Are Triple Pane Windows Worth It?

Why I chose triple pane for my 9-unit apartment building in Vermont (climate zone 6).

Hey. Welcome to the next edition of Small-Scale Sunday from Brick + Mortar where small-scale developers get one actionable tip on acquisition, financing, design, construction, or operations.

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I just spent $60,000 on 38 windows for 501 Main.

Well, $55,243.25 to be exact.

At 5% of our budget, that’s one of the largest line items for the project. And, with 15-week lead times plus a hard no returns policy, it took a few months of research, shopping around, and coordination to get right.

There are a mind-boggling number of variables when it comes to windows—trim, color, style, tempered, fire-rated…

But the choice between triple or double pane gets a lot of attention. And it’s a key decision where the cost/benefit is often misunderstood.

Here is my rationale for choosing triple pane.

Ok, so first—I went with Kohltech. They’re known for high quality, energy efficient vinyl windows. And they’re sold through a local distributor that I’ve come to trust (shoutout to Chad at Loewen Windows in WRJ).

The triple pane option on Kohltech casements gets an 11% premium over the base price with double pane—a $4k add-on for the entire window order.

Next, the benefits. Two pros here:

Benefit #1: Ongoing Cost Savings

Warning: this requires putting on your math hat for a sec.

I’ll try to be brief.

Window efficiency is measured in U-value, or BTU / [h * SF * °F] for the other engineers out there.

U-value is a measure of heat loss. The higher the number, the lower the performance of the window.

Kohltech casement triple pane windows have a U-value of 0.15. Double panes are 0.25.

To compare overall building performance with triple vs double pane, we need to calculate the U-value of the entire building.

U_building = [ 7% * U_window ] + [ 60% * U_wall ] + [ 17% * U_roof ] + [ 18% * U_foundation ]

The percentages represent the relative square footage of each component (i.e. 7% of our building is covered by windows).

Then, we input U-values for each of the components (I won’t get into those calculations here but comment below if you’re interested).

U_building (using triple pane) = 0.038

U_building (using double pane) = 0.045

The result?

Triple pane windows reduce heat loss across the entire building by 19%.

At 501 Main, each unit will have its own ½-ton Mitsubishi heat pump for heat and AC. These are highly efficient with a projected $1,000 in heat/AC costs per year per unit.

That’s almost $200 in annual savings per unit. And with resident-paid utilities, this is money that goes back into residents’ pockets.

So, no, that savings doesn’t directly hit my bottom line. But, the long-term play here is to increase resident retention by reducing their overall costs of living.

Benefit #2: Comfort Levels

Comfort is hard to quantify. But it’s still an important factor.

Poorly insulated windows create cold drafts in the winter, especially in northern climates like Vermont.

501 Main’s studio apartments are small (450 SF), so it’s critical to maximize every square foot. Cold drafts around the oversized windows will make the apartment feel inhospitable. This, in turn, may spur resident complaints and lower retention.

Also, double pane windows can allow condensation to build up on the interiors. Over time, this could lead to water damage if severe enough. Maintenance issues are the secret killer of good real estate investments and we want to do what we can upfront to minimize them.

Summary

At 501 Main, triple pane were the way to go:

1. Only 11% increase in cost, or $4k

2. 19% energy savings on heat/AC

3. Added comfort levels in small apartments

But, keep in mind—the math will be different for each project depending on window manufacturer, building layout, and mechanical design.

Just make sure you dive into the numbers.

And, in case you want to see what a window quote looks like, here is 501 Main’s.

Until next week,

— Jonah

P.S. Want to connect? Find me on LinkedIn and my projects on Instagram.