A house is not just home; it is a system of heating, cooling, air flow and air pressure. Every time a door is opened, air is exchanged. When someone walks down a hall or enters a room, air flows around and with their body. When a heating, ventilation and air conditioning (HVAC) system is in use there is a constant exchange of air throughout the home. As air flows, it can be pushed or sucked into crevices and gaps. Some of those gaps may be between the floor and a closed door, or even small crevices between an attic hatch and its frame. There are straightforward solutions for these areas, but what about HVAC ducts?
HVAC typically includes a central unit with a principal duct projecting out, including branches flowing off to different areas of the home. Installers will generally use specialized materials for sealing up the joints and branch off point to prevent little air leaks. Most of the time the tapes they use do the job quite nicely, and that would be the end the subject. However, the job of a furnace and ducting is to project warm or cool air to the vents. Where the vents empty into is the target destination for the air flow, not the inner walls, ceilings and floors in which the ducting travels. Therefore ambient temperature changes caused by HVAC ducting leaks or temperature transfer from the ducts themselves are a waste of energy.
Let's take a look at a project where a 60 year old home previously heated with oil is being changed over to natural gas, and thus requires a new furnace to be installed. More than likely that would include updating at least some of the ducts, which probably run through areas insulated with mineral wool (if at all). The home will already be leaking air like a sieve, simply through outdated building practices. Any use of spray foam insulation will benefit the building, especially in attic and crawlspace areas. Bathrooms and kitchens in homes of this era usually experience problems with humidity, which of course means mold is ready to form if it hasn't already. Air flow is important in homes with dampness, but in a controlled manner. The homeowner needs to be able to manipulate the temperature and force of flow in order to maintain control over energy costs. No more pumping heat into a room filled with holes.
The perfect fix for this older home would begin with a careful assessment of its overall efficiency, air leaks, and the homeowners heating and cooling needs. Using closed cell spray foam insulation, all crevices, voids in walls and floors, holes, soffit gaps and so on, are quickly repaired. Then, using spray foam insulation once again, apply a layer of foam to ducting wherever possible making sure to include points of transition and joining. Assuming the windows have been upgraded to double pane thermals, the home is now a highly efficient and airtight building. Ventilation is controlled by the homeowner for maximum energy efficiency, plus the chance of mold caused by excess condensation is removed.
As stated above, a house is a system of air flow. Therefore designing a new home for maximum efficiency should include a system-wide approach to HVAC design. In the older home project above, there is only so much updating one can achieve without gutting every room. With a new building, one can start from scratch and use all the right techniques and methods for energy efficiency throughout the whole home. In doing so, each component is utilised to its full potential. Every ounce of value is attained from the home, giving the homeowner a far superior product that will certainly have excellent resale value.
It is up to the professionals to know how and when to apply these approaches, plus gain the training to do so properly. Contractors should already be striving for maximum value for the end user, especially in the area of building with green materials and energy efficiency. It may cost a little more at the outset, but the savings in the end are highly beneficial. The first step is in proper training. Staff members designing and installing HVAC systems along with spray foam are better prepared to carry out an excellent job when they receive appropriate training. If your firm chooses to hire a spray foam insulation company to install the foam, it would still be prudent to supply your staff with training. The more knowledge they have, the more likely they can spot issues and solve them before they cause larger problems. It is worth saying again: invest in training and it will pay dividends when it comes to those tricky jobs where on the spot problem solving and critical thinking skills are essential.
There is a lot of chatter in the construction industry about building codes and their apparent inadequacy. The now famous Mike Holmes has made it his mission to teach the general public all about the damaging effects of using just minimum code, bad contractors etc. While his approach may be a tad on the side of overkill, he has a point. There is a mass transition happening in North America home building. Architects and engineers are moving towards tight building construction and hugely reduced heat flows. Builders, in turn are forced to change their perspective on home building. The way things were done in the past is gone. Now the home is a system, not just a series of boxes.