We just approved the 20th Thousand Home Challenge project! Congratulations to Ruth von Goeler and Kelly Slough of Northampton, MA. They participated in National Grid’s Deep Energy Retrofit pilot in 2012. Their OPTION B threshold was 13,071 kWh (OPTION B inputs - fossil fuel heat, 4 in household, 3,208 FFA, and 6,208 HDD (base 65). Andrew Webster of Coldham & Hartman Architects was the project manager.
Their annual energy for the post retrofit monitoring period was 8,136 kWh. Their 110-year-old home was previously insulated and had a relatively efficient heating system. As part of the retrofit they substantially increased the finished floor area and still achieved a 61% reduction in energy use from their baseline.
Attached is a spreadsheet with data from our twenty completed projects.
Interesting numbers, ranges, means, and comparisons! I welcome your observations. What is most interesting from the attached spreadsheet? Please provide suggestions for charts and graphs to tell the story of the 1000 Home Challenge projects to date.
6.9 kBtu/ Ft2: Avg Energy Use Index (EUI); US National avg. 44.8 kBtu/ Ft2 (single family homes)
1.91 kWh/ Ft2: Avg. THC Whole House Energy Use; US National Avg.: 14.27 Ft2
(5) Net Zero or Better
(3) Also charge Electric Vehicles
1,709 kWh/year: Average Energy Use per Occupant
4,554 kWh Average project energy use; 31,389 US National Avg: 31,389 kWh/yr
8,108 kWh Average project Thousand Home Challenge threshold
USE OF PV
(17) Homes have PV; (8 of 20) Projects met the Thousand Home Challenge without PV
(93 kW) Total installed PV Capacity (17 homes)
HOUSE & HOUSEHOLD CHARACTERISTICS
1869 Oldest home; 2008 Newest home
Year Built: (20%) 1850-1899; (25%) 1900-1930; (15%) 1931-1960; (30%) 1961-2000; (10%) 2001-2010
Correlation between indicators of energy performance and age: None
576 Ft2 Smallest home; 3,208 Ft2 Biggest single family home
2,271 Ft2 Average house size (per household)
1.73 Occupants: Average household size
(18) Single-family homes; (2) Duplexes
The attached bar chart shows EUI (Energy Use Index) of our 20 completed projects.
As stated above the average for the first 20 projects is 6.9 KBtu/ft2; national average for single family homes is 44.8 KBtu/ft2.
This chart also provides an indication of project cost (H - High, M - Medium, and L - Low). You do not necessarily need to do a complete deep energy retrofit of a home to achieve a deep energy reduction in energy costs. However, as with the Sloan/von Gouler project, the value proposition of a deep energy retrofit goes way beyond lower energy costs.
Here is the link to Coldman & Hartman's post regarding the Sloan/von Goeler home on http://www.coldhamandhartman.com/news.php?id=99
Thanks Linda. What I found interesting about the spreadsheet data you've shared is that it shows that achieving DER is possible with any age of house with or without PV with varying amount of investment. This means a homeowner can be creative in their path towards DER as long as there is commitment and focus. Good news!
We are THC candidate and have few more months to billing data to collect to complete the first year of occupancy. The monthly average on our our energy bill has been 279 kWh/month for the past 8 months. We'll see how this passive house performs in the winter months.
You can do it, Chie! What's your yearly kWh THC threshold? Unless it's really low, it sounds like you're on track.
Thanks Chris! Our Option B threshold is 5331. We have solar thermal but no PV (yet) and we would be delighted to meet the THC threshold without PV.
What is your gas usage to date? Is the 279 kWh just your electric use, or does it reflect gas and electricity? As I recall, you use electricity for the clothes dryer and cooking, and gas for water and space heating, correct?
I have really enjoyed your blog. Please add the link to it for folks who may want more info about your project.
Thanks for all that you do. Great to see the THC Home Energy Pros page lively again!
I share your concerns about using EUI as a metric. Any metric that is based on square footage of living space favors bigger buildings and penalizes smaller buildings.
I envision that we need a constellation of metrics to tell the story of a home's or an initiative's energy performance. It was only recently that I worked the THC OPTION B allowance backwards to see what the range of EUI would be for different climates, house sizes, and occupancy.
OPTION B of the 1000 Home Challenge generates a threshold that balances a number of inputs, and only uses finished floor area in order to estimate shell surface area (five sides). Below is a graphs that I find interesting. Hopefully, as a result, the OPTION B allowance meets the objective of being difficult to achieve across the full range of North American housing stock - ideally not favoring warm climates, cold climates, big homes, small homes, old homes, new homes, energy hogs or energy misers, homes serviced by low carbon electricity, or homes serviced by hydro.
The Option B criteria themselves do an excellent (heroic, beautiful, gold-standard -- what other superlatives can I think of?) job at controlling for all the factors you cite, normalizing the difficulty for homes having different occupancies, behaviors, climate zones, heating types, etc. But then in the end to subvert all that innovative, clear thinking by comparing performance using EUI -- seems strange. I understand the rationale -- it's a commonly-cited and broadly-understood metric. But then again, hey, whatever it takes; if EUI motivates and engages people and is not used in the certification process itself (but only after the fact), I'm all for it.
I used this as the subject line "Measured Performance - Avg EUI 6.9 KBtu/ft 2 - Twenty THC Projects - US Avg 44" of an e-mail to some folks who I thought would be interested in the Home Energy Pros post.
It worked. It got your (and others) attention.
Regardless of how misguided of a metric it may be, 20 projects with an average EUI of 6.9 kBtu/ft 2 is impressive. If a person is not familiar with the term, it is still obvious that is is substantially less than 44 kBtu/ft 2 (national SF residential average).
I think it is important to translate the performance in a wide variety of ways.
RE: Your suggestion re Conveying Carbon Emission Reductions
We have carbon emissions embedded in the Thousand Home Challenge application (based on national averages), so that could be tracked. Even if it is full of assumptions, it would help to convey that projects that meet the THC thresholds achieve a substantial reduction of carbon emissions regardless of the energy sources they choose.