Ooooh. Didn’t know “they” made these. I assumed I could have a SIPs manufacturer make them though. Just didn’t know they had a name.
It pains me to say it, but our house is for sale.
We love love love this place, but the daily carpool/commute to our kid’s school in N Framingham is killing us. It’s 17*4 = 68 minutes in a car. When it could obviously be 5 or 10 if we lived closer.
So inquire quickly if you are interested! It’s been on MLS for only a day and we’ve already had several pings. google: 147 N Shore Dr, Stow MA 01775
The basic ideas of the house is:
- IAQ (indoor air quality)
- Comfort (living with no drafts and even air temps is an amazing experience)
- Daylighting. All of our rooms (including our bathrooms and basement) have nice daylighting.
- *Insanely* energy efficient (we EARN over net $1100 on our utility bills due to solar SRECs)
- Durable (little or no maintenance needed… hardiplank siding, hardwood floors, etc)
- “Passive Survivability” (I like that we can lose power and not worry about the house getting too cold very quickly or pipes bursting)
- Someday… homestead. There is a LOT of space in the front (S) of the house for a suburban vegetable “victory garden”. If we were more ambitious, I assume we could easily grow all our veggies.
I’ll follow up soon with some photos…
There are many in green circles — superinsulated/zero energy home/passivhaus circles — who think that heating with electricity (ideally with an air-source heat pump) is the ideal way to heat a house with solar electric (PV) panels on the roof (well, or yard). Example link
As someone with a house that is exactly that, let me chime in.
Heat pumps: PROS
1. No hole needed in house for exhaust or air intake
2. No air-quality or safety concerns since no burning of wood or fossil fuels in the house
3. Math is easy if you are trying to be net-zero. If everything is electricity, then there is no complicated math to do converting gallons of propane or cords of wood burned into KWh. (not much of a reason)
4. Now you have AC too. OK, so you saved a few bucks. Window ACs are only $80 though. And you house probably doesn’t need much more than one of those. Really.
5. No baseboards taking up space. But there are other approaches (forced hot air and such) to deal with that.
6. Quiet inside. Wow, very very very quiet. No furnace, furnace fan, or boiler making a racket. (Aside: And no humidifiers in winter… thanks to the tight superinsulated house part…)
7. Electricity tends to be price-stable vs the price of propane and heating oil which seems to whip-around a lot.
8. Usually a bit cheaper to install vs a “central” system esp in a very small house. But add in the price of the HRV or ERV stuff if you have that too.
9. Point source: I list “point source” below as a con too. Some like point source heat since it allows zoning, getting cozy by the “fire” and such. Flip side to everything.
10. Future safe. Electricity can come from many primary sources.
Heat pumps: CONS:
1. Can be a bit loud outside (well not LOUD, but there is a fan running, like for central air-conditioning, all winter) So if you are noise sensitive maybe there is a quieter heating approach? Not sure what qualifies as the quietest. Radiant floor heat?
2. PVs should not be thought of as anything more than an offset in my opinion. Don’t think of that electricity your panels made as yours. Who cares WHO uses it. The point is to reduce CO2/greenhouse gases overall. In other words, if you make electricity, dump it into the grid for your neighbor to use, and burn some wood to keep warm instead, then you are ahead (in my eyes) of someone using that electricity directly to heat their house with a heat pump.
3. In very cold areas, you will need either a HYPERHEAT model that keeps up with sub-0F temps, or some back up (maybe electric space heaters). Most other air-source heat pumps drop their output by a lot when it is VERY cold.
4. Power outages. You will have no heat. Now, that might not matter as much, because your superinsulated house has a certain amount of “passive survivability” built into it with all that insulation, but if we are talking comfort here, then grab a wood stove or a propane heater needing no electricity to run. There are a few!
5. “Non-traditional” Looks: Some might think they are ugly. I don’t mind them. Just different. And controls. Our Mr Slim one has a “remote” vs a traditional thermostat. And the model we got doesn’t control all 4 internal heads. So like a house with zoning, you have to walk around and set each individually.
6. Point source: We have 4 of these inside “heads”. One on a wall on each floor (basement, 1st, 2nd, 3rd (attic)) But there is not heat/coolth pumping into every last room. Doesn’t matter much, but bedrooms are a little cooler — 5F? Coldham/Rocky Hill study seems to say. Ask google.
2. Carbon neutral
4. Simple technology (especially if not pellets and not catalytic)
5. No electricity needed (heat when power outages)
Wood Stoves: CONS
1. Lugging stuff
2. Might be difficult to vent properly in a very tight house. Indoor Air Quality risk. Especially with a pellet stove which loses electricity.
