The Environmentally Responsible Construction and Renovation Handbook

Chapter 7 - Implementing Water Conservation

Water consumption in a green office building should be significantly less than a similar building typical of current renovation practices. The goal of 30% reduction in water use in renovated and fit-up buildings relative to a conventional office building with similar features and systems is considered achievable in many cases. Life cycle cost analysis was used to ensure that the systems prescribed are cost effective. The methodology used to assess the economic viability of retrofitting water conservation measure for any particular technology is given in RPSB 5 Phase Water Audit Protocol Workbook. The same methodology can be used by the designer to assess technologies that have not undergone economic analysis elsewhere, or it can be used to verify the economic viability of previously assessed measures if it is believed that the given analysis is not representative of a particular situation.

Requirements for extension, alteration, renewal or repair of plumbing systems are set out in the National Building Code of Canada. The NBC requires that every plumbing system shall be designed and installed in accordance with appropriate municipal, territorial, or provincial regulations or, in the absence of such regulations, in conformance with the National Plumbing Code of Canada. Specific requirements for meeting the GOP are incremental to the National Plumbing Code, and are generally cost effective.

Water conserving measures are divided into three categories; domestic water, HVAC, and landscaping, and are discussed in the following sections.

7.1 Domestic Water

Domestic water consumption is a significant component of water usage in an office building. There are a growing number of products available to help reduce domestic water use in any building. Installation of water conserving equipment and implementation of water efficient procedures are capable of providing considerable cost-effective savings, particularly in areas where water is metered and costs are directly proportional to usage.

These have been written in language which is easily incorporated into project specifications, or is clear for discussion with material suppliers.

• All faucet aerators to have a flow rate of not more than 4 L/min @ 413 kPa
• Shower heads to have a flow rate of not more than 7.6 L/min @50 kPa. Shower heads shall have a manual or automatic shut-off feature. Clear, understandable signage shall be posted explaining its use and requesting diligence in it's use.
• Water closets to have a water consumption of not more than 6.0 L/flush
• Urinals to have a water consumption of not more than 3.8 L/flush
• Dishwashers - If dishwashers are to be installed or replaced chose water efficient dishwashers. Residential type models shall use no more that 24 L/cycle. Commercial load type washers shall use no more than 5.3 L/rack. Commercial conveyor type washers shall use no more than 21 L/m. This rating is based on a conveyor speed of 1.5 m² per min (feed rate times width). Water consumption for other speeds and sizes will be pro-rated to this value.
• Water Softener - If a water softener is to be installed or replaced chose a water conserving (counterflow) softener. Use electronic demand regeneration control to ensure regeneration is initiated only as required. Connect water softener to the hot water circuit in the building only.
• Bathroom Fixtures - All bathroom faucets, and all urinals shall have automatic shut-off feature. This can be either a spring loaded feature or infrared sensor technology.

Some of these measurements may be less economically viable sense in some parts of Canada. It will depend on water availability and cost, among other factors. To confirm economic viability of these options, get a quote for replacement of existing fixtures with those listed above and carry out a Life Cycle Assessment as shown in the RPS National 5 Phase Water Audit Protocol Workbook.

7.2 HVAC Measures

Heating, Ventilation, and Air Conditioning (HVAC) equipment can, by design, use a considerable amount of water. There are often opportunities for water conservation with HVAC equipment. The Project Manager should tour the building with the maintenance supervisor to ascertain the viability of each of the measures described below. Where viable, within the constraints of the existing building and the renovation project, the viability of the following measures should be assessed:

• No open loop equipment of any kind is to be installed. Any existing cooling equipment that releases water directly to drain should be replaced.
• Use a demand control to manage blow-down frequency in cooling towers. Water evaporating from cooling towers leaves behind the minerals and other particles commonly found in fresh water. As make-up water is introduced, the concentrations of these materials rise. Eventually, the cooling water must be purged in a blow-down cycle to avoid excessive accumulation of mineral and biological matter. These blow-down cycles are usually on timers that drain the entire system on a fixed frequency. Water quality sampling is to be done on a regular basis after system commissioning to ensure blow-down cycles are tuned to the local water and weather conditions.
• Use counter-flow evaporative cooling tower system with low drift loss specification - In larger commercial buildings, evaporative cooling towers use significant amounts of water. Water use reductions are achieved through good design. Counter-flow cooling towers are generally more water efficient than cross-flow types. Drift loss should be specified at no more than .002% of the total water flow.

