While greater interest in different home ventilation options may be new, ventilation itself is not. For as long as humans have lived, worked, cooked and created in indoor spaces–ventilation solutions have been necessary. Ensuring good home ventilation is an easy step to improve indoor air quality as a whole. Keep reading for a short history on home ventilation, how changes in the way we build homes makes ventilation even more essential and what the many benefits of good ventilation are.
Why is Ventilation Necessary?
In simple terms, ventilation is purely the exchange of new and old air. Therefore, ventilating a space quite literally is the process of removing stale air and replacing it with fresh air. For us humans, that process is breathing, and we understand it’s essential. Ventilation is equally essential for your home.
How exactly does ventilation improve your home’s air quality? Regular air exchange and good air circulation keeps indoor pollutant levels down. Indoor pollutants can be anything from dust mites to pet dander to radon and all are hazardous to both health and home. Proper ventilation also prevents moisture build-up which helps prevent against mold damage and mildew growth.
The bottom line: we ventilate our indoor spaces to create healthier, cleaner indoor living environments.
The History of Home Ventilation
Home ventilation has evolved over time alongside ever-changing building standards, energy goals and daily life activities. Our modern understanding of the importance of ventilation is still developing, but the need for ventilation has always existed. In fact, the Romans are credited with developing early heating and ventilation systems in the third century BC. Since humans first used open fires to heat living spaces, society has in turn needed methods to ventilate said spaces.
Before the 20th Century
One of the first official laws regarding ventilation was created in 1631 by England’s King Charles I. It was decided that bad indoor air caused by home heating methods were creating health problems. The result: all homes and living spaces in England had to have 10-foot ceilings at a minimum and windows had to be higher than their width to improve natural ventilation indoors.
The first ventilation per occupant measurement was recommended in the late 19th century. American physician J. Billings argued for higher ventilation rates and suggested 30 cfm per person as a minimum and 60 cfm per person as the goal. These recommendations were adopted by the American Society of Ventilation Engineers (ASHVE).
Massachusetts was the first state to make 30 cfm per occupant a law in 1914. Twenty-two states soon followed suit and created ventilation laws and standards of their own. ASHVE became the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), and the organization published a code of minimum ventilation requirements for the first time in the 1920s.
Despite the focus on ventilation, it was not seen as a prevalent concern. At the time, homes were not well insulated and air circulation between indoors and outdoors occurred due to leaks and cracks. Because there were minimal construction codes advising for airtight houses, spaces had a natural built-in ventilation method.
Compared to early recommendations, ventilation standards have actually decreased. Today, the ventilation recommendation is that homes “receive 0.35 air changes per hour but not less than 15 cfm per person.” Recent studies on ventilation and health effects, however, suggest higher ventilation rates are needed. For now, though, 15 cfm is considered the minimum for good home ventilation. And that number is already difficult for a majority of homes across America to achieve.
So, what has changed in the way we design and build homes that makes good ventilation hard to maintain? Most modern homes today:
- Are well insulated – making it easier to maintain comfortable temperatures indoors, however at a cost to indoor air quality and ventilation.
- Are built with energy-efficiency in mind – Older homes have a reputation for being drafty. Outdoor air finds its way inside thanks to cracks, leaks and openings in a house’s foundation and around windows and doors. This made HVAC systems less effective and more costly. Hence, the shift to today’s goals of energy-efficient homes that make the most of the HVAC system.
- Include air-conditioning – which was not a given before the 1950s. It was only in the mid-century, after World War II, that air-conditioning became the norm and homes were expected to include A/C.
- Have a goal of being “airtight” – in order to keep both cool air-conditioned air and warm heated air indoors for longer periods of time. Rather than relying on open windows in the summer and burning wood in the winter, we rely on our HVAC systems for temperature control and comfort. The best bang for the buck? Tighter homes with less leaks to capitalize A/C and heat costs.
For these reasons, modern homes lack natural ventilation. And despite the many benefits of tighter, more energy-efficient homes, these changes had a significant negative impact on home ventilation. The consequence: airtight builds mean stale air, hazardous indoor pollutants and odors all remain inside and in our breathing air longer.
Mechanical Ventilation is Necessary for Good Indoor Air Quality
So, what’s the solution for better home ventilation across the board? Mechanical ventilation. Mechanical ventilation systems are a helpful indoor air quality upgrade that ensures the home or indoor space has fresh air at all times. The advantage of a whole-home mechanical ventilator is that it installs directly into the home’s HVAC system. This means it uses the ductwork, registers, grilles and air filters already installed in the home. It’s simply an addition.
A home ventilation system improves air circulation, air exchange and air quality. There are exhaust-only, supply-only and balanced home ventilation systems options available. We recommend opting for balanced ventilation systemsbecause they combine the best of both worlds (the exhaust and supply processes.) There are two types of balanced mechanical ventilation systems to choose from, ERVs and HRVs. Both work by using fans and ductwork to pull fresh outdoor air in and push stale indoor air out. The best option for your home will depend on location, climate and what other air quality problems your space struggles with.
Mechanical ventilation is the solution for airtight homes and for spaces with leaky uncontrolled air. But how do mechanical ventilators differ for older homes compared to new homes?
Older builds are inherently leaky. They benefit from a certain level of natural ventilation that helps circulate indoor air. However, uncontrolled air leakage and exchange is not a good enough ventilation method. The added natural ventilation found in older homes simply means the space meets the ventilation standard (and that isn’t saying much.)
You also should consider that the air source is not ideal. Many drafty areas originate from a basement or crawlspace, usually suffering from poor air quality. Harmful pollutants like radon and other soil gases in addition to mold, mildew, VOCs and formaldehyde are likely entering the home alongside the air flowing in from these areas.
Plus, in addition to all of these problems, most leaky homes actually require air-sealing. And once an older home is re-insulated and renovated, it faces the same problems a newer construction would.
For newer construction, mechanical ventilation is practically a given. In fact, it’s actually considered best practice among home builders to create an airtight home and improve ventilation after the fact. This is because in the long run, it’s still healthier for occupants and more cost-effective to build airtight homes. It just means homeowners should choose home ventilation upgrades to counteract the negative energy-efficiency effects. Or as recent ASHRAE standards suggest, build tight and ventilate right.
Choosing Home Ventilation Upgrades
The best home ventilation option is one that allows for greater control over your home’s air. And controlled air is only possible with the addition of a mechanical ventilation system. Whether you live in an older build, a new construction or a home that falls somewhere in between–all likely suffer from poor ventilation for some reason! Every house would greatly benefit from a mechanical ventilation system with improved indoor air quality. We can put you in touch with a local IAQ expert in your area who can help determine the best home ventilation system for your space!