NET-ZERO WATER USE IN HIGH-RISE BUILDINGS: A Study in How to Achieve It and Make Money Doing So

The climate today is tough, particularly in the western U.S. where the drought is ravaging the environment and mandating water restrictions. California has particularly been hit hard, with more than 97% of the state affected, and 46% of the state still at exceptionaldrought levels according to the NOAA.

How do we combat this? In a phrase: Net-zero water use. Buildings in the United States use roughly 47 billion gallons of water per day this represents 12% of all water use each day. Fortunately, there are high performance building strategies that can be leveraged to achieve net-zero water use in high-rise buildings, allowing for the reuse of wastewater in an environmentally-friendly and financially-beneficial manner. Net-zero water use ensures that a building never uses more water than it produces.

Lets take a look at how net-zero water use can be achieved through water use reduction and water generation strategies, and how it all can affect your bottom line.

Water Reduction

With the average office building utilizing 12 gallons of water per square foot each year, there is much to be done that can contribute to smart water reduction. Reduction can be achieved through smart plumbing fixture selection, efficient heating and cooling equipment specification, and low-water use irrigation strategies. Lets glance at each.

Restrooms Water savings can be achieved in restrooms through simple off-the-shelf plumbing fixture installations. Altering the flow rate of restroom appliances can greatly save water; in fact, you can achieve approximately 40% water savings over what the plumbing code mandates by leveraging fixture flow rates on urinals, toilets, sinks, and faucets, often with the aid of a water-restricting aerator.

Heating and cooling Cooling tower water loss is the leading culprit behind high water usage in high-rise office buildings. Fortunately, cooling tower water cycles can be increased in order to effectively decrease water usage by approximately 20%. Also, an additional 20% reduction can be achieved by using more efficient cooling equipment in tandem with air-side economizers to reduce the overall need for cooling tower cooling.

Irrigation Incredibly, water savings through smarter, greener irrigation efforts can approach 80% without the need for many costly new pieces of equipment. The utilization of drought-tolerant plants, which is becoming increasingly popular in western states for office parks and homeowners alike, can contribute to most irrigation savings. Additional water savings can be realized through moisture-sensing irrigation controllers and drip irrigation.

Water Generation Strategies

Enormous strides toward net-zero water use in high-rise buildings can also be made through smart water generation strategies. Green building consulting teaches us that such generation can be intelligently performed through the combination of rainwater collection and a blackwater system.

Rainwater collection and reuse system Large buildings have an impressive ability to collect rainwater. A rainwater collection and reuse system efficiently captures, stores, and treats (if necessary) rainwater that falls around the grounds of high-rise buildings. This rainwater is then reused. While such a rainwater collection system can be utilized independently, it can also be combined with a blackwater reuse system for maximum effect.

Blackwater reuse system Two terms to understand when contemplating a blackwater reuse system: Blackwater and greywater. Blackwater represents all the waste water in a building generated from urinals, toilets and kitchen sinksGreywater represents all the other waste water generated by the rest of a building’s equipment.

A blackwater reuse system captures all on-site blackwater and greywater, treats it, and then reuses the water as cooling tower makeup water and toilet/urinal water. Also, a blackwater reuse system can be combined with sewer mining to achieve true net-zero water use. Sewer mining is a high-performance building strategy that allows for the collection of city sewer water from the local mains, and the resulting treatment of that sewer water within the buildings blackwater system. This strategy provides additional water for re-use at the high-rise office building in question.


So, heres the big question: After all this green building consulting and the application of all these high performance building strategies, how does it affect your bottom line?

Pretty well, actually. Estimates for the total price of all the aforementioned strategies sit at about $2.4 million. However, annual water savings as a result of these strategies are estimated to be 12 million gallons a year. When the average United States water cost is applied, this results in $140,000 in savings each year, making the entire enterprise cash-flow positive in just 11 years (factoring in annual water cost escalation of 9%). After that point, the value simply adds up each year.

Currently, an office tower in San Francisco is under construction using these net-zero water use strategies, proving the viability of the concept. And in todays water-challenged times, the demand for more such buildings is at an all-time high. Will your enterprise be the next success story?

NET-ZERO WATER USE IN HIGH-RISE BUILDINGS: The Importance in Today’s Climate

Its never been more important for us all to be good stewards of the environment and consider what we can do to reduce our water usage. Green building consulting tells us that one particularly incredible water reduction goal that can be achieved is net-zero water use in high-rise buildings.

Net-zero water use guarantees that the building utilizing this high performance building strategy never makes use of more water than it produces. But why is net-zero water use so important right now? The answer lies in the severity of todays drought, as well as the impact of such high performance building strategies on both building systems and the financial bottom line.

Lets take a look at each, shall we?

Severity of Drought

The National Oceanic and Atmospheric Administration (NOAA) brings to light the startling truth behind todays drought: 97% of California is drought-affected, and most western U.S. states arent faring any better. In fact, in Californias case, 46% of the state is at an exceptionaldrought level, putting the state at critical risk.

Here are some other worrisome drought statistics that illustrate the depth of its severity:

— Researchers say California is the driest its been in 500 years.

— Earlier this year California state governor Jerry Brown imposed state water reductions of 25 percent. This mandate represents the only time in Californias history that mandatory water restrictions have been put into place.

With groundwater levels at a new low, reservoirs in places like California only have approximately one year’s worth of water remaining.

— Folks in the western U.S. are using groundwater that fell 20,000 years ago.

Due to digging deeper to access this ancient groundwater, the state of California is literally sinking, and at a rate of two inches a month (and climbing)!

Impact of Net-Zero Water Use on High-Rise Building Systems

Despite the immense severity of the drought, theres hope thanks in part to water reduction strategies that lead to a building reaching net-zero water use. Reaching net zero water use, which combines water reduction strategies with the reuse of blackwater and greywater, can completely transform a buildings systems even at a high-rise structure.

Building’s account for 47 billion gallons of water use every day in America, which in turn represents 12% of total water use. However, water reduction thanks to low-water use plants, drip irrigation, special moisture-sensing controllers, and plumbing fixture flow rates can slash water use. A high-rise buildings restrooms, irrigation, and heating and cooling systems can all be positively impacted. Irrigation water savings alone can top 80%.

Further, the application of an on-site rainwater collection system and a blackwater reuse system can lead to the realization of net-zero water use, even in high-rise buildings. And since high-rise buildings represent perhaps the most difficult type of buildings when it comes to producing the same amount of water as a structure uses, these strategies can create an inspiring model that will boost wider market adoption.

Impact of Net-Zero Water Use on Your Bottom Line

If you implement net-zero water use in a high-rise buildings plans, youre going to find that your finances will greatly benefit, too. By implementing the above discussed high performance building strategies in an average 1 million sf building will result in estimated 12 million gallons a year saved. When considering national water price averages, this will lead to roughly $140,000 in water savings annually.

Thus, on top of doing your duty to the Earth, you can be cash-flow positive after installing the necessary net-zero water use systems in your high-rise building after just 11 years. Talk about peace of mind!