Thriving On Low Carbon

Two years with a minisplit heat pump

With the exception of one week in February 2011 where I switched back to the oil boiler to take some data before it went away, the Fujitsu 12RLS has now been heating the house for two years. The meter reads 2,584 kWh. So, about $250/year to heat House 5, in mostly milder-than-normal weather. This is about 1/4 the cost of operating the oil heating system.

Most houses in the northeast have a boiler and forced hot water heating, and most of the rest have a forced air furnace -  both are central heat systems. Without some energy retrofit work, most houses can't be converted over to a single zone minisplit and have adequate heat throughout the house. In cases where the central heating system is due for replacement, a multizone minisplit may be worth considering. We've done just that at SMC, for a client with a 30 year old boiler and a poorly designed distribution system. That system cost over $20K installed, though.

A single zone minisplit costs about $4K installed. In cases where the entire house doesn't need to be fully heated, or houses in which a point source heater can carry the load of the house in mild winter weather, a minisplit can be a great retrofit. In the Pacific Northwest a major study has been conducted using a single zone minisplit as a retrofit to the many electrically homes there (http://www.bpa.gov/energy/n/emerging_technology/DHP.cfm). On average they have shown a 40% reduction in heating energy, with some homeowners experiencing much higher savings (the ones most likely that kept the doors to the bedrooms open!) The electric resistance heat is still in place, to be used as needed. It's very possible to consider a similar approach in fossil fuel heated homes. The best candidates are houses with open plans, so the heat pump can heat a good portion of the kitchen/dining/living space, and houses where the other rooms are located where natural convection (warm air rising) can transport heat to them. It would be best for the existing heating system to be one that has more than one zone, so that the zone(s) not well heated by the heat pump can still be heated by the existing system.

Best suited might be houses where a number of the rooms are not occupied - the large house with a single occupant, who needs a bedroom, bath, and the public areas heated, not the other four bedrooms and two baths. In essence, it's going back to the days when a central hearth kept the public spaces warm and the peripheral spaces were much cooler.

These changes will likely be driven by fuel prices, so they are more appropriate where there isn't natural gas - houses where oil, propane, and electric resistance are the primary heating fuels. As of the 2009 EIA energy use surveys, there were almost 9 million households in the northeast (New England and mid-Atlantic states) using those fuels as the main heating source. That's a significant opportunity.

 

MA Construction Supervisor License

Not long ago I got a bee in my bonnet about getting my Construction Supervisor's license in MA. Working as I now do for a company that is quite diverse, but is fundamentally still a design/build company, it feels right to join a number of my colleagues, mostly but not entirely our foremen, in holding a construction supervisor's license.

It was an interesting process. You have to show at least three years experience, and take a test. The three hour multiple choice test has 75 questions and is open book with these books: The 2009 IRC, 2009 IECC, 2009 IBC; MA amendments to these; the MA Architectural Access Code, and the OSHA regs governing construction. Obviously a test like this doesn't really test one's ability to supervise construction - it's really testing how well you can quickly find stuff in the code books. Most of this is more suited to those in the design professions than the construction profession. Nonetheless, it plays to my strength as a standardized test-taker, so I can't complain. When I began prepping for the test I was a bit cynical about the process, but was surprised to leave the test center with a very positive feeling about the process. It forced me to look at aspects of the code and regulatory environment that I wasn't really aware of, which was good.

MA is implementing a requirement for continuing education units for a CSL, so I actually will have to do something in the next couple of years to retain the license. Hopefully that will also feel worthwhile.

Window shades

One of the technologies I have tried in House 5 is insulating window shades with side tracks. I got four Ecosmart cellular shades from Gordon Clements at Gordon's Window Decor. One is translucent, and the other three are blackout shades, achieving that by using aluminum foil inside the cells. Because the foil is reflective to radiant heat transfer, these shades have a higher insulating value than the translucent version. They also have two rows of cells, to further increase insulating value. In cross section they look like this:

The side edges of the shades are slit and a plastic fin that is installed on the sides of the window opening runs in the slit and makes a rudimentary and simple seal. The bottom has a weatherstrip to seal to the window sill. Here's a close-up of the shade and side fin:

Here's a shade fully down:

And here it is with the top partially down, nice for daylight with some privacy:

 

So how do they work? Well, they definitely insulate - when opened in the morning a little puff of cold air drops out. And there is condensation on the glass, notably more than the unsealed, single row cellular shades we have elsewhere in the house. My colleague and friend Andy Shapiro did some careful measuring on one of his and calculates that the effective added R value is about R-4.

These shades aren't cheap, although they are a lot less money than a window replacement. If you have leaky windows, these won't solve that problem - they're not that air tight. A storm window will do a better job of sealing, but won't add as much insulating value. I think that if you are considering shades at all for privacy reasons, and have reasonably tight windows, an insulating shade such as these can make sense, and they handle fairly large windows well. We've noticed that the largest one, covering a triple window about 7 feet wide and 5 feet tall, is perhaps a bit too large for the hardware that rolls it up - we help it up with one hand as we retract it in the morning.

Putting the two shades in the living room down definitely makes that room more comfortable to be in, as the two largest windows in the house are on the east and south of that space, and it's where we spend a lot of time. The change in the radiant temperature is noticeable. So all in all we consider this to be a success as we've applied it here.

Greed Ate Winter

Jill and I went out to Santa Fe for a Zen Buddhist retreat called Rohatsu, which celebrates the Buddha's enlightenment and is Dec. 1-8 every year. It was quite warm this year, and I could be outdoors in a tee shirt in the afternoon sun. My teacher, Roshi Joan Halifax gave a Dharma talk in which she noted how Rohatsu in Santa Fe used to be really cold and snowy (I recall her leading us in walking meditation outdoors in the snow). As she touched on climate change, her pithy assessment of the change in the weather was "greed ate winter".

A foundational aspect of Buddhist teaching is that suffering comes from greed, hatred, and delusion, hence the reference - our collective greed leads to excess consumption, and therefore emissions, and therefore climate change.