Category Archives: superinsulation

If you are pondering indoor air-quality…

If you are pondering indoor air-quality in your home… I urge you to look into the issue of flame-retardants in furniture — specifically in the foam used in mattresses and couches.

Here is an upsetting recent article on the topic PBDEs and chlorinated Tris (I knew about PBDEs, but hadn’t considered that (DUH!) the replacement would probably be just as bad or worse. And that they don’t even work!)

Some good practical advice here (if you are a millionaire)

Leave a comment

Filed under corporations, erik-green, green, health, HVAC, IAQ -- indoor air quality, passive house, science, superinsulation

New house? Changing exterior door knobs? — use levers

Are you building a new house or fixing one up — passivhaus, zero energy, or otherwise energy efficient to some degree? Some simple advice: Use levers not knobs. At least for the exterior doors since those are the ones that are going to be sealed up tight with gaskets and such. And also since your house might be quite tight, especially in the winter when all the windows are closed… you are pushing/pulling against this “vaccuum”. So no draft, but the door is also a little harder to open and close.

Maybe not noticable for an abled adult, but it is noticable if you have little kids. Yes, you say, but turning the knob/lever is different than pushing/pulling the door open and I am only changing the opener not the gaskets. But I am telling you. FROM EXPERIENCE… they are related!!! My 4 year old cannot easily twist the knob and simultaneously push/pull our exterior doors open. I think if they were levers (like a storm door we have)… it would be much easier.

To me this is both a safety issue and a respect for children issue. And you’ll be happy too (and guests) if you are maybe older or injured and are having trouble with the knobs. General “accessibility” I guess the word is.

I’ve heard levers are better. It’s now obvious to me that this is quite correct and important and not to be ignored. Do it!

Leave a comment

Filed under green, kids -- freedom and responsibility, passive house, superinsulation, zero energy home

2011/12: The year in heating

We have an emonitor gizmo that tracks our home energy use by circuit. One circuit is the air-source minisplit heat pump (the heat and cool in the house).

For the YEAR ending April 2012, the heatpump circuit shows:

3,009 KWh (total for year, heating and cooling and some hot water)
2,598 KWh (Oct-Apr — 7 mostly heating months)

Remember that we also heat our water with an air-to-water heat pump in the conditioned basement, so during the heating months, it is stealing heat from the house. So the 2598 includes some of that. Let’s pretend it is 10% of our total load (no idea) so that would be

2338 KWh (Oct-Apr — mostly heating months. HOME HEATING ONLY)

If we pretend the price we pay for electricity is $0.15/KWh (it’s more complicated than just a simple number like that with this and that charges) but close… then that is:

$350.70 (our estimated heating bill for winter 2011/2012)

Nice.

(Well, and actually… minus some significant fraction of that which is covered by our PVs (electric solar panels). We don’t have net metering, so our electric bill is rarely $0 even in the summer. I just don’t unclude the PVs cause I generally think of them as an offset. Not an important part of the house.)

SMALL IMPROVEMENTS “FOR SOMEDAY”:
– The silly 20KWh/month our minisplit uses whether it is on or not. Nothing to do about that at least in the winter. But I could flip the dip-switch for 5 months of the year.
– Someday I will add a submeter for the minisplits since the emonitor is probably 10% off in some direction. (I believe that’s the spec I’ve seen.)
– More PVs, perhaps this string with a central inverter and small battery for:     – night-time (since no net metering) and
    – power outages (we have a well so it would at LEAST be nice to have running water when the power goes out.)

Leave a comment

Filed under energy, energy-efficiency, erik-green, HVAC, passive house, superinsulation, zero energy home

We’d be net zero but…

Our house would be net zero source energy but…

- well filters: we avg 54 KWh / month
– well pump: 10 Kwh / month
– radon fan: 40 KWh / month
– 2 home offices: 60 KWh / month
– Mitsubishi minisplit: 20 Kwh / month (EVEN WHEN OFF DUE TO A COIL HEATER THINGY!)
– electric lawn mower: (not much, but just sayin’)

What else did I forget?

TOTAL:
So that’s 54+10+40+60+20 = 184 KWh / month
= 2208 / KWh per year

… that we can’t help that some other net-zero types of house don’t have since our house has a well and 2 home offices and a mitsubishi mr slim air-source heat pump with what I would consider a design flaw!

