Hi Scott, greetings from North Seattle. You ought to visit my house. I'm cruising towards the finish line on a similar project. In addition to our shared goal of comfort, I have other goals: Net Zero (I'm at 95%), no fossil fuels, improved building safety (seismic retrofits, eliminate combustion appliances), minimal embodied energy, and IAQ. As others have mentioned, the means for getting a comfortable building is easy: insulate, insulate, insulate, air seal, and insulate. Not necessarily in that order, and sometimes you get two-fers like spray foam and properly flashed windows that do both. But the details is where it gets tricky. I got quotes to have my walls filled with dense pack cellulose and they were VERY reasonable. I'd have done it, except... I ordered 21 new windows and a 55' truck of reclaimed 3" poly-iso. That's enough to twice go around a 2400 sq/ft house and a 1000 sq/ft garage AND cover a 600 sq/ft roof with 3 layers. I'll see your R-21 minimum walls and raise it to R-36 thank you very much. (One minor downside: with R-36 exterior insulation, an IR camera is no longer useful as a stud finder.) I began a wall at a time: remove siding, fill all gaps and cracks with Dow Great Stuff Pro Wall & Floor, tape all seams (I tried several and greatly prefer Dow Weathermate), installed my z-flashing (I got bent by B&D sheet metal (dad pun intended)) and insect screen at the bottom edge of the rain screen, installed one layer of poly-iso (Allied stocks 4" screws and foam washers), foam fill & tape all seams, install a 2nd layer of poly-iso with offset joints foamed & taped, and screw through 1" furring with 9" screws (www.bestmaterials.com/detail.aspx?ID=16720) to the joists. (9" screws - 3/4" furring - 6" polyiso - 1/2 sheathing = 1 3/4 penetration into joist). If you're thinking, "3 in. of penetration will take a beastly drill and hardened bits," you'd be right. I had to upgrade my cordless drill and pre-drill the holes. On walls with windows and/or doors, I pre-constructed 6" bucks with 8" flanges from 3/4" marine grade plywood sourced off craigslist. Then I cut the insulation around the bucks and continued along. Once a wall was thus insulated and furred, I covered it with Tyvek and then flashed and installed the windows. It wasn't the most efficient way, but my family was living in the house so I considered it important to have the holes in each wall plugged before calling it a day. I started on the North wall (out of sight, good place to learn) and by the time I arrived at the South wall it was mid-summer. What a difference in comfort R-36 insulation adds. I chose triple pane low-e glass for my South and West facing windows. Once those walls were done the daily heat rise in our upstairs bedrooms dropped 20°. What a HUGE comfort bonus. I had an uninsulated floor over a crawl space so I bought a spray foam kit and sprayed an inch of closed cell foam to the underside of the subfloor and rim joists. Then I filled the cavities with fiberglass and to break the thermal bridges I screwed a layer of poly-iso to the underside of the joists. Cold floor no more. Unlike the walls, I did not tape the seams. If bulk water ever finds its way into the floor, I want it to leak through. I'm now trimming out the windows so I still have some bucks exposed and some of the flashing details visible. I've gleaned many of the techniques from GBA and the Building Science web sites so a big shout out to both sources (thanks Martin!).
Posted: 04:58 pm on November 15th 2017
I'd love to share pics but when I try to post a URL to my project page, I get blocked (for two weeks now). I sourced my reclaimed polyiso from insulationdepot dot com.
Posted: 03:08 pm on December 4th 2017
My project, with photos scattered throughout, is extensively documented at github.com/msimerson/330-NE-193rd-St. Issue #88 documents the first wall. I hadn't yet purchased the 4" screws and foam washers so I was still working too hard (trying to add 2 layers before any fasteners). I didn't tape the plywood seams on the garage walls. I foamed over the window opening and then cut them out with a hand saw. It wasn't easy to keep the blade straight through 6" of foam so on subsequent walls I switched to pre-building the bucks and strapped them into place before installing the iso. I foamed the iso boards into place on the backs and edges. What's the last 5% hurdle? Besides the grey winter skies? And Seattle's coldest winter in 32 years? And still insulating in mid-December? And running power tools all year? I estimate it was primarily inadequate ceiling insulation. I dropped one (of 3) ceilings this summer and filled it with closed cell foam (R-6 to R-40). But I still have ~ 1,000 sq/ft of ceilings with minimal (2" of rock wool in part and 3.5" of fiberglass in the other) insulation. The heat pumps are Mitsubishi with HSPF ratings of 13 so they're highly efficient but we still have plenty of heat loss. I may hit Net Zero this year (excluding car). In the future, I might install more solar panels instead of more insulation. That will likely depend on incentives, math, and spare time. My heat pump water heater accounts for 1.3 kWh/yr, or about 10% of energy use. I have all the plumbing accessible in my basement. The HPWH is already very efficient, setting a very high bar for a water heat recovery system to ever pay for itself.