3. Even the smallest pellet stoves will overheat some houses that are superinsulated. But big whoop. Run it on thermostat-mode. And open the window if you must!
4. Particulate pollution. You might live pretty near other people or in a town or city that prohibits wood burning.
5. Related… Gotta know what you are doing. (slow-burning, smoldering wood stove fires pollute like crazy and smell up the neighborhood.)
Solar Thermal Heating: MIGHT BEAT WOOD IF…
1. You have sun
2. You have a spot to put the solar thermal panels and a HUGE 1000 gallon tank in your basement
3. You have already done energy efficiency fixes — insulation, CFLs, etc. (see builditsolar.com)
4. CON: Up front cost is going to be higher than the wood (at least a pellet stove vented out the side of a house) unless you are a DIY person (see builditsolar.com)
Prius: PROS (W/holistically speaking, maybe this is a better place to start…)
1. Do the calculations in KWh. If you cut the number of gallons of gas you use in half by driving a hybrid or electric car, how much is that in KWh?
2. Energy Independence: coal and nukes (for making electricity) are “local” to the US, vs gasoline comes mostly from other countries. Propane is 90% from US. Natural Gas is ???
3. Use as a backup generator for house
So what would I do?
Well right now we use an air-source heat pump to heat our almost passivhaus ZEH. But I hope to do more solar-thermal heating in the future. 5 days of storage would get you to 97% solar “if cloudy days are like coin flips”. And the no-electricity propane heater is intriguing, especially for a little backup. Check back in a year!
We agreed to let Fraunhofer add little sensors to EVERY plug in our house. It’s a pilot program that Lawrence Berkeley National Laboratory is running Miscellaneous and Electronic Loads Research. It will report usage every 10 seconds from every plug back to the interweb via UDP
I am trying to imagine what useful information could come out of this for the greater good, and I can’t quite come up with anything. Perhaps they will be able to use the detailed data to disambiguate data coming from a single smart-meter on a house. (like Google Powermeter) In other words, being able to tell “oh, that’s the fridge coming on” vs “oh, someone turned on a light” or “that’s the dishwasher”. Who knows.
On a personal level, I probably won’t learn anything… but that’s totally fine, I am happy to help! I have pretty much figured out anything I wanted to know via a Kill-a-watt and the eMonitor/TED 5000 approach of “circuit” level monitoring.
I suspect it would be better to “follow the money”. I bet people (in New England at least) spend a lot more heating and cooling their house than they do on phantom loads from electronics and leaving lights on.
Both are worth doing I guess. Like Gary did with his “half” plan.
When we built our house we decided to have an Energy Star rater calculate the HERS score for the house (11 was it? 12? Not that I verified that they used the right numbers for our insulation, etc, but OK, not bad.) And part of the Energy Star Homes process is that a blower-door test is done to determine how leaky the house is. Since that’s the other way one can lose heat/coolth from the house. Not just thru walls and windows and doors, but from actual airflow thru all the cracks.
Well anyway, our house is quite tight. It was 200 CFM50 which works out to
200 CFM50 * 60 min/hr / (2310 sqft * 8.2 ft/floor) = 0.63 ACH50 (air changes per hour at 50 pascals)
I don’t know if I’m using quite the right volume for the house (that’s 2310 including basement) but if so, that is JUST shy of the 0.60 ACH50 needed for Passive House certification. Nice. We’re probably a bit worse than this, but really, I can’t complain given we are using mostly double hung windows and double hungs don’t seal up as nicely as casements.
It was the tightest house the Energy Star person had tested in 10 years or so of blower-door testing. I believe our house is apparently what is called a “Tier 3″ / “Tier III” certified home for Energy Star Homes.
In New England, I reckon we are one of about a few dozen or so such energy efficient homes. Something like that.
Here’s a list I am compiling. More at the NESEA.org Green Buildings Tour website I am sure.
The idea of Building Tight is that it is actually better for
- indoor air quality
- saving money
Durability: fewer mositure/mildew/rot problems because there is little concern with
1) moist summer air driven from outside to in
2) most winter air (since outside is very dry) being driven from inside to out.
Indoor Air Quality: Instead of relying on leaks in a closed up house (in winter or summer) to provide fresh air, one can bring in exactly the right amount! And filter it to your heart’s content! And put it right where you want it!
