Note: This is the third article of a three-part series covering green building plastics (1) trends, (2) material/process advances and (3) applications.
In the U.S., the demand for green building materials — products that contribute to LEED credits — is expanding 13 percent annually and is currently generating sales of more than $70 billion per year. Key trends having a strong influence on the worldwide building industry are:
- Energy codes will keep raising the bar, and enforcement is catching up
- Mandatory disclosure rules will incentivize building owners to invest in energy efficiency
- The pace of building certification will increase
- Building energy management systems are in growing demand
- The connection between efficient buildings and the smart grid will continue to grow
Let's start by taking a look at nanotech optical window films. Nanotechnology is being applied to multilayer optical films — made of polyester, acrylic and polyethylene naphthalate — to develop a new generation of light management.
Nonmetal nanomultilayer sun control window films can be composed of approximately 240 nanolayers, yet be thinner than a Post-it note. They also allow more visible light to enter windows than traditional window films. These films are transparent, not dark or mirror shiny, blocking ultraviolet (UV) damage and the heat, not the view.
The absence of metal prevents corrosion on the film, a serious issue in humid areas. They also provide certain safety and security by holding glass together during destructive weather or vandalism. These films also do not interfere with cellphone reception.
3M's Prestige Series window film based on multilayer nanotechnology:
- Allows 40-70 percent of natural light
- Rejects up to 97 percent of solar infrared light
- Reduces by up to 60 percent the amount of heat coming through the window
- Rejects p to 99.9 percent of UV rays that fade/damage furniture
3M has also commercialized a line of Ceramic film based on nanotechnology that distributes ceramic particle material so fine that it is invisible to the naked eye. This spectrally selective film rejects up to 80 percent of the sun's IR light to reduce energy costs and also blocks more than 99 percent of UV light.
Elsewhere, Hüper Optik's proprietary Nano-Ceramic films use nanoceramics chosen for spectrally selective properties that maximize total heat rejection. The neutral toned films are 100 percent dye-free and 100 percent metal-free and offer a comfortable visible light transmission (VLT) ranging from 5-70 percent without appearing shiny because of their low visible light reflectance.
Next, let's cover insulation wallpaper. Adding wall insulation to an existing home can be a difficult project. Insulating outer walls can range from adding insulating siding to filling empty wall cavities with blown-in insulation, to major remodeling involving gutting walls to add insulation.
Climapor insulating wallpaper, produced by German insulation manufacturer Saarpor, provides a way to add wall insulation with greater ease by adding insulation to the interior of existing houses.
The wallpaper — which saves heating costs, improves indoor climate and can serve as wallpaper primer — makes use of Neopor, graphite enhanced expanded polystyrene (EPS). Neopor from BASF is EPS that contains graphite particles that reflect thermal radiation to reduce heat losses.
The insulation wallpaper is 4 millimeters (mm) thick and meets class 032 thermal conductivity requirements and European fire class E. The product resists temperatures up to 75 degrees C (167 degrees F).
It is glued in place with commercially available Styropor adhesive and can also serve to cover wall cracks and surface irregularities. At 4 mm thick, Climapor wallpaper has the same insulating effect as a wall made from 85 mm of solid brick, 98 mm of sandy limestone or 262 mm of standard concrete.
Finally, let's delve into SPD (suspended particle devices) light-control film, made of a polyethylene terephthalate (PET) film material and a polycinyl butyral-like (PVB) interlayer. SPD light-control technology, developed by Research Frontiers Inc. (RFI), is protected by more than 500 patents and patent applications. RFI has licensed 33 companies worldwide to use SPD film technology in a broad range of applications.
SPD, also referred to as light valves, allows instant and precise control — either manually or automatically — in the shading of glass or plastic in a range of products. SPD emulsions combine special polymers, particles and other chemicals that can be coated into a high-performance light-control film used in windows as well as many other products.
SPD application technology is defined as follows:
- A thin film laminate of light-absorbing microscopic rod-like particles dispersed within an emulsion/liquid suspension
- The film is enclosed between two glass or plastic plates coated with transparent conductive material
- The particles, randomly oriented due to Brownian motion, block light from passing through the film — although SPD can go quite dark (as either tints of blue, gray or black), it doesn't provide privacy.
- When electrical voltage is applied, the particles align so that light can pass through.
- By regulating the voltage, either manually or by a sensing device like a photocell or thermostat, users control the amount of light, glare and heat coming through products such as windows and sunroofs.
- The greater the voltage, the more aligned the particles are and, therefore, the larger the amount of light that is transmitted. It is infinitely adjustable from a light transmission range of less than 1 percent to as clear as about 70 percent, and can be regulated anywhere in between.
Research Frontiers
SPD laminate structure (left) and smart retrofits of architectural skylights (right).
For example, the test case homeowner on the right (during the afternoon) figure example shown above reported a 22 percent reduction in zoned cooling bills during July and August by applying SPD-Smart retrofits to three existing kitchen skylights.
SPD technology product applications include: SPD-Smart windows, sunshades, skylights and other architectural applications; automotive windows, sunroofs, sunvisors and mirrors; aircraft and marine windows; instantly adjustable variable-tint eyewear; and flat panel displays for electronic products.
SPD light-control technology can be used on flat or curved glass or plastic surfaces, and is the world's only light-control technology to combine fast switching speed, optical clarity over a wide range of light transmission, and uniform switching over large surface areas (i.e. no iris effect).
A small but constant electric current is required to key SPD smart windows in a transparent state, and 15 large SPD smart windows can be operated for less than the energy required to operate a simple night light.
