How can I more effectively cool my house by managing windows with outdoor temperature changes?

Question

How can I more effectively cool cooling my house by managing windows with outdoor temperature changes?

My current strategy

I open all my windows when the temperature inside the house is warmer than what the temperature is outside (I use the temperature from Accu-weather). I do the reverse when the temperature is warmer outside.

My Environment

I live in northern Canada (Edmonton, Alberta) and during the mid-summer the temperature gets quite high (room+15C) between the hours of 1 to 9 PM. During the rest of the time it is generally lower than room temperature (room-5C).

Issues I have found that confuse me

• I am not always available to open/close the windows when the temperature changes (I am away from 8AM to 7PM). So effectively I am missing lots of potential house cooling time because I close my windows in advance anticipating the day's high.
• When I check the thermostat it says its hotter inside than it feels outside some times (without any wind).
• When it is windy but warm, would it be better for me to open my windows anyway or would this be counter productive in the long term. From what I could find on this, hot wind is better then not but if it is not, direct wind I assume would heat up my house even more.
• One side of my house is always in the shade, even when it is very hot outside this window always feels cooler, I wonder if I should just leave it open anyway?

Answer 1

Unless you can secure windows so no-one can enter the house don't compromise your safety by having windows open while no-one is at home. Open windows of a vacant house make it easier for burglars to enter the premises: either to ransack or vandalise the premises while you're not at home or they can wait for you so they can take your wallet and/or your car keys, or demand/do other things.

When it comes to heat, two things affect comfort – temperature and humidity. High temperature with high humidity is very uncomfortable. There is also a radiative aspect to heat. Items that have been heated, like the walls and furniture, will radiate the heat stored in them when the air in the room cools. Because of this, cooling of a house is improved by having continuously flowing, flow through ventilation.

When it's hot and windy close all windows, otherwise the inside of the house and its contents will heat up more quickly and maintain that heat.

Given the considerable amount of time you're not a home during the day a computerised system which would open and close certain windows depending on temperature differences between inside and outside the house would be ideal.

Leaving the window open on the shady side of the house would be OK, except on very hot days.

Other options for temperature control are:

• roller shutters on the windows
• insulating drapes
• plant deciduous plants around the house that would provide shade during summer
• reduce heat reflected onto the house by other buildings or large expanses of concrete paving, or similar

Answer 2

Fan forced ventilation systems

Given the description of your situation, it may be worth investing in a controlled ventilation system. In New Zealand, these are popular where the air intake (and a good filter) is in the ceiling space, where warmer air can be drawn into the house, however the controller of such systems can generally be set to target a particular temperature and the system will adjust the fan speed based on whether it can improve the temperature or not.

Ducting can be used in the ceiling space to distribute the air to different parts of the house. Obviously this requires a ceiling space to be able to be installed; not every house has that.

In your case, since you have more of an issue with too much heat, you could draw air from outside at the shady side of the house. It would work even more effectively if you could add some evaporative cooling, especially if your climate is dry when it's hot.

Answer 3

An interesting old book I found recently entitled "Everywoman's Home Encyclopedia" had an article about keeping homes cool in summer. Here are their basic recommendations:

• Whitewash roof to reflect heat.
• Use "sun blinds" or thick curtains on doors and windows.
• Open all windows at night to cool the house as much as possible (except ground floor windows if this would be a security risk). Close all windows as soon as it starts to warm up in the day.
• Place arrangements of leafy, cool looking plants around the house to help it feel like a cool, shady garden.

I particularly liked the last suggestion, as making your house look cooler can help you feel more relaxed.