Saving Money: The idea is this… in the winter for example: instead of 68F air exiting the house and 25F air coming in…. thru leaks… one can instead use an HRV (heat recovery ventilator) which is essentially a fancy air-to-air heat exchanger. The incoming and exhausting air cross paths in a fancy cross-woven area and 60 or 70% of the heat that would be normally lost is recovered and plunked into the incoming air. Clever! One has to factor in the cost of installation and running the fan, but the fan costs almost nothing, and the control over the IAQ and durability is worth it.
Some others recommend slightly different approaches:
- not building QUITE as tight (but still 10x tighter than a typical house)
- using Panasonic Whispergreen bathroom fans on timers or humidistats or CO2 monitors to do “exhaust only” ventilation.
Lots more on this topic over at greenbuildingadvisor.com — free blogs and Q&A sections. I sound like an advertisement I know. Sorry, it’s a very helpful site!
After recent monthly electricity bills of $0.68 and $3.61 (or whatever the exact numbers) this month the electricity bill went WAY up. $26.21!!! We still had quite good numbers on the PV production side, and didn’t use much, but since there is no net-metering (our electricity supplier is a municipal and so is exempt from the MA law requiring that electricity companies allow net-metering for grid-tied PV and wind systems. I’m not really complaining, just explaining.
So anyway, our billing is “time of use” so any time the sun isn’t shining and we use electricity, we pay for it full price whereas when we have extra on sunny days that we put back into the grid, we are paid back for this on $0.44550/KWh (roughly 3 or 4 times less than what we pay).
So that’s basically how we end up with a $26.21 electricity bill even though we put 571 KWh back into the grid and only used 381 from the grid.
If there was net metering I suppose our bill would be something like:
571-381=190KWh extra made, so…
Min charge from the electric company is: $21.63
- 0.15 x 190 (the rough amount paid per KWh is 15 cents)
= 21.63 – 28.50 = -$6.87 (credit)
I guess one could calculate the amount this will likely add up to over one year. Rough assumptions:
1. Exactly net-zero for the year
Our PVs make exactly the amount expected from the “avg year” from the “PV Watts v1″ calculator on the web (I believe it is ~9000KWh for our 6.9KW PV system)
2. Worst case scenario: we use exactly 0 KWh of our electricity we make during the day — everyone is away and somehow the house magically uses nothing in phantom loads (impossible since the smoke detectors have to run at the very least!) — and therefore we have to buy 100% of our electricity (at night).
If net-metering, our bill for the year would be exactly $0.00. Simple.
With our current arrangement it will be (worst case) per month: $21.63 + 0.15 * (9000/12 – 200) (Note: -200 since 200KWh are included in the $21.63 monthly base charge and we will likely always use at least this much in eves)
That’s per year = 12 * 134.13 = $1609.56
In reality it will be much less than this because we DO use a lot of our electricity during the day. So let’s say 1/2 that… $800.
$66 per month.
And that’s for everything, heating/cooling (heat pump), all appliances, cooking, hot water (also heat pump), mowing, well pump, etc, etc.
Anyway, I’ll report back in a year with the actual numbers.
Review: Mike Marquis is the finish carpenter who did the finish work on our three flights of stairs in our house in Stow, MA. He also installed our kitchen cabinets. He is a meticulous craftsman! I could imagine it might be difficult to find good people who do good work so here is my advice: Highly recommended! Mike works in Massachusetts, the Boston area, and in Southern New Hampshire on a variety of projects and I would highly recommend you consider him for any type of finish carpentry work including custom projects. More at his website: michael marquis finish carpentry His phone: 603-759-1198
We are nearly done with our house construction and basically done with any of the details which will affect the results of our house’s “performance” and results of our analysis using PHPP. (PHPP is the software… a gigantic excel file… used to help design and analyze the expected energy use of a planned or existing house.)
So a few comments about passive house / passivhaus.
There are some people who think the passivhaus requirements are too difficult for new england, the upper midwest, and maybe pheonix I’ve heard (on the heating end of the sprectrum). But I personally disagree. If people want to live in extreme environments, then I see no reason why they should be let off the hook.
What I would say, is that it really is quite reasonable to take an 80% or 90% approach. Well, or 50% is good too! In other words, if one can get to within 90% of a passivhaus, then gosh, that is quite an amazing house you’ve got there. Getting all the way there is trickier in harsh climates. That said, I think it is a valid complaint that there are a number of very low cost things which people can do when building or renovating a house that people just don’t do and also that one can think “I’m going to do some PH things, but not all” and think you are going to get very close (let’s say 80% there) but in reality… you are only 40% there if one ran the numbers in PHPP and monitored the actual usage. So that’s a shame too. Valid point.
