W10: Condensate Water Recovery System – Above Green

Requirement Summary

This measure can be claimed if a condensate water recovery device with the capacity to collect all condensate water from the cooling system is installed and the condensate water is used in landscaping, toilet flushing or for outdoor uses.

Intention

By recovering the condensate water from HVAC equipment, the use of fresh water from the municipal supply can be reduced.

Approach/Methodologies

Buildings benefit from condensate water recovery, which does not require much treatment and saves water for other purposes within the building and landscaping.

To qualify, the design team must demonstrate that the HVAC system has a collection device for the condensate water recovered. The collected condensate must have a piping system and collection tank or can be directed to the rain water collection tank if present. The collected water must be used in the building, such as for toilet flushing or on-site irrigation.

Potential Technologies/Strategies

In the context of buildings, condensate water recovery aims to re-use the water arising from the dehumidification of the air in HVAC or refrigeration systems. When the air passes through the cold coil of the system, the temperature of the air is decreased and the vapor (humidity) changes from gas to liquid, which can then be removed as condensate. It is essentially distilled water with low mineral content, but it can potentially contain harmful bacteria such as Legionella. This water can potentially be used anywhere in the building except for drinking, if proper treatment to address biological contaminants is considered. Potential use of condensate water includes:

Irrigation: generally safe to use without treatment, if used as surface irrigation;
Cooling towers: treatment is needed;
Water for decorative ponds or fountains: treatment is needed;
Toilet and urinal flushing: treatment is needed;
Rainwater recycle system: condensate can be a source to feed the system; and
Laundry and washing: biocide treatment required.

Condensate can be a constant source of water if the HVAC system is in use. It can generate between 11 to 40 liters/day per 100m² of conditioned space56, depending on the HVAC system type and operation. Collected water must be in accordance with local or international health and sanitary code requirements (whichever are more stringent).

Relationship to Other Measures

Claiming this measure reduces the water demand for the kitchen (dishwasher, rinse valve and faucets), bathroom faucets, the HVAC system and “Other” Water use, which is mainly cleaning.

Assumptions

The base case assumes there is no condensate water recovery from HVAC, while the improved case assumes that all condensate water generated from the HVAC system is recovered.

Compliance Guidance

To demonstrate compliance, the design team must provide documentation to support the claims.

Design Stage

Post-Construction Stage

At the design stage, the following must be used to demonstrate compliance:

Calculations for condensate water recovery specifying cooling load and water collected in liters per day; and
Hydraulic layout drawings showing the location of the recovery, collection and reuse technology.

At the post-construction stage, the following must be used to demonstrate compliance:

As-built hydraulic drawings with the location of the recovery, collection and reuse technology; and
Photographs of installed equipment related to the system.