Have you ever lay awake (I had to google lay vs laid vs lain – I think that’s right) at night wondering how much energy and money you could save by switching to more efficient lighting?  If so, prepare to be enlightened.  Kevin and I both recently earned the Certified Energy Manager credential and wanted to flex our energy-audit-calculation-explaining-muscles a bit, while hopefully imparting a bit of knowledge for energy audits, the CEM exam, or otherwise.  This is the first in a handful of posts, in no particular order, on how to calculate energy savings.  We’ll start with an easy one first.   Try this at home (or pay us and we'll do it for you).

Let’s say you have recessed lighting in your kitchen – 5 fixtures with one 55 watt flood light each.  You want to know what you’ll save by replacing them with LED lamps (BR30s) at 13 watts each.  Estimate how long they’re on per day, on average.  Let’s assume 4 is hours is reasonable and you’re not leaving them on unnecessarily.

Energy Savings

Annual Cost Savings
Look at your utility bill to see how much you pay for electricity consumption.  Let’s assume 10 cents per kWh. 

Simple Payback
BR30 LEDs start around $30 dollars.  MassSave has rebates/incentives for qualifying products for residential projects as well as commercial projects (which are under the Bright  Opportunities program - no relation to Kevin).  Let's assume an incentive of $5 per lamp. There is no labor cost if you do it yourself, but this is where you’d add labor.

So it pays for itself in 4.5 years.  As you can see from the equations, if you focus your efforts on your highest wattage lamps that are on the most, the savings will be greater and it’ll pay for itself even faster.

I've been congratulating myself on that subject header all day, though unless you were in middle school in the 90s and hooked on pop radio, it's probably worse than than mundane. I'll tread lightly with the puns for now, lest I precipitate (ok, ok, sorry) a steep reversal of the 75-fold increase in the number of unique visitors our website received after the first post yesterday (the nice thing about a historical average of 0 visitors per day is that any stat is impressive).

Maybe I've been looking up more often lately, but it suddenly seems like several new renewable energy installations - specifically photovoltaic systems -  have been brought to light in my neighborhood in the past year.  I was curious where they're all located.  I'm a sucker for a good Google map, and I particularly like that the one the Massachusetts Clean Energy Center created is maintained via a green jobs program.  Check it out here. 

If you live or work in Cambridge and are curious about the general potential generation, energy savings, and financial savings for PV on your roof, the MIT Building Technology Sustainable Design Lab has created an impressive tool to help you answer those questions.  Read more about it here.

Pretty, huh?  So the basic goal is:  Figure out how much potable water is being used to make the landscape look this nice, and how consumption can be reduced. I recently undertook a basic audit of a large, multi-zone irrigation system, and while the study is nothing ground-breaking, I figured I'd share the process for anyone who has ever shaken their fists to the heavens after seeing sprinklers on during a rainstorm, watering half the sidewalk, the sides of buildings, unsuspecting passerby, and practically everything but a scraggly postage stamp-sized piece of turf.  Hopefully the post won't be too dry or watered-down.  (Sorry, couldn't resist).  Findings and recommendations will be shared as they're developed. 

1. Inventory the types/location/numbers of plantings, delivery methods, the zoning for the systems, and the controls.  For plants: location, how many, type, high/low water users?  Delivery methods: spray heads or rotary heads (including efficiency, gpm, psi), drip irrigation?  For controls:  tied to a rain sensor or manual?  Take note of old school controls (which don't account for the moisture of the soil) vs shiny new controls.  The one on the left is pretty much self-explanatory - it's completely manual.  The smart controller on the right does lots of cool stuff - look at this for more details:  http://www.rainbird.com/documents/turf/ts_ESP-MC.pdf

2. Talk to the maintenance staff about watering practices for each zone - months, days of the week, time of day, and duration.

3. Record meter numbers for each zone to look for historical usage for the meters.  In this case, it appears that the city isn't billing based on actual usage, which will make the job a bit more difficult.  Find someone tall and flexible for those hard to reach meters:

4.  Analyze the meter data and compare it to a benchmark.  Look at consumption patterns for abnormalities.

One intent of the audit is to align the system with LEED EBOM best practices and requirements under WEc3 - Water Efficient Landscaping.  In this particular system, the watering practices are reasonable, so the recommendations will focus on the delivery methods, controllers and the potential for rainwater reuse.

So that's the high-level idea...findings and recommendations will follow as they're developed.