7.3 Landscaping

Landscaping practices are an important target for water conservation measures. There are many alternative ways to reduce or eliminate water consumption in outdoor areas around a building without detracting from the practical and aesthetic aspects of the green space. Kentucky Bluegrass turf is a very water intensive ground cover and should be avoided as much as possible. Hearty native grass species such as rye fescues are readily available. Fescue sod is available from some sports field suppliers. Again, the viability and cost of these measures should be discussed with the Maintenance Supervisor for the building, and a schedule developed for incremental implementation of significant changes.

The following measures are required by the GOP for landscaping around buildings:

• Automatic irrigation systems will be set for maximum 15 mm/wk watering.
• Sprinklers will be adjusted to avoid overspray onto parking and other areas not requiring irrigation.
• Drought-resistant native plant species to be specified to cover a minimum of 70% of landscaped areas. Choose plants that are native to the area and that are well-adapted to the growing conditions at the site. A good variety of plants should be chosen with attention paid to growth rate, life span, and hardiness. Soil pH, light, and water requirements should be considered. Plants with similar needs should be placed together. Well-situated trees and shrubs can also help reduce cooling energy by providing summer shading on windows.
• Design to avoid over-watering. Automatic irrigation systems will be equipped with timers and electronic controllers to avoid watering during the day when evaporation losses are highest. A soil moisture sensor will be used to ensure watering cycles are initiated only on an as-needed basis. Most excessive water consumption in landscaping comes from over-watering of plants. Low volume distribution devices will be specified and operation verified to reduce water wastage.

Further information is readily available from many sources on water conserving landscaping. Techniques such as xericulture and enviroscaping can create attractive, low cost, low maintenance landscapes with a minimum environmental impact.

7.4 Documentation

A statement of the design intent and operational recommendations shall be provided and shall include:

• descriptive information about each system, detailing its function, design capability, performance characteristics and distribution arrangement;
• schematic and control diagrams and sequence of operation; start/stop adjustment procedures, and changeover, startup and shutdown sequences.

7.5 Additional Water Conservation Opportunities

There are a number of additional measures which should be considered for reducing water consumption. Renovating or refitting a building in line with the basic requirements of this Green Office Plan is a good start toward sustainable development in the commercial building sector. But, it is just the beginning. Additional features will reduce the impact the building has on water resources even further.

An on-going program of monitoring and continuous improvement needs to developed whereby additional conservation features can also be added as future renovation is carried on. It is important to ensure that the sustainable development principals initially implemented become a starting point for an ongoing process of continually developing sustainability. The measures listed below may not be feasible in every situation, but should be considered to go beyond the basic recommendations of the GOP.

The Project Manager should discuss the practicality and viability of these measures with the maintenance supervisor, and a timetable for implementation should be included in the GOP Documentation Report.

7.5.1 Domestic Water

• Locate water heater centrally to ensure short piping runs and insulate water pipes. Short, insulated piping runs ensure the user does not run excessive quantities of water waiting for the desired temperature of water.
• Use pedal switch on kitchen sinks. Pedal switches encourage the use of water only as it is needed. Leaving both hands free to perform the task required ensures water can be turned on and off as needed instead of allowing it to run unnecessarily.
• Consider evaluating a waterless urinal. Waterless urinals are now on the market and could bring water use for this fixture down to zero.

7.5.2 HVAC Measures

• Check and calibrate humidifier controls annually to ensure humidifier operation is maintained at the minimum possible.
• Consider the use of catalytic chemical treatments that maintain minerals in suspension to minimise the need for cooling tower blow-down (however, the environmental impacts of these chemicals must also be taken into consideration).
• Consider the use of rain water for cooling tower make-up.

7.5.3 Landscaping

• Reclaim rainwater. Landscaping water does not need to come from the municipal supply. Roof drainage systems can often be modified to direct rainwater to a cistern. Not only does this provide a good source of free irrigation water to be used when the weather is dry, it eases the load on the storm water system during heavy rainstorms.
• Select soils and mulches appropriately. Give consideration to soil type and its ability to hold moisture. Loose, rocky soil promotes drainage and will require more water. Mulches hold moisture well and can help provide a nourishing environment for plants.
• Install landscaping, porous paving surfaces and grass paving surfaces to ensure maximum rainwater retention and minimum run-off,
• Use an on-site storm water retention pond for collecting rain water and minimise loading on municipal storm water systems
• Install "grey water" system to provide water for irrigation and sanitary flushing.

