How three light bulbs help keep my house 72 degrees

How three light bulbs help keep my house 72 degrees 

By Doug Mcdonald, NYPH Member

It has been cold in January up here in New England. A cold snap moved into the northeastern US, and through it all the interior temperature was maintained at 72 degrees without any active heating – with the notable exception of my tiniest of supplemental heaters, items one doesn’t think typically of as heaters at all.   In the past three years I have learned to apply Yankee ingenuity to my Passive House.  I’ll try to explain.

Even in a Passive House, one always needs supplemental heat sources for when the weather turns abnormally cold.  The weather has turned recently, with the morning temperature averaging about eight degrees.

The first winter living in this super-insulated retrofit house, we weren’t yet done insulating the cellar or installing all the ventilation systems when frigid temperatures came.     The house,  walls, floors and foundations are an unbroken concrete structure, wrapped in 10″ of insulation, yet planted firmly in the ground.   And my building’s concrete core started to slowly shift, getting cooler and cooler.  This temperature shift was an annoyance  for me because one of the things about a Passive House is that the floors shouldn’t feel cold – they should be at room temperature.

After this bothersome experience, we made substantial progress in adding cellar insulation, and installing the cellar ventilation.  And while the insulation and ventilation were essential in completing the work, given the retrofit nature of the work, I worried.  I wanted something simple to counter act any lingering tendency the cold may have to creep into my floors.

Sitting there I also took note of the three light bulbs in the cellar crawl space and I realized that, (1) heat comes from the bulbs, (2) heat rises, and (3) that the bulbs are attached to concrete pillars which are spaced evenly around the areas that get cool. That was an a-ha moment.

So in this past cold snap with temperatures only in the single digits for days, I went down into my basement, contorted myself through the crawl space and journeyed deep into area and turned on all three lights.  After a few days of continued cold, I was pleased to realize that not only was the cold held at bay, but the three bulbs seem to have been giving off just enough heat to maintain room temperature floors in that coldest of weather – if perhaps giving off light that no one needs – and feeling very good on my toes.

This would never work in a house that was not built to, or retro-fitted to, the Passive House standards. I’m personally amazed and grateful that three CFL bulbs in a crawl space can actually be a supplemental heat source for this yankee family.

But the question is for my next client, (who is a very very tall skinny rock and roll star) do I use the same Yankee logic? Will they venture into the crawl space to turn on the light bulbs?  Let me know your thoughts.

Doug Mcdonald