Calculations from Rose

Good News!

I was really (REALLY) concerned about the amount of water we were going to use - really the only way to use water in a complete sustainable way without impacting the surround ecosystem is rainwater harvesting. Assuming that all of the buildings are single story and we can harvest water from all of the roofs (total of 24,690 sq ft) and assuming it rains about 4.5 ft (or more) per year, we can collect over 831,000 gal/yr! Thats good; we can assume that all of this is clean, potable water.

Unfortunately, I did some more calculations and found that for 500 people using the campus (300 residents, 200 commuting) we would need about 1,327,000 gal/year (this is for showers, washing hands, brushing teeth, washing dishes, and drinking) - which leaves us about 500,000 gallons/year short (if we assumed it rains 5.5 ft/yr (which it might in the mountains) we'd only be short 300,000 gal/year). (Calculated these numbers using WaterFootprintCalculator and the attached spreadsheet.)

Luckily we're not starting off with that many students, and if we just have 250 students to begin with and very few actually living on campus, we'll actually have an excess of 500,000 gallons/year.

So fortunately, we can collect most of the clean water that we need from the rain. The water that is used and recycled is called "grey" water and we can use these to run the toilets on - or if people are using biodegradable soaps, etc, we can divert the water to flowerbeds, agriculture, etc. If we use composting toilets, we wont need to worry about this either.

Just thought I'd share - we DEFINITELY need to think of water harvesting with all designs we come up with. It is THE most ecological way to get fresh water.

Hope you're well - see you Thursday

Rose