7.5.4 Continuous Improvement

As part of an ongoing continuous improvement process a water use monitoring and conservation improvement team should be established. The team should be charged with ongoing monitoring and analysis of water use in the building or suite (as appropriate), investigation and cataloguing of new trends and technologies in water conservation and recommending improvements for additional reductions in water use in the building. The team should investigate wasteful practices that may be part of building operation or employee habits. Investigation of concerns and suggestions, providing feedback to employees on successes and providing constructive comment on potential areas for improvements are all essential components of the team's work.

7.6 Water Conservation Case Studies

7.6.1 Purdy's Wharf Office Complex, Halifax, Nova Scotia

Project Overview

The Purdy's Wharf facility is a new 350,000 square foot mixed-use complex located on the waterfront in Halifax. The project objective was to build a modern facility that would be capable of offering competitive rental rates by minimizing operating costs. As Purdy's Wharf was to be built adjacent to an unlimited supply of seawater, the developers decided to use this natural resource to reduce water costs.

Environmental Achievements

Economic Factors

The seawater cooling system was a $200,000 upgrade over a conventional cooling system, but it has proven to be very economical. In the first year, the system provided a $113,500 savings in operational costs by reducing water consumption by 8,400,000 litres. Furthermore energy costs were reduced by $50,000 to $60,000 annually and maintenance and chemical costs by $51,000.

7.6.2 Canadian Centre for Inland Waters, Burlington, Ontario

Project Overview

The Canadian Centre for Inland Waters (CCIW) was originally opened in 1967 and was fully completed in the early 1970's. The complex is located on Hamilton Harbour and contains over 49,000 square metres of space, including 200 laboratories ranging in size from one room to a 100 metre long wide-wave flume. The complex provides office and research space for 700 employees that research the effects of water pollution on aquatic ecosystems. Between 1985 and 1991, this site was renovated with assistance from the Federal Buildings Initiative. In addition to energy conservation refits, the building was upgraded to maximize water conservation.

Environmental Achievements

Economic Factors

The greatest cost incurred in this project was refitting the cooling system. This procedure involved a capital outlay of $101,000. In turn, this initiative resulted in annual savings of $53,000 annually. Paybacks were realized in two years. The rerouting of the water flow for the fish tanks required an outlay of $32,350, but resulted in annual savings of $22,600. The costs of the other water saving measures were included in regular maintenance costs and were therefore not calculated.

7.6.3 Green on the Grand - Commercial Office Building

Description: This 2,000 m² office is Canada's first C-2000 office. It is located on the Grand River in Kitchener, Ontario. The building was designed to showcase leading edge environmentally responsible building features and technologies. Paramount was the provision of a comfortable and healthy environment for occupants. Among the numerous and rigorous environmental goals was a water use reduction target of 70% less water use than comparable typical office building.

Features: All areas where water is used were carefully considered. Toilets had to use a maximum of 6 litres per flush but also required a high efficacy flush. Therefore pressurised-tank type toilets were installed. Ultra-low water use urinals with infra-red occupancy flush valves were used. As were water-saver lavatory faucets with infra-red sensors. Similar faucets were also used in tenant kitchenettes. The showers also have low water use shower heads and infrared occupancy sensors.

The cooling tower is a storm water retention / decorative pond located in front of the building and fed from the building's rain water leaders. Rain water provides much of the replacement water.

Over 75% of the landscaped area is covered in native species of trees, shrubs and flowers that require minimal watering. Bark mulch is used to ensure that moisture is retained in the soil and to keep weeds from flourishing. Grass is limited to the boulevards as required by the city and a small area that has a picnic table for a social gathering spot.

Results: An annual city water use reduction of 72% less than a typical office (or a use of 26 L/p/d) was predicted. Monitoring showed the expected consumption target had been met with an actual consumption of 73% less than a typical building.

Two issues have the potential to increase water consumption. First, after the building was completed the owner had a significantly oversized water softener with timed regeneration installed. Second, the city insisted on installing Kentucky Bluegrass on the boulevards and required automatic irrigation installed to ensure that it would not die and require replacement.

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