Sunday, September 21, 2008

Measuring Things - Energy and Water

Well gang - we're sorry it's been so long since we've posted anything to this site, but we've been a bit busy getting the kids off to their school and being on the local radio station.
Kevin has had his 15 minutes of fame come and go due to his appearance on the local radio program "Everything Green" on AM 950. Follow this link for the podcast if you care to hear the melodious musings of Kevin talking about our house.

This time off from attending to our blog doesn't mean that we haven't been doing things. Far from it oh unforgiving masses, far from it. We've been growing quite some grass, getting our home energy rating tests completed, and tracking energy use and water use in the house.

First things first. As part of our quest to know how we're doing and to see the impacts of some of our decisions during design, we've decided that we'll measure how much energy and water we use as well as how much water we can harvest and divert.

Our house has scored very well on the Energy Star Rating System after a series of blower door and air leakage tests we put it through to verify that the house was working as designed. The house scored well - receiving a 5 + star energy rating (the highest you can get) with a HERS Index Rating of 53 (on a scale of 0 to 500, with lower scores being better). This is great news - especially for a remodeled structure of which we were unable to change a few fundamental things. If we were to do a completely new house - I'd expect a HERS score of 30 or lower.

Our solar panels have been working hard given the summer days and relatively sunny skies of the season. Unfortunately, due to a small programming error in the data logger, we've lost the production data for June and half of July. We can, however, report energy production for mid July through mid September - during which time we produced 453 kwH - averaging 7.1 kwh per day during this period. This represents about 50% of our total electrical energy load for the same period. We've actually been a little surprised that our electric usage has been as high as it has been - given that we've rarely had to turn our lights on - but suspect that Kevin's new office equipment (a few new workstations and server) has caused out plug load to increase beyond expectations. We're going to meter these circuits separately so we can separate office from residential energy use in the coming months.

We'll expect to see solar pv production drop in the winter months but hope for a minimum production of 1,900 + kwh from our solar panels annually.

We've also been measuring water savings - both in terms of water usage within our home and the stormwater management practices employed on the rooftop and at grade.

Within the home, you will no doubt remember kind reader, we have outfitted the place with low flow plumbing and laundry fixtures. For our family of five (plus constant guest and 2 office staff) we would expect a baseline water use of 54,000 gallons per year (4,500 gallons per month) if we used plumbing fixtures that simply met the building code minimum standards. By our calculations, we are using only 32,600 per year (2,700 per month) for a potable water savings of 40%. This water use still seems very high, so we need to double check the flow rates on our dishwasher and laundry washing machines to get a more accurate number. I expect that we're closer to 60% - but we'll find a suitable means to measure that and let you know!

On site - we have a goal of sending ZERO water to the storm sewer system. We hope to accomplish this by means of:

  • A vegetated green roof system on 55% of our rooftop area: (To be installed in early October, we expect this to absorb 45% of the total rainwater on the rooftop)

  • Harvesting of rainwater in rainbarrels: So far we've collected and diverted 7,300 gallons of rainwater, or 16% of the total rainwater hitting our rooftops for July, August and September. We expect this number to increase significantly after we install the green roof.

  • Use of raingardens to handle remaining rooftop drainage, sump pump drainage and over surface drainage: Excess rainwater run off from the roof that is not collected by the green roof and rainbarrels as well as the water from our sump pump (below grade water at foundation wall) will find its way to the big raingarden - keeping those native plants happy.

  • Minimize impermeable surfaces on site: Excluding the footprint of our house, we have nearly 85% of our site in vegetated or permeable surfaces. - This makes for better infiltration into the groundwater and subsurface aquifers. More than 50% of our lawn is planted with a low mow native plant species grass mix that requires less water and little to no mowing! Except of course that Roxanne enjoys mowing the lawn and is itching to do it.

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