Air Date: 4-20-2018|Episode 501
Today on IAQ Radio+ we welcome Nate Adams for Part 2 on the Evolving World of Home Performance. This week we will focus on the HVAC system and how it fits into home comfort. In Part 1 we discussed how what was once called an energy audit is now evolving into something different. The energy programs are changing and the people that perform/ed energy audits are changing how they market their services and what they provide. Some have gone into healthy housing others are pitching home performance and much more comprehensive and costly changes to existing homes. Nate has a unique perspective on the topic and has released the first edition of his book, “The Home Comfort Book” on the topic. We will go into depth on how HVAC systems affect comfort. There may be things that you disagree with but Nate has done the numbers on his project and is confident in his process.
Nate’s company Energy Smart started out as an insulation contractor for existing homes, but has evolved into doing Comprehensive Home Performance retrofits. Their projects are somewhere between a simple attic insulation job and a deep energy retrofit. Nate the House Whisperer is also and author and blogger has an excellent website with case studies about his projects.
Nate Adams is a very smart guy who comes across to our listening audience as likable and logical. RadioJoe and I, both like the way he thinks and his natural ability to simplify complex technical information and making it understandable to the masses. Most IAQradio listeners don’t know that Nate’s father’s occupation is the restoration of valuable classic automobiles. I suppose that’s where his: mechanical aptitude, ability to dissect and solve complex problems, patience, and planning skills come from.
Nuggets mined from today’s episode:
- Quandary over choosing simple or complex. According to Nate, most simple solutions to building performance problems are wrong. He advises slower decision making involving investigation and analysis.
- His 4 tenets of home comfort are: Comfort, Health, Durability, and Efficiency
- Control – Controlling Air, Heat, and Moisture flow is the key to everything. How air, heat, and moisture flows are controlled in, out and within the home. Once the home is tight, the HVAC system deals with this inside.
- Nate’s Five Priorities of Home Performance: Air seal, air seal, air seal, insulate, installing the right HVAC.
- The Blower Door Test is Nate’s divining rod. While utilities may subsidize a blower door test, Nate recommends hiring a professional using the analogy of having someone to both take and interpret the X-Ray.
- Hot coffee mug heat transfer graphic: conduction (touching the cup is through solids), convection (hand over the cup is through liquids), and radiation (handle close to the cup).
- Mean Radiant Temperature (MRT): It’s 5.30 PM on a hot summer day, the sun is beating down onto the home, the attic and walls are hot, the HVAC system isn’t dehumidifying so occupants feel sweaty and uncomfortable. We have 165,000 temperature sensors in our skin, which explains why one part of our body is hot or cold.
- Check out Robert Bean’s (an MRT expert) interview on IAQradio Episode 115.
- Good MRT requires air sealing, insulation and the right HVAC system. How air, heat, and moisture flows are controlled in & out of home and within the home. The HVAC system is running highway miles, washing cool air across surfaces. Living comfortably even in higher temperatures due to lower RH.
Most HVAC systems are too big due to sizing for temperature extremes and redundant waste allowances sacrificing comfort 99% of the time. Once you air seal and insulate, suddenly that new HVAC system you were looking at is very likely to be too large. If you want comfort and control, it will need to be replaced.
- You have a terrible furnace that was sized for where you are not where you are going. The optimum time to improve home performance coincides with HVAC system replacement.
- HVAC system should do 6 things: load matching, filtration, dehumidification, fresh air, right place at right time and humidification.
- With the exception of humidification our cars HVAC system does this, most home do not!
- Good MRT is a tight home with load matching.
- Free quotations and pricing multipliers are the primary causes of poor HVAC system selection. For HVAC contractors estimating is a numbers game, for every 3 estimates made they get 1 job. As such they don’t invest adequate time to right size the equipment, they do math without the right numbers and inevitably specify larger equipment. While better equipment is more costly, it’s not always significantly more costly. Many HVAC contractors triple (3X) the equipment cost to allow for installation and profit. Superior equipment upgrades such as modulating blowers which only cost $200-$300, when marked up 3X become $1,000. It’s worth the added investment if you want better comfort.
- HVAC 102- Sizing HVAC equipment is akin to buying maternity clothes with the off-chance pregnancy will occur. Too prevent callbacks on extreme temperature days, HVAC contractors focus on the extreme days not the meat of the year.
- Most of the temperatures during the year are moderate. The temperature extremes per year only last 90 hours, in spurts of 2-3 hours each.
- Are smaller HVAC systems available? Yes, Carrier’s high-end HVAC system is 1 ton. Mini split units are available in ½ ton. Disadvantage of mini splits include: lack of filtration, don’t provide fresh air, and poor distribution.
- You don’t need a 400 horsepower Corvette in the basement. Most HVACs only have two speeds, all or nothing, (like a Corvette with a gas pedal). Monitors can track this. You want your house to cruise along at 70° F all year without losing speed when climbing hills. Less power with gas pedal.
- No blower door test, insures wrong HVAC, 100% of the time! Most furnaces are 40,000-80,000 BTUs.
- Air leakage is 30%-70% of heating and cooling needs. 1 BTU is the energy contained in one burning match. 12,000 BTUs is the amount of energy needed to melt 1 ton of ice. 80,000 BTU furnaces are very common and cause the most problems.
- Ironically, more efficient ACs stink at dehumidification because they are better at removing heat than humidity. An old school AC might remove 40% latent heat (moisture) and 60% sensible heat (heat in the air). Super efficient models may only be 15/85. If your AC is drastically oversized, or worse, drastically oversized and efficient, it likely does a crappy job with dehumidification.
- Most heat pumps are 24,000, 36,000 or 48,000 BTUs, a small furnace is 60,000 BTUs. High performance homes generally need less than 6,000 BTUs of heating and 24,000 BTUs of cooling. After air sealing and insulation homes need a smaller furnace. Non-modulating furnaces are a bad idea in high performance homes. Heat pump are a better fit in high performance homes.
- Cleveland study shows that 10,000 BTUs is needed 40% of the year between the temperatures of 40°F-80°F and 20,000 BTUs will heat 95% of the time. Smaller or modulating furnaces are needed for better comfort. We can get most 2000 square foot Cleveland homes under 36,000 for heating and 24,000 for cooling.
- Optimum load matching in Cleveland is a 2-Ton 25% modulating.
For more information:
Free chapters and blogs
Buy print or digital copy
YouTube Channel – Nate the House Whisperer
Project case studies & more
Contact Nate Adams
Z-Man signing off
What were silver bullets originally used for?
Believed to be the only way of killing werewolves or other supernatural beings.
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