Last week I wrote about building a passive solar home twenty-five years ago, and promised some thoughts about "living green" for that long.  So, what's it like to live in a passive solar home?  Here's the big one: In the depth of winter we have an incredibly bright south-facing sunroom, and that's the time of year when human beings need all the sun they can get.  Solar is definitely an attitude improver.  The shortest day of the year - when the sun is lowest on the horizon, and thus highest in that room - is not historically the coldest day of the year, but it's close enough.  In summer, the roof overhang keeps the sun out, even if the trees don't have leaves on them.  In the winter, those leafy trees are bare branches, so they don't block the sun.

Going in and out of the house through the front door is actually through a vestibule closed off from the rest of the house, so gusts of cold air don't penetrate the home so readily in the winter.  It works just as efficiently in the summer, when it blocks hot outdoor air from penetrating the air-conditioned cocoon on those few days a year we feel the need for cool.

I have to say that we did not set ourselves up to suffer on cold (or hot) days.  Our "backup" heating system runs occasionally, especially on days when there is no sun and the outside temperature is below 40^o and we want 68^o indoors.  However, I estimate that we saved somewhere between 25% and 30% on our heating bills over the years, as well as conserving natural gas that we would have burned otherwise.

Recently, as our home approached those awkward years, things have had to be replaced: roof, skylights, doors and windows.  In every case we chose to replace with energy-efficient components.  Most interesting was the replacement of the two nine-foot sliders in the sunroom.  These days low-e is all the rage.  Unfortunately, for our purposes, low-e was not appropriate for a sunroom that had to allow solar energy (solar "gain") into the room.  So, we hunted around for sliders that would allow the highest amount of solar energy into the room.  We ended up with a high-line brand (alas) that included a cellular blind between two of the three panes, and it seems to work very well.  It is also perhaps a bit brighter than it might have been if we had selected something more traditionally low-e.  Since most of the windows in the house are not protected by roof overhangs, we replaced them all with the most energy-efficient, low-e, argon-filled, etc., windows we could find, since we wanted to keep solar gain out in the summer.  They were not so crucial to our comfort as the sliders. 

We have a couple of regrets, but that's not bad for what was "new" technology at that time.

One minor regret is that we didn't opt for the ground-water heatpump (geothermal) heating instead of a traditional gas-fired warm air furnace.  It definitely would have reduced our heating bills significantly (even though increasing electric bills to run the pump), but we decided not to because the system - at least at that time - required almost constant running of a fan because of the huge differential between ground temperature of 55^o and the desirable room temperature of say, 68^o.  Moreover, the air would have seemed cool compared to the ambient temperature.  The additional cost was about $5000 at the time, or about 5% of the total cost of the home.  As it is, our heating and air-conditioning units seem to be holding up well, probably because they don't cycle so much.

Another regret is that we didn't build out roof overhangs on the east and west sides, to protect the interior for the high summer sun.  Even the most efficient glazing can't approach the efficiency of shade.

These are just some random thoughts as my wife and high toast our home on its twenty-fifth birthday.  I would enjoy fielding any questions anyone might have about our experience living green for twenty-five years.  Ask me about Rumford fireplaces.....