Got old windows? Check out this Low-E Window Film from EnergyLogic Film.

This revolutionary new film can add upwards of 90% more insulation to your current set-up, equivalent to making a single-pane into a double-pane, a double-pane into a triple-pane, etc…

Why Windows?

In commercial buildings, replacing an old, underperforming window is not high on the priority list, usually as a result of some back of the napkin payback estimate that doesn’t take into account occupant performance or thermal comfort. Even though, often times, the downside of old windows is more than just lost heat. Think about where you’re sitting right now- is it drafty? Hot? Cold? Just right? Every time this sensation passes through your body, it distracts your mind. Not a problem if you’re surfing the internet reading this article, but if you’re in the middle of some intense mental work, it can be a game changer.

How much of a game changer? It’s tough to say. Some studies report that a temperature change from 65 degrees F to 75 degrees F in an office setting can reduce employee performance by as much as 40%. That equates to reduced employee performance (lost work) of roughly 4% per Fahrenheit degree change in an office setting.

The actual temperature affect on employee performance figure may be higher or lower based on a multitude of non-linear variables which are impossible to define for “all” scenarios such as space and employee characteristics. Space characteristics being location of employee to window, overall amount, size, and positioning of fenestration, window aspect, window coverings, use of window coverings, etc. Employee characteristics being clothing type, gender, metabolism rate, age, time of year, type of work being performed, tolerance for heat change, and so on.

But it does illustrate the point that employees do not perform optimally under variable temperatures. Aspects such as space and employee characteristics make defining an exact employee performance number with temperature somewhat impossible, but we can use a rough estimate to scrape out ballpark costs…

What are the costs of under performing windows?

It depends largely on how much a typical employee costs you, how much the windows are affecting temperature in your space, and how much your utility bill is for the year.

For example, let’s say you have a small space in Downtown Denver with five employees, each getting two weeks a year of vacation, working normal business hours (40 hrs. per week) and each making $40,000 per year, the utility bill in the space is $350 per month.

The employee costs equates to roughly 2,000 hours per work for $40,0000 over the year, or $800 per week, $160 per day, $20 per hour, or $0.33 per minute.

Based on the 4% loss in productivity per degree, there are several options from here. On the conservative side, let’s say the total loss in productivity due to drafts and temperature changes is 5%, for the complete range of temperature changes.

Daily, in this example, 5% of lost work equates to only $8. But per year, this equate to $2,000. Multiply that by five employees, and a modest employee performance loss of 5% per day equates to $10,000.

Comparatively, the rudimentary energy savings number from the efficiency gain would probably not be more than 10-20%. Based on this example utility bill, this would equate to $420-$840 per year.

On on aggregate yearly basis, under these assumptions, the total loss attributed to the leaking windows could be approximately $10,840 per year, of which less than 8% is from utility bill.

Another way would be to assume that per day, your old windows are distracting them for a total of 5 minutes (conservative estimate), and your monthly utility bill (gas and electric) is still $350. Let’s do some math to see how much that employee costs per minute:

$40,000 / 50 (weeks) = $800 per week

$800 / 40 (hours) = $20 per hour

$20 / 60 (minutes) = $0.33 per minute

At $0.33 per minute, times 5 minutes a day (lost work), that single employee is costing you $1.65 per day, or $8.25 per week, or $412.50 per year for zero work.

In this case, there are 5 employees, so all of them together cost over $2,000 ($2,060) a year, with 5 minutes gone a day.

Assuming the additional heating/cooling costs take 15% of your annual utility bill, ($630/yr in this case), the total affect of your old windows is about $2,700 ($2,690) per year.

Most of the time, the window guy won’t do any nifty employee performance calculations, but this should give you a reasonable framework to quantify simple affects that employee performance can have on cash flow, if you wish to include this in your decision. Just ask yourself, what would Google do? I can almost guarantee you that given the option they would do the math that includes employee performance.

Back to the cool new window film: What makes this product so appealing in the retrofit or energy efficiency marketplace, is that the payback period for replacing old windows for brand new windows is typically in the 10 to 25 years+ timeframe. Remanufacturing is not an option for most buildings, and adding a thermal blind may help, but it won’t be a cost justifier. For most owners, the business case for new windows is just not there.

Though costs vary for this application, and payback period will largely depend on many factors, the company is touting payback periods within 2.75 years. This means that for most users, a more realistic timeframe is 3-5 years. A lot will depend on how bad your current set up is (in terms of insulation, or emissivity) and how much glass your space has. However, all in all, this is a true game changer in the window world.

What does “low-e” mean?

To a non-engineer, “low”= small amount, and  “e” refers to emissivity, or how much heat (radiant) passes through the window. All together now: “low-e” = “high heat reflectance”.  A high amount of heat reflectance means the window is more insulated,and it will keep what you want in and what you don’t want out: In the summer, it keeps hot air out, and in the winter it keeps hot air in. Good things for a building.

Thanks for reading.