Creating an Energy Efficient Old House

Polar Coaster Winter Ahead (photo: Farmers' Almanac)

With Labor Day behind us, it's time to start thinking about cooler temperatures, because in Maine, winter will be here soon.  And with the Farmer's Almanac promising a 'Polar Coaster'  and a 'wild ride' this winter, we will be testing all the energy efficiency work we did on our mid-century modern house.  This house was built before the oil embargo of the 1970's, so energy efficiency wasn't a priority!  It needed lots of updates.

Energy Audit - looking for issues during blower door test

How do you even start improving the efficiency of an old house?  Well there are some big ticket items you can do, but some simple DIY improvements can make a big improvement too.  And we started with an energy audit, that helped us identify areas to improve.  The audit showed us that we had a lot of air leaks, thanks to a blower door test that identified lots of areas to make improvements.

What did we do?  Well let's start with the big ticket items.  The biggest bang for your buck in insulating an old house, is to improve the insulation in the roof.  Since half of the house was 'stick built', meaning it used conventional lumber and framing practices, we focused on that roof first.  With our low slung, contemporary roof, we don't have a conventional attic.  So we drilled holes in all the different rafter bays and filled them with dense pack cellulose.  With our 2x12 construction, that gives us an R value of 42.

Dense pack cellulose is blown in through holes in a fabric membrane, to keep it in place

PLUS, we added a layer of foam insulation board over top of that, with a new rubber membrane roof above it.  That brings total roof insulation to 60.  That's a HUGE change from the crumpled R-19 insulation that we found when we opened up the ceilings.  

Foam insulation getting lifted up to roof

We also installed a high efficiency propane boiler, which runs at 95% efficiency!  The old boiler ran on oil and was original to the house.  It was held together with silicone and bailing wire, so it was time for an update.

We also replaced every single window, door and skylight with new, energy efficient versions.

The new 8x8' skylight replaced single pane glass that was siliconed to the roof rafters

And while the new units are important to improve efficiency, it's just as important to create a tight seal around every single window/door/skylightof, in our case with low expanding foam insulation (the stuff you buy in a can) to get an incredibly robust seal.  Why low expanding?  Because you don't want the foam to expand so much that it warps your door or window.

But even with these changes, we are still seeing high heating bills.  So we had our insulators come back and install foam insulation in the sills around the basement ceilings.  This might seem like a low payback project, but we immediately saw a 10% reduction in our heating bills!!  That's a big change for such a little job.  And it probably helped that we also installed foam insulation board on the basement walls.

Foam insulation applied to the sills in the basement ceiling made a huge difference in our heating bills

And since we were buying new appliances anyway, we made sure they were all Energy Star compliant.

But we also did a lot of simple DIY changes.  We switched to all LED lightbulbs, which use a minimal amount of electricity. And I went around the entire house with my infrared camera (available to attach to your cell phone and very easy to use) and a caulk gun and caulked every single little air pathway I could find.

Blue is cold..... see how there was a draft coming up from the floor?

Foam board against the slab foundation

We were also advised by our energy auditor to dig a trench around our slab foundation and insert foam insulation board.  He said this provides a thermal barrier between the concrete and the cold ground and was one of the biggest improvement actions we could take.  We obviously couldn't do this in a Maine winter, but finished this up over the summer and are anxious to see how much of a difference it makes.  

But of course the proof is in the pudding.  As you might remember, we did a Blower Door Test when we first started the project.  This essentially creates a giant vacuum in your house, so you can see how much air infiltration you have.  

I was VERY excited to see the improvement.  So excited, that Justin told me not to get my hopes up.  He typically only sees a 10% improvement in an old house of this size.  So as he hooked up the giant fan in the doorway, I waited with baited breath.

30% IMPROVEMENT!!!  Woo hoo!!

And guess what???  We saw a 30% improvement!!!  He was amazed, I was thrilled and we are hoping that will translate into some sweet heating bills this winter.  And it's important to note that while expensive things like new windows and doors help, it's the simple work of sealing up every possible crevice, to ensure no air is getting through that can make a huge difference.

Finally, we are working with our energy auditor to get credits back from Efficiency Maine.  In our state, which has some of the oldest housing stock in the country, there are lots of rebates to help you made your place more efficient.  So we will be getting a nice rebate check for some of the work we did.  

So come on Polar Coaster - we're ready for you!!!

January 2019

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