Penjerex Window Insulation film Frequently Asked Questions

The information below is intended to provide potential residential and commercial Penjerex customers with a general understanding of our insulating window film product.


Please contact one of our agents for specific information and to arrange a presentation at your home or business premises.

About Penjerex

What is Penjerex insulation film?

Penjerex window insulating film is developed and manufactured in Japan by Nitto Denko corporation which is a global leader in technologically advance films and tapes.


Penjerex is a high clarity thermal insulating window film which is a very good alternative to retrofit double glazing.  It can provide better than 95% of the effectiveness of conventional retrofit (4/A6/4) double glazing units for around half the cost.


It reduces rate of internal heat loss by 44% in cold months and also reduces excessive solar heat in hot summer months by up to 25% over clear glass, which provides an ideal outcome for the New Zealand climate.  It also provides additional features including 99% UV radiation reduction and vastly improved safety against shattering glass panes.


Technically, Penjerex is a new technology ‘low emissivity’ window film that provides the same benefit as new low-e glass but can applied directly to existing window panes.

How does Penjerex increase the thermal insulation of my windows

The new technology ‘low emissivity’ characteristics of Penjerex reduces heat loss by reflecting internal infrared energy (heat energy) back into the room which reduces internal heat loss by 44% when compared to standard 4mm clear glass panes.


In hot weather it reflects heat energy from the sun by approximately 25% while also reducing the UV radiation by 99%

How does Penjerex compare to other brands?

Penjerex insulating window film is manufactured by Nitto Denko, a market leader in insulating window film.  It has the leading ISO tested performance data for internal heat loss reduction, visual clarity and has had its performance figures accepted by the International Glazing Database (IGDB) which is supported by the US Govt Department of Energy.


There are very few low emissivity window films available and this new technology shouldn’t be mistaken for older style ‘solar cut’ window films. Penjerex is a new type of technology.

How is Penjerex installed

Penjerex is installed to the inside surface of a glass window which doesn’t require any external scaffolding and isn’t dependent on having a sunny day to complete the installation.


This is the basic process:

  1. Clean the inside surface of the window and frame edges with a very fine scraper surface (Penjerex is always applied on the inside)
  2. Spray the Penjerex and the window with the detergent/water mixture for mounting the film
  3. Apply and trim the film to match the shape of the window pane.
  4. Remove excess water solution with a squeegee to activate the adhesive on windows.
  5. Installer tidys window frames and all surfaces.


Windows of an average size house can be installed in less than a day.

Does Penjerex have a warranty?

Yes.  The standard Penjerex replacement product warranty is for 10 years for residential and commercial installations.  Commercial warranties offer a 1 time transferal to a new building owner.  An approved edge sealant may be applied to the installed window film in certain instances to ensure warranty is valid.


Nitto Denko underwrites the warranty which includes removal and replacement of film that, in an unlikely event, should experience; adhesive failure, bubbling, crazing, cracking, delamination, excessive and unusual discolouration, peeling or other manufacturer’s defect.

How can I view a sample?

The best way to view a sample is contact a Penjerex agent and arrange a demonstration of the Penjerex window film and its ability to reduce heat loss and excessive solar heat gain in your home or commercial building.


Our agents are trained to explain important features and properties of the film with a heat lamp demonstration kit.

Can Penjerex be used in commercial buildings

Yes certainly.  Commercial building HVAC units consume around half of the electricity used in an office building with approximately 50/50 split between heating and cooling energy depending on the building design.


The NABERS programme is now being promoted in New Zealand to improve commercial building energy efficiency and Penjerex is a cost effective product to assist commercial buildings lower space heating and cooling energy while improving occupant comfort with virtually no impact on daylighting.

Can I install the film on double pane windows?

Yes.  Penjerex can be safely installed on double pane (thermally insulated) windows to further improve insulating performance while adding UV and solar heat reduction properties that double glaze units don’t necessarily have.


Our Agents offer guidance where Penjerex is appropriate and in what circumstances any particular risks may be relevant.  The manufacturer warranty of some double glazing units may be void when Penjerex is applied.

When should I not get Penjerex installed

We recommend all homes have good ceiling insulation installed as this will reduce heat loss and assist to reduce moisture problems that can cause condensation.


When looking to ‘close the thermal envelope’ the next logical step is to insulate windows as these can contribute 25% to 48% of heat loss according to BRANZ estimates.


There are several options with retrofit window insulation and we believe Penjerex is the most cost effective and easy to install product available.

Does Penjerex block out sound like double glazing?

Penjerex doesn’t reduce external sounds by any noticeable amount.  If reducing outside noise is a concern for you we recommend looking for other products that address this problem.

After Installation

Is Penjerex removable?

We don’t have any expectation that you would ever want to remove Penjerex from your windows but if the case arises then yes, it can be removed.  It is applied to a glass surface with a pressure sensitive adhesive that cures over the course of about a month.  Even when the adhesive is cured the film can be removed with a razor fine scraper causing no damage to window surfaces.

Will Penjerex stop condensation on my Windows?

Penjerex isn’t marketed or sold with any expectation to reduce condensation on window surfaces.  If you do have a condensation problem in your home, there are other products and solutions available that can assist to lower the impact of this.


When Penjerex is applied to a window surface it does reduce the size of condensation droplets creating the appearance of a fine mist instead of the normal large droplets running down the window.


Condensation tests result in 5 times less condensation volume forming on Penjerex windows when compared with standard single pane glass.  Reducing the volume of condensation reduces mold and damage to wooden window frames.


Please read the Condensation customer guide available on our website for more information.

Is Penjerex scratch resistant?

Penjerex is manufactured with a superior hard coat surface which is scratch resistant to normal wear and tear.  Our product care information gives you all the advice to keep your insulating film in great condition.  It also informs you of what not to do with your Penjerex windows.

How do I clean the Penjerex surface after installation

Common neutral detergent solutions (that do not contain chlorine, acid or ammonia) may be used to clean Penjerex, along with a damp soft cotton rag or microfiber cloth.  Avoid any abrasive cleansers, paper or towels.  We suggest using the same water & baby shampoo mixture used to install the film (one teaspoon of neutral shampoo to a litre of water).

Will Penjerex stop my furnishings from fading?

Penjerex does an excellent job of dramatically reducing fading of furnishing, art and wall and floor coverings.


Major causes of fading are a combination of ultraviolet (UV) light, visible light, and solar heat.  To prolong the life and preserve the appearance of your furnishings all of these factors are reduced by application of Penjerex on your windows.

Will Penjerex distort my view when I look out the window?

Penjerex has the highest visual light transmission rating of any low emissivity or solar cut window films and is virtually indistinguishable from a clear window pane.


It is ideal for character homes as it does not impact on the aesthetic of windows and frames and has minimal visual change when viewed from the outside of your home or a commercial building.  This allows Penjerex to be applied to specific ‘problem’ window areas or individual building floors without impacting the exterior look.

I often see purple bubbling window film on cars. Will Penjerex do this?

Penjerex is a new technology high clarity window film that doesn’t use the dyes associated with the older style car and office buildings which change colour and can create an unsightly rainbow effect.


Penjerex is virtually clear and comes with a replacement warranty for 10 years.

I've seen DIY window film. Can I install window film myself?

Penjerex installers are certified to Nitto Denko standards for quality purposes.  It takes a substantial amount of experience to be proficient in applying Penjerex so we only allow our trained agents to install for their customers.