Posted: 03:14 pm on December 4th 2017
"a Net Zero retrofit can be a pretty expensive undertaking" That depends on your time horizon. Paying $N00/mo to gas and electric companies every month is also expensive. I did the math and found that for about 10 years, targeting Net Zero costs about the same as the status quo. For any period longer, Net Zero is cheaper. Stated another way, I've pre-paid for 10 years of energy at today's rates, and every year my system produces after 10 is profit. But your point is well taken, the up-front costs are stiff: I dropped $15k in insulation, a $33k solar array, $15k in upgraded appliances (two heat pumps (4 heads)), fridge, dishwasher, HPWH, washing machine, bath fans, etc.). But the ROI on most of those upgrades is under 7 years. The 30% federal rebate returned a big chunk already. Seattle City Light also has a plethora of rebates for energy efficiency upgrades. The most expensive component (solar array) has a 6 year payback (details in issue #13). As Dana points out, SCL has one of the cleanest grids in the country (spoiler: hydro + wind). Rooftop solar arrays are highly complementary to our grid: in the summer when our reservoirs (and hydro production) are lowest, I'm feeding 2/3 of my annual production to the grid. During the winter when it's grey, wet, and windy and our hydro + wind peaks, I'm drawing from the grid. Everybody wins. But electricity is only 1/3 (~10kWh/year) of the average household energy equation. The average home heats with ~11kWh equiv. of natural gas and drives their cars with 15kWh equiv. of gasoline. I was looking for an escape hatch from gasoline since the Iraq war. When the Leaf became available, and it increased our automotive efficiency from ~22% to ~85%, and dropped our car energy budget from 15 to 4 kWh/yr, it was very easy to justify. Especially since Seattle's grid is nearly carbon free. That left us with natural gas. I wanted to get rid of natural gas for quite a few reasons: I don't want anyone fracking within 100 miles of my drinking water so why impose that on others?, combustion gases inside the home, gas leaks (I've witnessed 3 buildings leveled by a gas leak), old 80% efficient furnace, huge fireplace/chimney I wanted to remove, and of course carbon pollution. I don't have any baseline data for how much gas this house required because I ripped out the furnace weeks after purchasing it. But I can tell you that our entire household electricity consumption (11kWh) is about the same as the average house consumes in natural gas in this region (12kWh equiv.). The last reason to go all electric is that I'm a Tesla PowerWall away from being able to operate our entire house off-grid. That could be useful after The Big One shakes us about. I estimate the grid will be down a week and natural gas lines will take weeks to be restored. I bought a 55' truck load of 3" polyiso, as that was cheaper than buying only what I needed wholesale. I wrapped all my walls with 2 layers, gave away enough to do a friends house, and I still have 100 sheets left over. I'll probably use it to insulate my basement and crawl, just to get rid of it.
Posted: 03:22 pm on December 4th 2017
Correction: as Dana points out, my units are wrong. I reduced the kWh values but didn't update the labels. Every kWh label should be MWh. On DWRs: a 50 gallon HPWH has been quite sufficient for our family of four. I remain skeptical that a DWR is worth my time or money. "If the basement and crawlspace aren't insulated, that would account the lion's share of the remaining heat load." The majority of the remaining heat losses are the 600 sqft uninsulated slab and stub walls in the conditioned basement, the uninsulated walls in the semi-conditioned basement, and the under-insulated portions of the ceiling I haven't touched yet. Roughly in that order. Dana: "hydro production in the PNW typically peaks during the late-spring & early-summer snowmelt runoff, not during the cool and rainy winter season. The watershed areas behind the dams really count on "seasonal storage" in the form of snow, but it's locked up until the temps are warm enough to melt.." My bad. I used the term "production" when I was thinking of "capacity." BPA cares about peak hydro production because they own transmission lines and can ship the excess. SCL doesn't own transmission lines so we dump water that won't fit in the reservoirs over the spillways. To a point, because if we dump too much it gasifies the rivers and kills the fish. My point was that SCL's summer hydro capacity is limited primarily by our two reservoir systems. When SCL sees peak hydro is weather dependent and more variable than the BPA 5-year moving average suggests. Six of our hottest years on record are in the past 10. During a low snowpack year (warm, dry, or both) like 2015, peak hydro can shift MONTHS earlier to February and we saw our annual hydro lows in July and August. Even in dry years there are minimum flow rates required for the rivers. Because fish. If producing power in July means not enough water in September, then July production is curtailed. You can see that in SCL's monthly resources chart and water discharges from SCL's two hydro projects: data.seattle.gov/dataset/Monthly-Seattle-City-Light-Resources-Chart/fjv7-9qhm/data Skagit River: www.seattle.gov/light/Skagit/ Pend Oreille River: www.seattle.gov/light/Boundary/ Skagit River Water Discharge by month: waterdata.usgs.gov/wa/nwis/monthly/?referred_module=sw&site_no=12178000&por_12178000_149338=1179899,00060,149338,1908-12,2017-06&format=html_table&date_format=YYYY-MM-DD&rdb_compression=file&submitted_form=parameter_selection_list