airtight homes

In cold climates, airtight homes are the best solution for comfort, healthy air and energy savings; and also for smaller heating and cooling equipment... You should bet on it.

However, since highly sealed home interferes with ventilation and the heating and cooling system size, some cares should be taken when adopting such a strategy in an existing home (see Sealing and Ventilation, below).

Airtight Homes & Air quality
Air leaks may help to dilute indoor carbon dioxide or chemicals like formaldehyde from building materials. But instead of being a source of fresh air, air infiltration is often a source of problems like moisture and dusty air. And since the penetrations and the cavities of foundations, crawlspaces or basements associated to air leaks can be contaminated with chemicals, radon, etc., that's often the inverse of fresh and healthy air. Airtight homes can provide much better air quality through mechanical ventilation.

Getting high levels of air sealing

To get an airtight home you should install as much insulation as possible in your attic and exterior walls and all over the home's envelope: foundations, floors under crawl spaces and slabs...

If possible bet on new wall insulation technologies for new homes (Structural Insulated Panels and Insulated Concrete Forms).

Anyway, you need more than high levels of insulation. You also need high levels of air sealing.

Air leakage should be solved by using proper sealing products (caulks, sealant foams, weather stripping materials) for small gaps, and air barriers for larger surfaces (in wood and steel frame homes) . See: Air Sealing vs. Insulation

airtight homes & Ventilation

Indoor air quality requires a certain amount of fresh air, and there are technical specifications setting the amount of it.

But since air leaks are largely driven by the weather - and particularly by the wind - they aren't the best way of getting that fresh air. Air leaks easily provide too much fresh air in cold and windy weather (when it isn't welcome) and too little during hot and mild weather conditions...

Never expect to get good fresh air through air leaks. You can get it through natural ventilation, in many climates or in some periods. But you can’t have it via air leakage. An airtight home - with a mechanical ventilation (HVAV) system - is the best approach and the only way to get healthy fresh air in harsh cold climates.

The airtight home approach & climate

There are some few cases in hot climates where the airtight home approach can be advantageous, namely in situations involving mechanical air conditioning in parts of the house. In hot climates, air conditioners only make sense in highly airtight rooms (that's the only way of reducing the energy bills).

But that can't be the rule. Cooling strategies in hot climates should involve other broader strategies. Mechanical air conditioning is a solution with a limited scope in hot climates. See: Air Conditioners & Hot Climates.

In moderate climates, the airtight home approach may also be of little use or not really relevant. It's a strategy to consider, but all depends on weather patterns and heating and cooling strategies. It's in colder climates that the airtight home approach is truly relevant and important.

Mechanical ventilation systems & air thigh homes

In cold climates, where homes can’t be naturally ventilated during most of the year, mechanical ventilation (a Heat Recovery Ventilation System (HRV) or an Energy Recovery Ventilator system (ERV)) is the best ventilation solution, and the only way to get healthy indoor air in airtight homes.

A high-quality exhaust fan in each bathroom and kitchen, ducted to outdoors, is important but insufficient in such climates.

Airtight homes and Heating and Cooling Systems

The ultimate goal of an airtight home strategy is to get much smaller heating and cooling systems or to eliminate central HAVC systems (by using zone cooling and zone heating based on gas stoves, for instance...).

Many of these strategies involve passive solar heating and cooling strategies, that is, a careful planning of the shape of the house and its windows, the orientation to the sun, etc.

In older homes - without proper ventilation, depending on cracks and leaks to let in air, where CO2 and other pollutants from combustion appliances and other sources may add up creating an unhealthy air in the home - the airtight home approach is difficult to carry out and demands technical and professional assessment and solutions.