Municipal Water Demand
The rainwater harvesting system and low-flow fixtures are designed to reduce the building’s annual demand for municipally treated potable water by 110,660 gallons. This is easily enough water to meet the annual demand of an average four-person household. Annual water/sewer savings are predicted to be around $1,000.
Any new development within the City is charged "Systems Development Charges" (SDC) to pay for infrastructure to deliver and remove water from the building. Concerning water usage, the standard dwelling unit is presumed to demand/contribute 650 ft3 of water per month from/to the municipal system. This is roughly equal to that of a three-person home and the building owner is charged accordingly. All apartments are assessed and charged 80% of this number and PSU pointed out to the City that studio apartments consume much less than 80% of the standard dwelling unit. The City and PSU thus came to an agreement by which PSU will monitor actual water usage for one year and the City will charge them an SDC based on the monitoring results. PSU projects that it will use about 40-50% of the water of a standard dwelling unit, largely due to the rainwater harvesting system that will reduce the amount of incoming water, thus saving roughly $80,000.
Energy Cost Savings
The integrated energy efficient building design provides 35% energy savings compared to a Code-compliant baseline building. This reduced the building’s energy cost index from $1.39 per square foot per year to $0.93 per square foot per year and translates to $29,000 in annual energy cost savings.
The energy efficient building emits approximately 360 tons of carbon dioxide equivalents less than a code-compliant baseline building annually. This is equal to the combustion of approximately 150,000 gallons of gasoline and roughly 8,500 tanks of gas.
City building codes require that individual dwelling units are submetered for energy use but PSU appealed this requirement citing the heat recovery feature and energy efficient design as sufficiently promoting conservation. The City approved the appeal and PSU saved $80,000 in capital costs.
Emerging Technology Grant
The City of Portland Office of Sustainable Development’s G/Rated Program rewarded the innovative rainwater harvesting system a $15,000 Emerging Technology Grant to offset the $33,000 capital cost and demonstrate the potential for transferability to other projects.
PSU anticipates that Epler Hall will earn a LEED Silver certification.