectives. For some building management companies, LEED: EB can make a difference in attracting and retaining tenants, as well as for elevating their reputations.
In 2007, Chicago’s Merchandise Mart, a 4.2-million-square-foot facility with commercial offices, wholesale showrooms and trade show space, became the largest commercial property thus far to earn LEED-EB Silver certification. LEED is important to the facility, which is home to the famed Merchandise Mart Design Center and is a showcase for some of the top commercial design and furnishing companies in the world. The Mart’s management firm estimates that the facility now saves 5.5 million gallons of water annually, partially due to the installation of water-efficient plumbing systems - and this is just one of its many environmental initiatives.
“We don’t view this as a completed project,” notes Myron Maurer, senior vice president of the Merchandise Mart. “We have developed the tools that we now use in our day-to-day operations. The Mart is going to continue to refine and improve our green building practices.”
Future goals include further reductions in water usage by installing more efficient fixtures, optimizing energy efficiency through lighting retrofits and encouraging the use of renewable and alternative energy sources.
LEED-EB: O&M provides a great framework for sustainable retrofits of existing buildings. These retrofits will provide consistent work for the trades, as well as the engineering community. Making clients aware of the opportunity and demonstrating the knowledge of the process will provide a substantial flow of projects and have meaningful environmental impact.
Michael Carson, senior mechanical engineer at Purdue University
Purdue's Dual-Flush Numbers Show Dramatic Water Drop
Talk all you want about how well a product works, but there’s nothing like cold, hard data to prove a point and make someone a believer. When Michael Carson, senior mechanical engineer at Purdue University, first heard about UPPERCUT dual-flush flushometers (from Sloan Valve Co.), he was skeptical.“We were curious as to whether it would make a difference,” Carson remembers thinking when he and his co-horts were offered a chance to test dual-flush flushometers at Purdue’s main campus in West Lafayette, IN.
Purdue initially decided to retrofit the women’s restrooms in two of its administrative buildings with a total of 12 new dual-flush handles. Carson and his engineering team chose the printing services and telecommunications buildings because both have good historical water-use information, restroom plumbing fixtures are the buildings’ only major water source and women comprise a high proportion of the populations.
Purdue installed the dual-flush handles in the women’s restrooms in these two buildings in July 2005. Carson and his team have closely examined the monthly water-use data from the buildings’ water meters, and the figures tell an interesting before-and-after story.
Regular
users of the Purdue University restrooms, in which the dual-flush flushometer
handles have been installed, are happy to do their part to reduce water usage.
That equates to about a 43% decrease in water usage.
In the telecommunications building, water use dropped from about 12,229 gallons a month (July 2004-June 2005) to 8,622 gallons (July 2006-June 2007) for a total median decrease of nearly 30%. Some single month-to-month comparisons yield a drop of almost 50%.
Carson solely attributes these decreases to the new dual-flush handles, because no other water usage or fixtures changed in the period studied. “The numbers are straight water meter readings,” he says. “We saw no other cause for the water use to drop.”