And also in the US … it’s harder (more expensive) to get the HRV/ERV and windows one needs. I say that, but perhaps it’s not so bad. Maybe the high VAT (sales tax) in many European countries means that effective prices aren’t THAT much higher here for a fancy window imported from Germany for example.
However, I still wish we could do things more locally.
I guess what I’m saying is… I think there is a place for:
1. People going all out and meeting PH with imported products and maybe some non-typical building products or techniques (this helps informs builders and future custom home or renovators to what is possible) . We need people to push on the edge of what people have done before so we can learn.
2. Sticking to only what is in a typical budget but nailing all the “low hanging fruit” — the cheap stuff. It’s a no brainer and not expensive to build a tight house and one with 2-3 times more insulation (using dense packed cellulose). And there are some quite good and not that expensive triple pane windows out there (like Paradigm in ME).
3. Somewhere in between… using PHPP to analyze, and monitor the house, but don’t go all the way with imported products. This is still great because it helps to validate the PHPP software as a accurate model of “reality”.
4. The usage of a house matters a LOT. If you aren’t careful with electricity usage and hot water usage… it’s been found that people can easily use 2 or 3 times much as another similarly sized family (I’m pretty sure I’ve seen analysis of this with comparably built homes and family sizes at cohousing developments.)
5. I think of PVs (solar electric panels) as an offset. Especially if you have net-metering, it shouldn’t really impact one’s choice of how to heat the house or hot water. IOW, prices being equal… it’s not really any better to use a air-source heat pump that 98% efficient propane hot water heater for heat. That’s based on average utility company mix of using mostly fossil fuels. If you have hydro or a “green up” option on your bill, I think the balance tips to the heat pump approach.
6. Holistic thinking… OK, so nice house. Do you eat meat? What MPG does your car get and how many miles do you drive? These things matter a lot too. Especially relative to a house operating very efficiently. A vegan driving a Prius (or living in the city and walking) maybe has a smaller carbon footprint more than someone living in a small passivhaus. I don’t know! But it’s not too hard to run the numbers. Gary Reysa at builditsolar.com does this. See his “half” project. Marc Rosenabaum at energysmiths.com does this if you are designing a house or cohousing community or fixing up an office building or dormitory, etc.
If I buy a lot of stuff and fly in airplanes a lot, my passivhaus doesn’t matter so much any more.
7. Related to #5 above… I also think “Zero Energy Homes” are cool too. I mean, zero is better than not zero. A passivhaus can more easily become a zero energy home because there is less usage to offset with PVs. And not everyone has a sunny climate or a sunny lot. And insulation doesn’t break or wear out (if you build it right). Whereas solar electric panels (PVs) do.
8. Burning wood is good. Solar is better obviously, but come on… wood is very good too. So is a greasecar (modification to run any clean TDI diesel using used vegetable oil). Not as cool as a hybrid, but in the end, who is using more fossil fuel? The hybrid!
9. I’ve said this elsewhere, but we are right about at the point that without even factoring in tax credits, etc… a grid-connected solar electric system on a sunny roof is cheaper than paying electricity bills. Prices have come down quite a bit. At least in MA with net metering and high electricity prices.
10. If it’s energy independence that you care about most, improve your car first (or if you have oil heat). Coal etc is not primarily coming from other countries.
If you like math, you can compare all these things! It’s all just BTUs and KWhs and some arithmetic and adding things up! PHPP is really just an incredibly detailed version of this same thing (for just the house).
So let’s all get to 80%! That’s way better than a few going all the way and everyone else feeling put off or excluded because it’s too expensive.
Ya know how if you have junk food in the house… you eat it? So best to not buy it in the first place? Well, we’re going to try the same thing with our house in two aspects — no exterior venting of our (electric) stove. And no clothes dryer (we’ll see how that works out! We’ll probably have our old one, just not plugged in, and we’ll sell it if all works out…). Health first obviously. Saving energy is a distant second…. so first and foremost this has to make sense from a health stand point. No internal combustion in the kitchen (electric range), so no need to vent out carbon monoxide (CO) from combustion. And clothes drying… no health issues there, except that we obviously need to keep humidity levels in check.
Well so the problem with both of these types of holes/vents in a house in the first place is that there would need to be an equal amount of make-up air coming IN to the house from another source, and since our house is quite tight, that might be kinda tough to get it via leakage as in most houses. (Our house tested at just above Passivhaus tightness levels, and this was the first blower door test before drywall… so we will be even a little tighter probably.) And the basic point that you are venting out conditioned air, and bringing in cold (or hot in summer) air in exchange. So that’s a waste.
