The emphasis placed upon upgrading energy efficiency within existing residential properties in recent years has caused some homes to suffer from insufficient ventilation and poor air quality. A balance between indoor air quality, retrofit costs and energy conservation is required to ensure healthy living conditions remain in older homes being upgraded to today’s building codes and standards.
Yesterday’s Construction
In the typical Canadian or Northeastern U.S. home that was built in the period before the popularization of the R-2000 concept (1960-1980), insulation and ventilation standards were of secondary consideration to construction costs, due to the availability of inexpensive energy (heating/cooling costs). Insulation values comparable to our R-20 were not uncommon and still considered adequate for the climate’s seasonal fluctuations. Window technology was often still reliant upon “storm” window use in the winter to supplement the high heat loss potential of wood frame windows and single glazing. As a boy in Ontario, I was continually told by my parents to “go outside and get some fresh air”. The reality is, due to construction and material standards at the time, I was getting as much fresh air inside then as some children get outside now. The amount of ‘accidental ventilation” that occurred in homes of the time and type through drafts caused by ill-fitting or poorly sealed windows and doors was significant and beneficial.
Todays Energy Upgrade Emphasis
In today’s energy upgrading market, supplementing attic insulation, upgrading forced air furnaces and replacing old technology windows with modern low energy loss types is the rule of the land in older homes. Home owners may be at worst unwitting risking their health creating poor indoor air quality conditions or at best, merely transferring the destination of their heating dollar in the process. By upgrading windows and doors, eliminating drafts and sealing their home to reduce heating and cooling energy expense, home owners are eliminating a large portion of the “accidental ventilation” that aided indoor air quality and mitigated the effects of mould within the home. I continually encounter customers who discount the potential dangers of poor indoor air quality and mould based upon their experiences with homes prior to the R-2000 concept. Mould is a common and naturally occurring organism now as it was 40-50 years ago, today however, we live in homes effectively sealed to the outside that rely upon mechanical ventilation instead of accidental ventilation to reduce the concentration of contaminants and saturation of the indoor air environment. Increased humidity levels within the home cause condensation at the thermal break, making the addition of a Heat Recovery Ventilator (HRV) a requirement for all energy upgraded homes to avoid mould.
No Free Lunch
In the home heating and cooling battle, nothing is without compromise or cost: there are no free lunches. Home owners need to balance the following real world costs, with the anticipated energy savings:
Old Technology
Costs= Regular maintenance costs + heating/cooling energy costs.
New “Upgraded” Technology:
Costs= Replacement widows and doors + replacement or supplemental attic insulation + purchase, install and energy cost associated with a Heat Recovery Ventilator (HRV) + heating/cooling energy costs.
Given a long enough pay-back period and service life of the upgraded components, there can be a case made for breaking even on the investment in your home’s energy efficiency but it depends upon the size of the home, the costs of the upgrades required, the climate and long-term cost of heating/cooling energy. If your home requires $15,000 in windows, $2,000 in insulation and $2,500 for a Heat Recovery Ventilator, how much does your energy consumption need to drop, and over how many years in order for you to recoup your $19,500 investment? Factoring in the cost of electricity for the HRV to function all day/everyday, if a home owner could save $100 on their monthly heating/cooling energy costs, they would be fortunate. At that rate, the pay back period for the upgrade costs required to save the $100 per month, it would take 16.25 years to break even on the $19,500 investment in your home, if no new windows or HRV’s were required within that period.
The Air Quality and Energy Efficiency Balance
What is the solution for the home owner who needs lower heating and cooling energy costs, healthy indoor air quality and financial responsibility? The balance that I have struck in my own home, is applicable to all those home owners in the Northeast United States and Eastern Canada:
1. Upgrade attic insulation to R-50 and upgrade the attic ventilation to better than basic building code in your area to avoid attic mould.
2. Replace existing windows only as they fail and are required to prevent water intrusion. If a compromise has to be made for aesthetic reasons, replace curbside windows first.
3. Monitor indoor humidity levels to ensure they do not reach the mould danger zone of 60% or higher in non-summer months. Mould growth will occur on readily supportive organic materials caused by airborne humidity in homes with non-summer seasonal humidity above 60% for greater than 24-48 hours. Mould growth supported by humidity often occurs first in areas near outside walls at ceiling level of homes, based upon warm (in this case warm and moist) air rising. Only invest in the purchase and running of an HRV when humidity control is required to control mould growth.
4. Manage your heating and cooling costs through use of programmable thermostats, turning your heat down and your A/C up. Consider the use of passive cooling methods such as blinds, awnings and reflective window films.
Remember, the contractor that wants to save you money by having you purchase new windows, doors, insulation, furnaces and Heat Recovery Ventilators are not doing it as a public service, they are doing it to make money. Strike a balance between estimated savings over the long-term, the investment required in the short- term, and the potential health risk associated with poor indoor air quality caused by insufficient natural ventilation.