Sustainable Facilities Tool

Harvesting Systems

Harvesting systems – Harvesting systems capture and reuse non-potable on-site water sources for building applications not requiring clean water such as landscape irrigation and flush fixtures. As a result, successfully implementing an on-site harvesting system can drastically reduce potable water consumption. Examples of harvesting techniques include:

• Rainwater – Water stemming from rainstorms but not subjected to ground contaminants. The source is typically collected from the roof and can be subjected to minor purification by percolating through the layers of a green roof.
• Greywater – Wastewater from showers, faucets, and dishwashers that typically does not include solid particulates. Blackwater, or sewage from toilet and urinal processes, is not an acceptable potable water alternative without significant on-site treatment. Greywater is regulated on state-by-state basis. Work with local water jurisdiction officials to get approval for greywater projects.
• Condensate – Water droplets accumulated through condensation on cooling coils in air handling units (HVAC equipment).
• Stormwater – Water collected from drains or onsite streams.
• Sump – Water collected at the foundation of the building and pumped away to avoid flooding.

Bundles: Potable Water Conservation

System Relationships

Landscaping/Irrigation

The landscape surrounding the building envelope plays a critical role in the efficiency of the whole building water system by being responsible for nearly 20% of the total water consumption. Designing a landscape that requires minimal supplemental water (through considerate planning and selection of climate-appropriate plants) reduces the demand for on-site irrigation. Xeriscaping can eliminate irrigation needs altogether and should be the goal of any water project. For the areas needing supplemental water, use a water-efficient irrigation system with controls that detect the amount of water needed (and that avoid watering during rain showers). Exterior water features such as fountains should utilize non-potable water sources.

Find products used to contain, maintain or enhance landscaping products in the Green Products Compilation.

Bundles: Potable Water Conservation

System Relationships

Piping

Water is distributed throughout the building by a network of pipes. This network should be optimized through proper sizing, minimizing the number of joints and turns, avoiding water or steam leaks near fixtures and fittings, and where appropriate, providing proper insulation to avoid undesirable heat transfer. Pipes can move water for domestic, HVAC, and fire protection needs. Well-designed piping systems help reduce pump size and energy use.

Bundles: Optimize Energy Efficiency

System Relationships

Boilers/Steam System

Boiler and steam generators are commonly used in large heating systems or facilities where large amounts of process steam are used. Steam is often used for heating or in large kitchens. Steam condensate return and automatic blow-downblow-down systems reduce water supply, energy costs, and chemical use. Steam and hot water may be circulated throughout the building or grounds. These systems are subject to leaks that can contribute to water consumption. Utilizing chemical free treatments for boilers and condensors allows water to be used elsewhere without additional treatments.

Bundles: Optimize Energy Efficiency

Humidification and Evaporative Cooling

Your HVAC system may have equipment to add moisture to the air during dry conditions, leading to greater occupant comfort and reduced static building (which can affect computers and other electrical devices). Certain dry climates can make use of the cooling provided by evaporation, and HVAC systems can be designed to provide much of the building’s cooling needs with humidification alone. Avoid airborne water losses by ensuring that the building envelope is appropriately sealed so that humidified air is not lost to the outside. Desiccant wheels, a strategy for energy recovery, exchange moisture and heat between the exhaust and outdoor air streams. These systems can pay for themselves quickly in water and energy savings.

System Relationships

Drinking Water

Water coolers and water fountains deliver drinking water to building occupants. Each water fountain typically has its own compressor and refrigerant system to cool water. However, running these fountains all day with many small systems may be less efficient than a central water chiller and filtration system. Water that is delivered, in large water cooler bottles or single-serving bottles increases waste and transportation-related fuel use.