On the other hand… it’s also a bit of a waste to be cooking with electricity (vs propane or natural gas) as it takes 3 times the amount of fossil fuels at the power plant. But I believe I’ve done the calculations, and given the fairly low efficiency of gas ranges, the numbers don’t work out to be quite so bad. And some money savings, since no need for “dual fuel” to get an electric oven out of the deal.
Anyway, back to clothes drying. Our clothes already come out of our washer almost dry actually (front loader) so hanging them on a drying rack, even right in the house, should dry them out rather quickly. If need be, a space dehumidifier can help with moisture levels. Or we will stop being lazy and hang clothes outside. Imagine that! See this building science article on latent vs sensible loads. Basically the issue of “how do you dehumidify when you don’t need cooling?” BSI-028: Energy Flow Across Enclosures especially “Photograph 6: Hotel Room Fix—The through-wall unit controls the temperature (the “sensible” system). The dehumidifier controls the humidity (the “latent” system).”
Others will say that this (0.6 ACH) is excessive tightness, and something more like (2.0 ACH) is still plenty tight but would alleviate issues with make-up air. And maybe at that level an “exhaust only” ventilation system would work with no need for a HRV or ERV. Maybe. I think there are smart people on both sides of this issue. Let’s check back in 10 years and see what people think? My current thinking is KISS — keep it simple stupid — so if there is a way to do this with less complicated and more local methods (less complicated HVAC equipment, cellulose-only insulation instead of spray foam) etc, then that’s a more sustainable gameplan ultimately. Better for the environment and the local economy. Another way to put it is I’d rather spend money on people doing work than on expensive equipment. That said, I also prefer negawatts to megawatts. So let’s aim for both of these… local and negawatts!
[Update: I should have explained one thing better... There IS a range hood with some fancy grease filters, but it does recirculate. And there IS also an exhaust duct for the HRV in the kitchen. And an operable window right behind the range. We are basically following the approach used in Passivhaus construction to use a recirculating hood and a HRV exhaust duct nearby but not directly connected. We'll see how it goes. We can always add an outside vented range hood but thought it would be good to at least try this since it apparently works fine for 1000s of passivhauses in Europe.]
The house we are building here in lovely Massachusetts, USA… almost a Passive House, but not quite certifiable… well, we can heat it with a hair dryer (1500 W of heat). And two on a very cold day (6F design temperature). Does this mean our heating bills will be low? Pretty low, I imagine, yes. But not zero.
Let’s do some math… And first let’s simplify things… the HDD (heating degree days) for Stow, MA is somewhere around 7200 (base 68F) meaning that if you multiply the days of the year we need heat times the temperature differential between the inside and outside temperature on these days, you’ll get 7200. It’s a little more exact than this (think “area under the curve” from calculus — using hour by hour measurements), but that’s the basic idea.
So let’s simplify it even more. Let’s call every winter day exactly 32F outside vs 68F inside and assume our 1500 W can keep up with that (which from my back-of-the-envelope calculations seems about right…) So that’s a delta of 36F. Now how many days is that? 7200 F*days / 36 F = 200 days = 6.66 months. Let’s go crazy and call it 7 months.
OK, so let’s say one really did run a hair dryer for 7 months, 24 hours a day. What would that cost to run 1500 W (1.5kW) that whole time? Well, we pay $0.20/KWh. So using the factor-label method to keep track of our units… making sure numerators and denominators cancel out, that’s:
7 months * 30 days/month * 24 h / day * 1.5 KW * $0.20 / KWh = $1,512.00 per year
In other words, kinda a lot!!!!
But that’s why people don’t typically use electric heat, it’s expensive. (It’s also not a great idea because fossil-fuel power plants are roughly 33% efficient in converting the fuel to electricity… I imagine that’s exactly why it’s expensive! So… it’s better to use it in direct form at your house…) That’s where the heat pump comes in. If we factor in the 2.7 COP (coefficient of performance) of our Mitsubishi “Mr Slim” air-source heat pumps that’s:
$ 1512 / 2.7 = $560
OK, now we’re talking! This also happens to be almost exactly the number you would get if you calculated the cost of delivering 1500W of heat via propane or natural gas. That would be fine and dandy too. So the 2.7 COP mainly serves to green up the electricity use, getting back to parity with using propane directly. 2.7 * 0.33 = 0.8991 (probably about the efficiency of a Rinnai propane direct-vent heater)
Now, the reality is that I hope most of this heat comes from active solar heating. But more on that later!