Published on December 10th, 2015 | by Guest Contributor18
How To Really Improve Home Energy Efficiency & Comfort
December 10th, 2015 by Guest Contributor
Originally published on LinkedIn.
By Cameron Taylor, CM
On the eve of Thanksgiving this year, I was grateful I had the good fortune of meeting Nate Adams of Energy Smart Home Performance on his home turf in Cleveland, Ohio. Nate is the real deal; you won’t find many people who care about their work and mission as passionately as Nate does.
Nate took me to a house he has retrofitted this year and is now in the punch list stage. It is estimated to be over 100 years old, survived a nearby natural gas plant explosion back in the 1940s, and is within a stone’s throw of Lake Erie.
This is a house that if you looked at it from the curb it would bring to mind chilly, drafty interiors with steam radiators everywhere to offset the ever-present, creeping chill of winter by a giant lake. Upon my arrival at the house, it was 45ºF outdoors with a 28ºF dew point. Once inside, I was shown via the digital thermostat that the air temperature was 62ºF, and later found the surrounding wall surfaces showed infrared scan readings in the mid 50s.
By any past experience, I should have felt chilly inside that house. Instead, I was asking where I could hang up my coat. The level of comfort was, for lack of a more apt phrase, “womb-like.” I felt enveloped by warmth in spite of the low set point of the thermostat. Why was this? I was intrigued.
Prior to visiting the Cleveland site, Nate had sent me a vast photo library of the house project, from where it started to where he brought it, so a 6’4″ Texan (me), whose building science thinking is largely advised by his predominant cooling climate, felt comfortable in a northern house at 62ºF. Overall, this was achieved by attention to detail pertaining to envelope air sealing and drastic reduction in duct leakage. In addition, Nate bravely specified a 24 KBTUH Carrier Greenspeed heat pump to replace a steam boiler (estimated at 100 KBTUH). A heat pump! In northern Ohio! At two tons!! That should be blasphemous by conventional thought, but it is painfully obvious to me that good building science merged with good HVAC design makes how it is so often otherwise done actually be the blasphemous offender; i.e. piecemeal commodity hit n’ miss mush.
The Greenspeed system approach is where residential HVAC design needs to go as a whole. It involves a mechanical and control strategy where the system’s capacity can infinitely vary between its maximum rated capacity to a turn down minimum much lower than conventional single speed systems can. Single speed (and to an extent, two-stage) systems are essentially binary control; they are either on or off, operating at full capacity or shut down. A system like Greenspeed has an inverter-driven compressor, variable speed blowers and fans, and electronically controlled expansion valves (EXVs) that together can precisely meter refrigerant and airflow for the actual load on the house at a given time of day. For anyone who understands psychrometrics, this is entirely possible from a psychrometric standpoint; now HVAC technology has caught up to make it possible for a well-suited house.
This approach, along with a building envelope that is well sealed and evenly insulated, can deliver incredible comfort at lower thermostat temperature set points. In Nate’s project house, the system is set to run the indoor blower non-stop. Since Nate made sure the ducts were as air tight as possible, and very well insulated, minimal system loss or house pressurization concerns occur with a continually operating blower. The comfort result is minimal air temperature stratification within the home since the air is always in gentle motion, with the system adding or removing heat and humidity as needed. This result will be much less satisfactory if the building shell is leaky and unevenly insulated, and there is considerable duct leakage. Nate knew this going in and worked very hard to ensure those negative factors were minimized.
Part of Nate’s package to his clients is to monitor the results of the retrofit. Too often, high pressure sales tactics over-promise and vastly under-deliver energy savings and comfort gains, because their approach is “silver bullet” based vs. comprehensive. This leaves customers/clients feeling cheated and distrustful of any future person promising comfort and energy savings.
Nate’s project house is essentially net-zero energy ready, meaning if the client chose to add solar panels and battery storage (such as Tesla’s new Powerwall) in the future, the client’s draw from the electric grid would at times go negative to where he could sell power back to the utility, and where electricity drawn from the grid vs. what is sold back essentially equals the same. On a house of this age in a climate with over 6000 heating degree days, this is an impressive feat.
Perhaps what attracts me the most about this house, in addition to its amazing comfort at minimal energy demand, is that it proves this is where we need to focus our attention to reduce dependency on fossil fuels and improve outdoor air quality. So often our media outlets go on at length about what I call “boutique” new house projects, where from the ground up the owner is opting for a super-tight, super-insulated building shell with right-sized HVAC, triple pane windows, etc. That’s nice if you’re building new, but opportunities for our nation’s existing housing stock to be retrofitted to perform like Nate’s project house are boundless, and essential if we are to transform our society from one dependent on geopolitically volatile (think Middle East and terrorism) and environmentally degrading finite fuel sources to a sustainable, renewable base.