Our project is a 700,000 square foot health centre. Because of the varying occupant numbers in a hospital (including patients, staff and visitors) we propose an alternative method of calculating this credit. Rather than basing the calculations on the number of occupants, we have calculated our water use based on the total number of each type of applicable fixtures in the building and the estimated number of uses for each of these. For example, for the public W.C. our calculation is as follows: Total Daily Water Use (Public WC) = Total Number Of Fixtures x Estimated Daily Uses x Flow Rate(GPF) x Duration As required, our calculations use the same fixture count and daily use numbers for the base and proposed case. This should provide a reasonable representation of base and proposed case water use. As per previous rulings, our calculations include all flush fixtures and the following flow fixtures: - public and private lavatories - public and private showers - kitchen faucets - clinical, scrub up and service lavatories Also per previous rulings, we are excluding the following as process loads: - eyewash fountains, emergency showers, water coolers, and water fountains dishwashers etc. Please confirm that our approach is acceptable.
Since a hospital project has a variable and transient occupancy, the project team has proposed an alternative method for calculating water use reduction based on estimated daily fixture uses rather than estimated occupant usage. The proposed method sets a usage baseline for each fixture type. The base case and design case calculations use this common usage factor to determine water use savings. While it is preferable for projects to use the prescribed occupant usage factors for calculations under this credit, it may be difficult to obtain a reasonable representation of water usage in projects with high transient occupancies. The proposed method is an acceptable alternative for use by projects of this type to calculate water use savings under this credit.