Bundles: Low Upfront Cost Bundle

System Relationships

Kitchen Processes

Kitchen processes such as dishwashing, ice making, steam-based heating trays, and running the garbage disposal all have environmental implications pertaining to the water system. Running the dishwasher only when at full capacity and specifying ENERGY STAR appliances not only reduces overall water consumption but also the associated energy needed to operate and heat the water. Consider replacing once-through water-cooled ice making machines with closed loop alternatives. Ensure tight fits between food trays and heating trays to reduce steam loss. Reduce the water used to convey food waste via conventional garbage disposals with strainers or mesh screens to collect food waste and use it for compost. Maintain all kitchen process equipment to achieve longevity in use.

Find kitchen process products, including cafeteria services and non-paper office products, in the Green Products Compilation.

System Relationships

Sewage Discharge

Once the water within the building reaches its end use, it is discharged to a sewage treatment facility to be eventually discharged to water bodies. Sewer fees are frequently more expensive than water consumption bills. Water-efficient equipment and water reuse strategies limit the quantity of water sent to the treatment plant. Onsite treatment may allow for additional on-site uses of waste water, such as irrigation or toilet flushing, which can be environmentally and fiscally preferable as sewage utility rates continue to rise.

Domestic Hot Water

Potable water is heated for use in showers and sinks. Water-efficient fixtures help reduce the amount of energy needed to heat this water. Leaks in the domestic hot water system are particularly expensive, as both water and energy are lost in the process. Typical domestic water heating strategies include:

• Central – A central boiler and pump system distributes hot water throughout the building. These systems are good for buildings with large and relatively constant hot water needs.
• Tank – This type of water heater is common in the home, with a gas or electric heat source and capacity for water storage. Energy is needed to keep this water hot, even if it is rarely used.
• Instantaneous/Tankless – These typically small heaters are placed close to the delivery point of hot water, such as under a sink. Tankless units do not store hot water; rather, they heat water as it passes through the unit on the way to its nearby destination. These units require a short but high power demand to heat the water quickly and are a good choice where hot water needs are infrequent.

System Relationships

Water (Plumbing) Fixtures

Water fixtures (plumbing fixtures) - Water fixtures such as toilets, urinals, faucets, and showers dispense water to building occupants for hygienic, cooking, or similar purposes. Implementing a fixture replacement and retrofit policy with technologically-advanced water-efficient fixtures significantly reduces overall water consumption. Alternatives to conventional fixtures include WaterSense labeled or label-eligible product types such as:

• Toilets – low-flow/pressure-assisted, automatic sensor, dual-flush, composting
• Urinals – low-flow, automatic sensor, waterless
• Faucets – low-flow, infrared sensored valve, metered valve
• Showers – low-flow, aerators, pulsators, atomizers

Reducing the amount of heated water for faucet and shower applications also leads to energy savings.

Bundles: Optimize Energy Efficiency Potable Water Conservation Low Upfront Cost Bundle

System Relationships

Pumps

Pumps are devices that use a motor to move a fluid from one place to another. In the context of buildings, pumps typically refer to the movement of water through pipes. Water often needs to be moved vertically or across long horizontal distances for use, such as the cold water originating from the chiller that needs to get to the air handling unit in order to cool rooms in the building. Pipe size, material, and routing through the building all affect the workload for a pump. Pumps should be sized to operate at peak efficiency under conditions it will experience most often. Pumping systems can be made more efficient by using variable speed drives to use less energy during partial loads. See more tips for pump efficiency in the Federal Energy Management Programs “Operations & Maintenance Best Practices” guide.

Boilers

Boilers use electricity, natural gas, or other energy sources to heat water or create steam for heating systems throughout the building. Boilers can be used for domestic water heating as well. Many opportunities exist to increase the efficiency of existing boilers. However, if you are in need of a new boiler, choose a high efficiency option. The average existing boiler loses 24% of the energy intended for heating right out the flue, before it does any useful water heating. Modern boilers can exceed efficiencies of 90%.¹ Maintenance is key to proper boiler operation. See tips on how to keep your boiler system running well in the Operations and Maintenance section.

1.US EPA - ENERGY STAR Building Upgrade Manual

Bundles: Green Roof and Hot Water Green Roof and Hot Water