Putting the AC in HVAC

Building a new home in the middle of the summer can be a sweltering experience. There have been days recently where I’ve been installing insulation in hundred degree temperatures, but what keeps me going is the prospect of being finished sooner and getting to relax in sublime indoor comfort.



When it comes to air conditioning, the first thing that comes to mind for a lot of us are the window units that we grew up with. But, there have been a lot of developments in the world of air conditioning since I grew up. Believe it or not, low-cost air conditioners only became widely available about 70 years ago - that’s really one lifetime ago. The next time it gets hot enough to cook an egg on the sidewalk, think about how lucky we are to enjoy such a convenience!

The U.S. Department of Energy has a section on their website about the history of air conditioning. Whether you work in the HVAC industry or you are just interested in how things came to be, it’s definitely worth taking a look at.

Some of the more important breakthroughs in air conditioning technology include the advent of central AC systems — these are standard features in many of today’s new homes, including mine. Another important milestone for air conditioning is the industry’s achievements in making air conditioning more environmentally friendly - most air conditioning systems developed after 1990 do not use ozone eating CFCs and must adhere to minimum efficiency standards.

In designing my eco-friendly home, I am taking my air conditioning system to the next level. I’ve designed the system to pump cool air in through from the top of my house to the bottom - I put the air-to-air exchanger in the attic so that I can maximize the space in the rest of my home. Putting the system components in the attic allows me to eliminate floor grates that get in the way of furniture placement. Also, heat generally rises to the top of structures, so pumping cold air in from the top down will help keep the temperature inside my new home nice and consistent.

There are a lot of particulars when it comes to designing such a system - from placement of duct work to what size mechanical system to purchase, I had to plan every detail ahead of time. I also brought in Ken Eggleston from Mestek’s SpacePak dvision to speak with me about the selections I made - SpacePak is a great product for duct work, and it is my choice for this project.


What do you think about my air conditioning system? Join the conversation and let us know!


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  • Thanks for your comment! You actually read my mind about keeping the mechanical systems inside of the building envelope. I’ve tried several different types of systems over the years, and I think my system will compliment the wall construction system that I chose for this project.
  • As a builder of homes and now an HVAC, Plumbing, Etc. contractor. I still continued my education. I became certified in building analysis and design. As buildings became tighter engineering has changed. The worst place to install any heating/cooling system is outside the building envelope. This is where temperature differences are the greatest with often the least amount of insulation. The leak proof integrity of any hvac system is never 100%. But when ducts, pipes are installed within the building envelope; air, (thermal) leaks are never wasted nor will they create a negative air pressure balance in the building which creates air infiltration elsewhere . Sure it saves space up there, but often at the cost of sizing an additional ton of thermal load. Not to mention increased costs to maintain and service. Today even the venting of attics is being rethought. How much and how this space affects the indoor climate must be considered. High hat lights in the attic plane are frowned on as they leak copious amounts of conditioned air out side unless properly sealed in the attic. This attic area can be too ventilated and subject additional thermal load especially in high winds. My company will not design ducts outside building envelopes. Too often they lead to dissatisfied clients in comfort and cost to operate.
    I still see grand architectural plans that have no thought or consideration to any heat or cool system or even how to design the building to make it all work together. The house construction is also a thermal device that should be considered a vital part of the systems.
    Years ago they got it right. Today they just do it wrong because it is often easier or cheaper or they just don’t care. I have seen so many wrongs that those who believe the majority is right just because they are the majority continue to follow the wrongs. You seem to care a lot and have gotten advice. Seems like a high velocity duct system. I like them when and only when they are installed right. I am actually converting my attic duct system to a ductless system with individual wall hung/ casement units for four upper level rooms. More efficient, better control, individual preferences taken care of, is not affected by door closures, more efficient, responsive to shifting solar loads, no more air balance issues, and easily allow for setbacks when unoccupied without affecting primary areas. From wood / coal stove / fireplace heating to valance cooling, VRF, radiant, solar, Ground source, from steam both private and public, even shivering to stay warm, I have seen a lot. Build what makes you happy, but remember there is always a better way even if it hasn’t been invented yet.