How to live with minimal AC and maximum ventilation
For decades (five to be exact), home design focus has been on sealing homes in order to reduce energy costs of heating and cooling. Such energy efficiency has come at a price of air quality, because unlike, say, water, air cannot be “recycled” over and over without detriment. Carbon dioxide concentrations will increase naturally just from breathing in and out, and toxins build up from emissions from the building itself and the products we use in it. Humidity either builds up from water leaks and water use, or decreases from use of forced air heating.
Is it time to advocate for more “leaky” homes? Well, yes….but controlled leaks are key! The leaks I’m talking about are ventilation with fresh air in a controlled way.
Here at HypoAir we often recommend adding more ventilation from outside to dilute the air in our homes, so it’s constantly on my mind: how do I get more ventilation during the hot months of the year? We tell customers that it’s ok to open windows when the outside air is relatively clear of pollution, but many times it still has dust, pollen and smaller particles, so that presents a problem!
While researching this topic, I found a statement that sums up the problem:
“Every new system installed today should have a Fresh Air Intake. It should not be optional, it should be mandatory. State laws do not force the issues, but health concerns do. Products that we use in our homes have Volatile Organic Compounds (VOCs) that put out gasses as they age. Without a Fresh Air Intake, these VOCs can build up and cause allergic reactions, asthmatic symptoms, and can require treatment with medicine to compensate for the contaminated air. The medical industry does not recognize contaminated air as a medical condition. The reason is, they can’t measure that when you go for treatment. They can only address the problem.
Generally, about 5-10% outside air is desirable. If you don’t have fresh air inside your system, should you add it? The answer is YES, especially if you're doing equipment replacement.” (Texas HVAC company)
Now, which new products aimed at cooling also increase ventilation? I focused on whole home ventilation in a previous post; this one is more geared toward single-room or window units.
The EcoBreeze 2 is a smart window fan that takes outside air, filters it, and delivers it inside as clean, fresh air. It has sensors: if the outdoor air is more hot or humid than indoors, then it shuts down and lets your A/C take over. This is particularly useful in climates where outside ventilation is cool and dry, such as in the northern US. It retails for $229 and has optional MERV 13 filters for replacement (it comes with a MERV 8 filter).
Here’s what to do if you already have a window fan, in order to get cross-ventilation, which is very useful because with only 1 window fan, you’re not really cooling optimally unless you have another window open to allow the hotter air to escape.
- On the hot or unshaded side of your home or room, install any standard window fan that you can seal effectively to your window, but set it to “exhaust” mode (pulling air out of the room).
- On the opposite (shaded) side of the home or room, install Safeguard Window Filters ($51 for the large size accommodates windows from 24-44” wide). In this way, you are pulling cool air into the room through the filters, and exhausting it out through the fan. The filters can be vacuumed several times before replacing the inserts (see achooallergy.com for the replacement filters).
Now, if your outside air is too hot or humid for adding a lot of ventilation, you can still use your window A/C in conjunction with a Safeguard Window Filter. The window filter does not allow a lot of air to pass through (unlike a plain screen, but you can add the ventilation needed and let the AC do the cooling and dehumidification.
If you want to replicate this on the scale of your whole house, many HVAC companies recommend QuietCool Whole House Fans. I grew up with a whole house fan, but this one will not create a rumbling noise, so you can leave it running all night (hence its name). Using Safeguard Window Filters in conjunction with the whole house fan will insure that your home is not filled with bugs, dust and pollen as it pulls in air from outside. What a relief to breathe in fresh air, especially while you sleep!
If any engineers out there are reading this, I’m still looking for:
- a window heat pump unit (heating and cooling capacity)
- with inverter technology (to save energy and provide constant temperature and humidity), and
- a filtered ventilation component, like the EcoBreeze 2, and
- a pollution monitor on the outside to shut off intake at times of high pollution
- Oh–and I like how new over-the-sill designs do not obstruct the window view.
Am I asking too much? I don’t think so–this is 2022–let us know what you come up with!