I love looking at roofs.  Whether I’m driving down the road or riding on elevated subway trains, I’m looking at roofs.  Even when gazing from my window, I like looking down at my neighbors’ roofs, searching for signs of heat loss.  It may seem a little nutty, but it’s fun for me.  I’m a private investigator eavesdropping on energy bandits who are preying on unsuspecting houses.  Today it snowed and as I looked down at the roofs of the brownstones below my window, I noticed several violations and pulled out my notepad.

Conditions were perfect.  The temperature was just under 30 degrees and it had been snowing for an hour or two.  Wherever the temperature of the roof was colder than 32, the snow would stick.  It would melt wherever the heat from the inside of the house escaped to the outside.  The lack of snow is an indication of where there is inadequate insulation or a failure in what we in the PI business call the building envelope.  That may not excite some, but private investigating is my life, and I’m ok with that!

Take a look at this photo of a row of brownstones.  The first house on the left has been vacant for quite some time.  They probably have the heat on at 50 degrees to keep the pipes from freezing and still the snow is melting as it lands.  I hope when it is sold, the new tenants think about this and give it proper insulation during their renovation, because right now I’m guessing there is none.

The second house to the right is just such a case.  The contractor is almost done with this gut renovation.  The owners have no doubt spent millions of dollars on it, yet all the snow is melting on the roof.  This indicates that an energy efficiency specialist was not hired since the roof is the most important area to insulate.

A closer look reveals snow melting in a circle on their deck.  Very strange.  I’m guessing there must be a drain under the pavers going through the house, thereby conducting heat from the inside of the house to the deck.  Notice how the snow is melted next to the wall too, suggesting that heat is escaping through the walls. The parapet on the left is also devoid of snow.  My hunch is that they used fiberglass insulation inside the exterior walls.  Fiberglass, (the least effective insulation on the market) does not block air flow and allows warm air to rise through the wall cavity, heating up the parapet.

The third house is better insulated but they are losing heat through thermal bridging.  If you look closely you can see the lines of melted snow in a grid pattern.  That shows where the studs are.  The contractors installed insulation as the code requires, but unfortunately heat also travels through the studs – in between the insulation.
The fourth house is where I would put my energy bill.  Any heat they are producing is staying inside where it belongs, keeping the occupants warm.  Then the sixth and seventh houses are going back to the old ways of throwing heat, energy and money, to the wind.

When these structures were built, energy was cheap and plentiful. Now we need modern solutions for modern problems.  It is common to see tradesmen specializing in plumbing, tile, carpentry etc.  Today, it makes sense for architects to augment the team with an energy efficiency specialist to provide a thorough, impenetrable building envelope.