We use approximately 10,000 KWh per year for everything (heat, hot water, lighting, cooking, etc.) And our 6.9 KW PV panels make about 8,400 KWh so if we didn’t have the extra 2200 KWh, we’d be easily net zero.

BUT… then there is driving. Someone who lives in a city in and walks everywhere is blowing us away. We drive maybe 15000 miles per year at 20 MPG (minivan). There goes net-zero.

Leave a comment

Filed under contrarian, energy-efficiency, erik-green, HVAC, passive house, superinsulation, thinking, zero energy home

Overheating, Passivhaus Style

One limitation of the PHPP modelling used in the Passivhaus / Passive House certification process is that the only kind of solar thermal heating which is modeled is windows (passive solar… BTW, not to be confused with “passive house”… 2 different things!) and not fancier (active solar) stuff with anything movable insulation and/or small fans and/or externally located solar-air-heaters like:

1 – commercially available solar air-heater SolarSheat or Sunmate (great example here)
2 – low-mass thermally isolated sunspace ala Nick Pine / Norman Saunders / William Shurcliff
3 – “solar siding” ala Nick Pine (essentially a very large solar-air heater, kinda like SolarWall or solar tempering)
4 – DIY downspot heaters ala Scott Davis
5 – a solar “yard furnace” ala Nick Pine (see messages in the SolarHeat yahoo group — always free membership required).
6 – Commercial or DIY solar water heating used for heating (via radiant floor heating or an water-to-air heat exchanger)

OVERHEATING RISK

So the only thing you can do in PHPP is (in New England) optimize the windows for high SHGC (for the winter-time gains needed, winter being the main energy hog here in 2011) and add overhangs (ideally movable, like a trellis of greenery) or exterior shades (like they used in switzerland and france) to deal with the summer risk of overheating (since it still gets hot and sunny here). Also problematic for overheating are periods of the fall and spring when the sun is still low and leaves are not on the trees but it’s warm outside. Yes, you can open the windows. That will help a bit. Yes, you can install a concrete floor. That will help a bit to even out the swings, though it’s slow to react. But this is what Nick Pine and others like to call “living inside the heat battery”. Temps swing around a lot and you have little control over it besides turning on the heat or AC or moving shutters and insulating shades and such around manually. If you have the time.

A better way is keeping the solar collection on the outside of the thermal envelope of the house and optionally automatically store some for later in a huge highly insulated water tank in the basement (though that gets more complicated and/or expensive) (Getting close to 100% solar heating means being able to get thru quite a few days of no sun, so do your BTU/KWh heat load and storage capacity calculations over at the SolarHeat yahoo group.)

Advantages:
1. You can have pinpoint control over how much of that solar heat you let into your home!
2. Not blinded by all the light pouring thru lots of windows
3. Not as limited in architecture. Want bedrooms to the south but not wanting light blocking shades, etc, etc. Bad view on the South? Just add a huge air collector… no windows needed!
4. Easier to add solar heating existing homes/retrofit

So back to the overheating. To summarize the reasons to think carefully about cooling/preventing overheating in a passivhouse or otherwise superinsulated home:

1. too much passive solar. Big windows on S with high SHGC and no overhangs? Look out!

2. point source cooling on first floor (A BE2012 presentation about the VT Passivhaus by Habitat for Humanity detailed the warm 2nd floor)

3. warm bedrooms in summer. (related to point 2). bedrooms are often on second floor. If you are using air-source mini-split heat pumps to heat/cool your house and there is not an inside head in a bedroom, then guess what… on those summer nights when it doesn’t cool down outside and you need to keep the windows closed, it’s going to get warm in the bedroom… you’ve got 300Watts per person and warmish air coming in thru the fresh-air ventilation system (HRV or ERV) and how is it going to cool off? That’s right… it’s not. People should worry A LOT about this. Winter time is no problem with point source heating downstairs (or down the hall in our case). It’s a tad cooler in the bedroom, but the body heat — 300W per person — helps mitigate. Plus most people like it a “little” cooler for sleeping.

4. Global Warming. Not to get too pessimistic, but some scientific predictions are than NH weather will be like NC in 30 years. LINK. And Southern VT is already like PA in the 1960s. Yikes. It’s worth considering!

