Benchmarking Solar Window Film Performance in Modern Skyscrapers

Property owners and managers are inundated with potential capital investments during normal times, and in today’s turbulent times, with rising uncertainty and falling budgets, the bar for approving energy-efficient investments has never been higher.  Will the product work?  Will it last?  Will installation be a nightmare?

We hear you, and especially when it comes to potentially investing tens or hundreds of thousands of dollars in window film, a product whose claims are often-misunderstood and sometimes difficult to believe.  Can that little piece of polyester really reduce heat and glare, and improve insulation?   Even when it is not dark and shiny?  The product is made and guaranteed by the 3M Corporation, with claims backed up by the National Fenestration Rating Council (NFRC), but what if you want to see and feel the effects with your own two eyes?

The effect of window film on skyscrapers

Layr installed 3M “Prestige 40”, a high-performance, non-reflective energy efficiency window film to various floors of a class A, single-paned curtainwall building in NYC, and benchmarked the filmed floors with un-filmed floors (>11,000 readings per floor).  This particular building in Midtown east towers above mid-rise neighbors, and is plagued with excessive heat and glare, making the leasing process extremely difficult, and putting excessive strain on the PTAC HVAC system.  We’re happy to share these amazing results with you in graph format; our films consistently decreased peak temperatures by ~25 and ~18 degrees, as verified by electronic temperature loggers.

These films are engineered with nano-ceramic materials, and designed to block harmful ultraviolet and infrared heat, while maximizing visible light.  On larger curtainwalls which can cause temperature and system imbalances, these films are hardly noticeable; here are some pictures from the installation:

For property owners and managers unfamiliar or unimpressed with the benefits of energy-efficiency window film, we proudly share this case study – the proof is in the pudding.

Feel free to call 888-888-8000 , email [email protected], or read on for more details.

Skyscraper problems solved: a case study

Skyscrapers in New York City often use Con Edison electricity for cooling, and steam systems for heating.  Peak electricity cooling costs are often 3-4x the cost of winter heating, and certain tall skyscrapers are plagued by the sun during all four seasons as they do not receive cover from adjacent buildings. While everyone loves a great NYC view, the associated downsides of un-covered curtain or window walls often include:

  • Excessive solar heat
  • Excessive glare, impacting tenant comfort
  • Uncontrollable peak HVAC swings
  • Drafty temperatures during the winter (we will cover insulation and emissivity during a subsequent post)

Whether through installing new windows or window film, solar glass efficiency can be managed using either reflective or absorptive surfaces, which are designed to block varying amounts of ultraviolet, visible and infrared light / heat.  Different buildings and glazing types have different issues, which impact our process and recommendation when it comes to our window film proposals.

This particular client had a number of issues which we considered, including:

  • Excessive heat on the East, South and West elevations
  • Excessive glare, impacting tenant comfort (even though many had solar shades)
  • Uncontrollable HVAC usage and strain
  • The desire for a film that maximized visible light, while not compromising aesthetics
  • Large single-paned curtainwall windows coupled with a lack of adjacent building cover immediately ruled out “very light” UV window films, anything with a 60-70-80% visible light transmission
  • The client’s aesthetic needs ruled out anything excessively dark or reflective
  • The client’s gas / electric / steam configuration enabled Layr to easily leverage its status as a Con Edison Participating Contractor and enable prescriptive rebates

The chosen product, 3M Prestige 40 is a workhorse of a window film.  This modern, non-reflective sun control film works by absorbing solar energy while maximizing visible light.  Relative to the client’s baseline glazing, this window film reduced glare and solar heat by ~55% and ~55%, respectively.  Here are some photos of the before and after:

Results can be felt almost immediately after installation.  To help quantify the benefits, Layr installed temperature loggers at various points on certain floors, to help benchmark the daily peak and average temperature difference, over a three month period.  The results were staggering:

  • Southeast elevation peak temperature (9:45am) reduced by 18 degrees
  • Southwest elevation peak temperature (4:00pm) reduced by 25 degrees
  • Average daily temperature (8-6pm) reduced by 6 and 15 degrees across the Southeast and Southwest elevation
  • Temperature loggers are set to record every 15 minutes, so these data come from nearly 11,000 readings, and were verified by the client “it is much cooler and more comfortable for our tenants”