Question: In Summer, will keeping the garage door up or down conserve energy?

Great question!  Many factors come into play with this....

If your garage is insulated, closing the door will help conserve energy, particularly if there is a bedroom located above the garage.  However, if the garage is not insulated and is facing South, the heat gain can be intense! Therefore, leaving the door open will allow for air flow through it, resulting in potentially lower ambient temperatures. 

 Another thing to consider is if you have a refrigerator or an HVAC system located in the garage. Refrigerators can overheat during the summer (specifically the motor and electronics), so allowing for air flow is always a good idea.  And don't forget to clean those coils! If the HVAC system is located in the garage, sealing and insulating the duct work must be done to reduce the communication with the main body of the home. Think of it this way: any holes in your duct work allow the unconditioned air of the garage gets sucked into the duct system and sent throughout your house. Insulating the duct work will make sure the warm or cool conditioned air will stay that way until it gets inside your home.

Remember to air seal all holes, gaps and openings that could potentially create pathways to the home! This could include garage door hardware, electrical, plumbing and duct penetrations. Another good idea is to make sure there is solid weather-stripping on any entry doors to the home.

Stay cool!