Ah, air conditioning! We experienced a 110.6% increase in electricity consumption because July/Aug was so darned hot and because, contrary to the norm at our house, we ran the A/C….. apparently we ran it all the time! Although we reveled in the cool, dry air, we paid the bill very grudgingly. Needless to say the A/C has been off for a lot of this current billing period. All that said, it appears that A/C is something to really think about at our house.
The house is a narrow, 5 level townhouse in Center City Philadelphia with a finished floor area of about 4,000sf. That is a lot of house for one compressor that is served by only one return air duct in the very lowest level. Lets think about that. Hot air follows what is called the chimney effect – it goes up and cold air naturally falls down. That means in our house, the hot air that needs to be conditioned goes up and basically gets stuck up there while the nice conditioned cold air keeps getting recirculated through the A/C system….that makes for a very comfy, often too cool, lower level family room but makes for a top level master bedroom suite that struggles to be less hot than outside.
What to do?
One temporary solution we have been trying: Try to force more cold air up by closing ducts everywhere except the upper levels. This was successful in reducing the chill in the lowest level but we still had the trapped hot air to deal with – the experiment wasn’t a total failure but was not a comfy solution.
Another temporary solution: Close the door leading to the top two levels in an attempt to stop the chimney effect, then close off just the lowest level vents and run the system as normal. Surprisingly this worked …to a point. It is still hot up there but not sweltering.
We are investigating two, more permanent solutions for price, energy savings and feasibility. The first is rejiggering the current system to operate as a two zone system: one for the bottom three levels, one for the top two. The idea? Cool the lower levels when needed but focus cooling up so sleeping is easier…and more restful.
The second is to install a totally separate system for the top two floors – allow the first three levels to be conditioned by the main system and install a mini-split system in the space. The idea? Cool up and down when needed.
Either of these would save significantly in energy use. We will let you know how our quest for a healthy, comfortable living environment goes – stay tuned.