Pend Oreille Water Discharge by month: nwis.waterdata.usgs.gov/wa/nwis/monthly/?referred_module=sw&site_no=12396500&por_12396500_149573=1180131,00060,149573,1952-10,2017-09&format=html_table&date_format=YYYY-MM-DD&rdb_compression=file&submitted_form=parameter_selection_list After the 2015 drought we had record snowpacks that winter and GREAT skiing. But then we had record meltouts starting weeks earlier than normal in April '16. In May the reservoirs are nearly full so even though we had great snowpack, the early meltout caused much of our summer capacity to be lost. Warmer winters (less snowpack) and early meltouts are the trend, and longer summers means more days over which to stretch our fixed hydro capacity. I'd wager if we found a BPA hydro production graph that's six years newer there'd be a pronounced leftward shift in peak production. During those longer warmer summers, when our reservoirs are essentially a discharging battery, I'm feeding the grid and reducing summer demand. In the winter months (Nov-Mar) when I'm drawing from the grid SCL has reliably sufficient hydro and wind capacity. Enough that by December we're typically dumping water over spillways and idling wind turbines. See water discharge above. That's when I'm drawing from the grid. SCL has been a strong proponent of solar for many years. They actively support community solar projects, have booths every year at Northwest SolarFest (I got the "solar is complementary to SCLs grid" idea from an SCL employee), and contrary to my expectations, they were extremely pleasant to work with while getting my array deployed. Solar is also complementary to SCL's grid in another way. We're (SCL is city owned) buying solar power from California (during the day, when prices are free or negative) and then selling our hydro power later in the day when prices are [much] higher. sccinsight.com/2017/05/21/seattle-city-light-join-energy-imbalance-market/ "Seattle City Light's resources will have a similar profile, so your PV production is really peaking about the same time as hydro production, give or take a month. Your PV output peak in Seattle may actually be in April or May most years" In May and June most mornings are overcast with chance of rain, burning off by mid-day. Then summer arrives on July 8th. The clouds depart and the rains finally stop. My monthly production for 2017 (kWh): 228, 337, 547, 929, 1250, 1370, 1640, 1310, 904, 493, 163. I peaked in July and my actual production nicely correlates with PVWatts predictions for an East-West facing array with an 18° pitch.
Posted: 03:43 pm on December 8th 2017
HRV vs Exhaust-Only Last year I completed a Deep Energy Retrofit on my 1955 home. I considered (because my contractor friends mentioned it, often) an HRV. I decided to try the exhaust-only approach first. If it proved necessary, it would be easy enough to add a make-up air damper or an HRV later. Part of the DER was replacing the old single pane aluminum windows and adding 6" of polyiso insulation all the way around the exterior. As I did that, I foam and/or caulk sealed all the gaps, cracks, and holes from the foundation walls to the rafters. I taped all the plywood seams and foamed and taped all the polyiso seams. On the framed floors, I sprayed an inch of foam under the subfloor to air seal before filling the joist bays with batts. On the one ceiling I took down I filled the rafter bays with closed cell foam, air sealing them. I removed the chimney and all the combustion appliances and forced air ductwork (so...many...holes...plugged!). My exhaust-only ventilation system is powered by a Panasonic WhisperGreen FV-05-11 (50-80-110) in both bathrooms, a WhisperGreen FV-11-15 (110-130-150) in my basement (for humidity control and when I'm using the basement as a paint booth), and a Z Line GL14i-30 range hood (280-400-580-760). The bath fans are motion activated and remain on for 30 minutes after motion stops. One fan is set for 50cfm and the other is set for 80. With a family of four present, at least one bath fan is typically on during most waking hours. The other two fans are operated manually. I haven't done a blower door or even a garbage bag test but I roughly gauge the building air leakiness using a piece of yarn and a cracked window. (Fun fact, when working in a wind tunnel, we used to use yarn or dental floss to guesstimate air velocity. It takes a while for a wind tunnel to get up to speed, so watching the yarn and eyeing the gauges while working lets you get a really good sense for how the string behaves at different air speeds. Once you can guesstimate velocity, you can multiply it by area to get flow. With a single bath fan operating (50-80cfm), cracking a window produces negligible yarn motion. If both fans are going, there will be a slight breeze through the cracked window and the yarn will bounce around. The kitchen fan at its most commonly used 280 cfm "1" setting exceeds my "gaps and cracks" makeup air. The yarn in the cracked window will hang at an angle. We're in the habit of opening a door or window any time we use the range hood above level 1. The bath fans alone are almost sufficient to meet "ASHRAE 62.2 – 2010" calculated 53 cfm. While I don't have them operating continuously, their use is correlated to occupancy and they often run concurrently. They seem to run enough. If I were to drop another ceiling and air seal (and super-insulate) it, I suspect I might finally need dedicated makeup air. In that case I'd likely add a makeup air damper on a pressure switch. That's a much simpler and cheaper solution than an HRV.