That said, the basic idea of worrying more about the heating load than the cooling load in New England and the midwest is a valid one. There are many many more HDD (heating degree days) than CDD (cooling degree days). So optimize for heating first. But have a cooling plan too! It still gets very HOT AND HUMID in Massachusetts and Minnesota!

Also not allowed in PHPP is counting PVs as a solar hot water heater. Instead of buying an expensive and complicated traditional solar hot water heating system that still might only provide a 60-70% overall solar fraction for the year, I explored building one myself for $1k and ultimately decided to just increase the KW of our PV (solar-electric) array to meet the hot water demand (I calculated) a full 100% (net for the year). Marc took the same route described here.

I am of course very open to correction on my assessment of the current state of the PHPP (circa 2010-12) with regard to solar.

Leave a comment

Filed under contrarian, erik-green, passive house, simple, solar, superinsulation, zero energy home

Small houses for families or multiple families WITH KIDS

Get real people.

1. It’s a mess out there. I believe I read recently that there has been a substantial percentage increase in the number of families doubling up — Kids (and families) moving in with parents or grandparents. Duh!

2. All the small home books show houses typically designed for a couple. Or maybe one neatnik toddler. And that’s it? The (sole?) exception being Little House on a Small Planet, 2nd: Simple Homes, Cozy Retreats, and Energy Efficient Possibilities
I liked that book.

OK, so what makes a small house design workable when there are 8+ people (especially with kids) living under that one roof? This post will collect my ongoing thoughts on the topic.

Topics to be expanded upon someday, perhaps. Biased toward northern homes:
– design patterns. loops are important with kids. this is counter the idea of getting rid of wasted hallways spaces but I have thoughts on that. (Namely, do it anyway, a little)
– winter months are brutal indoor times
– huge mudrooms. kitchen and bathroom right off main entrance and key.
– laundry area with ample drying space. as in basement. (upstairs closets are no good unless you have giant bedroom spaces wasting away)
– more small rooms is better than 1 bigger room, I think
– noise between bedrooms. cellulose in the walls? separate bedrooms by bathroom?
– get real. There is probably a TV and laptops, game machines, tablets, etc. in your future. Where will it/they go? I am not personally a fan of having this stuff in bedrooms away from action. So where does the action go?
– basically the issue is balancing public and private space. And open space vs some small rooms.

Gotta run. Watch this space.

See also:
Here are endless articles on the “move in with parents” theme from recent months/years from the NYTimes

Leave a comment

Filed under contrarian, futuresafe, homesteading, simple, small houses, superinsulation, thinking, zero energy home

Hazy Hot and Humid

HHH today. 88F and humid and it’s only 11:30am. One funny thing about this house is that the basement is currently the DRYEST part of the house. (The temp/humidity sensors I have scattered about are telling me.) This despite also being where we often hang clothes to dry. (We don’t have/need a clothes dryer.) The basement is dry because of a few reasons I assume: 1) basement is very well sealed and insulated, just like the rest of the house. 2) more people upstairs… breathing, taking showers, cooking mac and cheese, etc. 3) we heat our hot water with a heat pump that sucks humidity out of the air (there is a condensate drain) and that’s in the basement.

Anyway, point is… it’s nice not having a dedicated dehumidifier running 24/7 in the basement.

Another interesting piece of info from the temperature sensors is that the HRV is bringing in that fresh 86F air and turning it into 78F air before it sends it out to the house. So we are getting fresh air even in the summer when the house is closed up for AC on HHH days. But that also means that the AC needs to run a tad more with the HRV running. Not that we used much. It’s projected we will use $8 in AC this July. We used $3 last month. And this is with 8 people living in this small house. So not bad.

I think people in more typical houses could achieve nearly the same thing in their basement if they insulate and seal their basements so that they are part of the “inside part” of their house. The walls and the rim joists are easy enough. One problem is the slab and whether there is insulation or poly underneath it keeping moisture out since that seems to be a tricky problem. I think the idea there is to insulate it and have a drainage mat that leads to an interior perimeter drain. Ask someone more clueful than me!

See also:
Marc’s basement retrofit (in 2 parts)
– A good overview of these issues is Deep Energy Retrofit Workshop
Foundation Insulation Retrofits – BuldingScience.com

Leave a comment

Filed under erik-green, passive house, superinsulation, zero energy home