To start with, as the home gets tighter for energy efficiency, the concerns for the products within the home and the proper (and controlled) ventilation become greater. Green homes utilize products that do not introduce unhealthy amounts of off-gassing from products. Materials such as paints and finishes, plywood, and carpet can give off Volatile Organic Compounds (VOC) and urea-formaldehydes. Ironically, those same chemicals that give a home the desired “new home smell” are the ones that can make us sick. Specifying low VOC paints, finishes, and carpets and low or no urea-formaldehyde glues in plywood will promote a healthier indoor environment. Additionally, the products the occupants bring into a home can have the same impact. Labels such as Green Guard and GreenSeal can assure the designer, builder, and occupant that unhealthy substances are not being introduced into a home.
Coupled with that, maintaining the proper ventilation is paramount to a healthy home. Building science has illustrated the need for a tighter building along with the disastrous impact that moisture can have on the building and occupant alike. The old saying “a building needs to breath” while describing how older buildings maintain a healthy indoor environment is not an accurate statement of what we want from a building today. Controlled mechanical ventilation that balances both incoming clean supply-air with the stale outgoing air is the desired outcome. Numerous products exist from balancing bath fans to whole integrated systems like Heat and Energy Recovery Ventilation systems (HRV and ERV), which provide proper ventilation while reducing energy and moisture movement. These holistic systems are very effective and do not introduce substantial costs. Additionally they can be integrated into heating and cooling systems (HVAC) in a cost efficient manner.
While the benefits of photo-voltaic roof panels for electrical generation from the sun and geothermal HVAC units to capture the benefits of the ambient ground temperature can be seen as green, their benefits become even greater when coupled with a well designed and built building. Products such as rigid board insulation placed on the exterior of a home can reduce the thermal transfer through conduction and reduce air movement at the same time it controls the moisture movement in the assembly. Fiberglass insulation, commonly used for decades, is being used in conjunction with, or totally replaced by, foams that are spray applied. These products more effectively manage the thermal energy transfer within the building assembly cavities. There are some advanced products such as Insulated Concrete Forms (ICF), pre-cast foundation systems, and Structurally Insulated Panels (SIP), which provide the structure, thermal boundaries, air control and moisture control with only one or two construction steps.
Once the energy conserving building has been designed and specified, it is critical that the HVAC system be designed in accordance with the building. Old rules of thumb for sizing should not be used and can result in higher, unnecessary energy costs and potentially less healthy indoor environment. New “engineered” systems will be smaller and designed to run with greater efficiency. Some new popular equipment will actually measure the outdoor temperature and adjust both the heating source and its delivery to the need by measuring and comparing outdoor temperatures and requested indoor temperatures. There are also thermostats that will read the occupant behavior and adjust temperatures up and down automatically.
Once the building envelope products and HVAC systems have been aligned, the products that are more costly and associated with “green” systems – such as PV and Geothermal – will have an even greater impact. PV panels use the sun’s energy to produce energy and have the potential to bring energy costs to zero when coupled with a building and HVAC system that conserve, then produce, energy effectively. Geothermal HVAC units can create the heating and cooling comfort by transferring the ambient temperature from the ground to the home. These units have the capability of producing more energy than the energy they consume.
Another category of green products are those that use less of our natural resources. This group is made of renewable materials, re-cycled materials, and materials that simply use less natural resources while not sacrificing the performance of that product. Some products that are made from renewable resources are panels made from highly compressed straw, bamboo flooring and lumber that has been certified to be harvested via specific and sustainable methods. Recycled materials are finding their way into countertops, carpeting and flooring to name a few. Flooring that is laminated and has a finish of veneer lumber is an example of how materials can be combined to use less of a precious natural resource (the final finish veneer) but functions the same as the more traditional solid flooring. Plumbing products are used that limit flow to conserve water. These products have been re-engineered from earlier versions so the limited water flow is not noticeable as the water pressure increases.
Construction waste management, although not a “product”, is another method that reduces the strain on natural resources. Green projects have a specific waste management policy and may go into separate dumpsters or segregated at the processing facility for recycling. Some other aspects of a waste management plan are the use of specific material cut lists and utilizing dimensions that fit common sizes of materials while not yielding excessive waste.
Products will continue to evolve. They are the most rapidly evolving aspects of a green home. PV systems will continue to evolve to become less noticeable and more efficient in their production of electricity. Water heating systems are becoming more efficient as they capture the sun’s energy or use efficient heat pump technology. And more and more products are combining recycled products. In fact, as more products make the claim of being “green”, the Federal Trade Commission (FTC) has stepped-in to provide guidance for green claims. Any product that makes a green claim needs to state with specificity what makes it green to avoid the “greenwashing” that leads to confusion and misunderstanding.