Posted: 02:24 am on February 2nd 2018
net zero on 4k blows my mind Hitting Net Zero with only 4MWh of annual production seems really really optimistic. My electric car (Leaf) uses 3.2MWh annually! My GE heat pump water heater with a 3.25 Energy Factor is rated at 1.3MWh/yr (no meter for it). And you've still got heat pumps, fridge, dishwasher, ventilation, and laundry machines to power. In 2016 I deployed a 9.8kW array. In calendar year 2017 my array produced 9,288 kWh. The average household in this region has an energy budget of 22,000 kWh/yr and so I was quite proud when we used just 9,180 kWh and achieved net zero. If you can hit net zero with just 4MWh/yr of production, I salute you and yours, good sir. That would be remarkable. Comparisons: my house was build in 1955 when energy conservation meant asking someone else to grab you a beer. Seattle has 4,700 heating degree days compared to your 5,500. My house is 2,300 sqft, so 38% larger. We have four occupants (1 more). We have all LED lights, power strips normally off to kill parasitic loads, all EnergyStar or better appliances, R-36 outside-the-sheathing insulation, spray foam and air sealed portions of the floor and roof, new 0.19 low-e windows throughout, air sealed like a madman while adding the aforementioned insulation, HPWH, low-flow (but not too low) faucets and fixtures. Many thanks to GBA and Building Science for much of the wisdom, knowledge, and inspiration.
Posted: 04:34 pm on February 7th 2018
Home owners manual I know exactly what would happen with a home owners manual while/after I'm gone: nothing. The reason manuals don't follow the home to the next owners is because the previous owners have no idea where to find the manual(s) because they've never read or used it! Just like the manuals for their cars and their [VCR/DVD/oven/other appliance] which blinks 12:00 until someone else visits them. I'm all for EVERYTHING Martin recommends in "Simplicity versus Complexity" except the house manual. As a mechanical engineer by training, and a software engineer by vocation, and a writer of much documentation, I'm a real sucker for great docs. I have every manual for every appliance in my home and they're all together on my bookshelf. I'd also wager that anyone reading comments on GBA also appreciates good docs, but we should also be realists and harbor no illusions that anyone else will ever care about those manuals. So why spend time assembling a binder that nobody else will ever open? Instead, a single page checklist of maintenance tasks, fastened permanently to the wall or the backside of the door of the utility room has a greater likelihood of being seen regularly and acted upon. every time: remove lint from dryer trap bi-monthly: remove, rinse, and replace water heater air filter bi-monthly: make sure no error lights on water heater annually: pour a 5-gallon bucket of water into the sump bucket and watch it get pumped out January: rotate mattresses 180° July: rotate mattresses 180° August: rinse and replace air filters for 2 upstairs heat pump heads December: rinse and replace air filters for 2 downstairs heat pump heads
Posted: 05:30 pm on February 7th 2018
less grid dependence?
and deliver that heat at a later time while decreasing my dependency on the grid. I think we can all agree that the system does achieve that goal.With your system the majority of your heat energy is non-grid while the majority of your heat distribution energy is very grid dependent. During a power outage, is the heat energy that would normally be heating water lost up the chimney? At first blush, this seems only slightly less "grid dependent" than burning fossil fuels with a typical forced air distribution system. The difference is that the remaining direct heat will likely suffice for a Passive House during a grid outage.
Posted: 01:07 pm on June 20th 2018
Your heating contractors performed their manual J calculations based on how your home currently is. How well insulated is your home? If you first spend $2-3k on insulation, you could instead install a smaller 2-ton unit. Then you will likely spend less on your geothermal system and you'll get the benefits of adding insulation: lower energy bills, increased comfort, etc. I'd go back and ask your contractor(s) to perform their manual J calculations with anticipated levels of insulation.
Posted: 01:30 pm on June 20th 2018