Allison Bailes (Energy Vanguard)

Ever since buying a house I've been engrossed in this topic along with indoor air-quality and mechanical HVAC systems. There's so much to know about these topics and I feel it helps when dealing with HVAC companies to make sure I'm getting what I want and not be price-gouged. One expert I follow on these topics is Allison Bailes, he has a blog entry on a similar topic of duct design[0]. I find his way of breaking down certain topics simple to follow and enjoy seeing how he's implemented his teachings in his own home. [0] https://www.energyvanguard.com/blog/basic-principles-duct-design/

> everything that reduces the need for HVAC This is the answer! Even more important than insulation is air sealing, so you keep the conditioned air inside. I've learned an enormous amount about building efficiency from https://www.greenbuildingadvisor.com/ and https://www.energyvanguard.com/

Matt's videos are worth watching, but it's important to note most his videos are motivated by his sponsorships and it's often hard to parse out when he's shilling and when he's not. Betters resources with real science can be found at * https://www.energyvanguard.com/blog/ * https://www.greenbuildingadvisor.com/

> Maybe give people free HVAC upgrades to filter more particles. HVAC and indoor air quality (IAQ) is a fascinating topic and it takes good design to get it right. In most HVAC systems you can't just stick a higher MERV filter in and expect good results because they are designed for specific amounts of air flow. Thicker filters cause more air resistance which reduces air flow and fan efficiency which means less comfort and greater energy use. Often a better strategy in a retrofit is to increase air sealing (a good energy recommendation anyway) and install an E/HRV to exchange indoor for outdoor air with a good filter in it. PM2.5 comes from outside so this should take care of it. https://www.energyvanguard.com/blog/unintended-consequences-high-merv-… https://www.energyvanguard.com/blog/7-reasons-your-filter-isnt-improvi…

R-Values. Exponential going the wrong direction. After R-15 or so you slip into the long tail. Good article here- http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/76941… PH is performance based, but the religion is a bit excessive on R. I do greatly value the air tightness and the quantitative approach. High R-Value walls are tough to build and get expensive quick. Double wall, exterior sheathing, more parts, more fasteners, etc. We use SIPS walls/roof that have very good R, very little thermal bridging and outstanding air tightness while being fast to build.

> Also just a guess: is the story with heating that your heat pump is sized based on your max heating load, and so losing up to 25% of its capacity on the coldest days means it would never be able to catch up? The unit I have has a HSPF2 rating of 10.5. It's very efficient at the transfer of the heat available. Heat pumps can extract more energy than the consume. New heat pumps can operate over 300% efficiency. The best furnaces are generally in the mid-90 percentages. I have a dual-fuel system and can set where the heat pump locks out. The system is rated to a COP of 1.75 at 5F. Meaning it's still over 100% efficient at that temperature. The unit will operate down to -22F but would be at, likely, less than 50% capacity of output. To save on wear and tear of the unit, however I have my setpoint lockout at 15. It would have to be significantly below 0 for days on end to have a problem. But even then the furnace would be providing primary heat. There are people in my area that heat their entire home with ductless heat pumps [0]. My unit is rated at 48k BTU. The furnace at 100k BTU. I only really "need" the furnace for emergency. But we do have sub-zero highs rather often and during those days the heat pump would be running continuously. I also have an 80 gallon hybrid heat pump water heater which has saved us thousands over the last few years. 98% of the year it only uses the heat pump. [0] https://www.energyvanguard.com/blog/can-a-heat-pump-work-in-minnesota/

There are multiple articles readily found about complications of using positive pressure: https://www.medscape.com/viewarticle/581344_7 http://www.mdedge.com/ecardiologynews/dsm/5224/hospital-medicine/compl… https://www.ncbi.nlm.nih.gov/pubmed/2199002 To my mind, this is actually related: https://www.energyvanguard.com/blog/54084/Why-I-m-Not-a-Fan-of-Positiv… One of the problems you run into with any lung related mechanical devices is the need for proper sterilization. From what I gather, this is much less of an issue with negative pressure ventilation. People in iron lungs are people with fundamentally compromised immune systems. Exposing them to germs forced into their lungs by positive pressure while potentially damaging their lung tissues in the process strikes me as a great way to give them a deadly infection, sooner or later.

It depends on your goals. One saying is that "a good window is still a poor wall". A quality double glazed window still has about 10x the heatloss of a well built wall. Here's a summary with a link to more: http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/55519… Shades can help with privacy, but what if you want the privacy at the same time you want to be capturing heat? And if requires active control --- well, that's by definition not passive. Interestingly, the new movement in high efficiency houses is frequently for low solar gain windows: well insulated windows with special coatings to admit less heat while still admitting light. From another standpoint, gigantic expanses of windows are rarely the best way to build a pleasant room. As well as being a rare crossover between Computer Science and Building Architecture, Christopher Alexander's "A Pattern Language" has lots to say on this. Some excerpts here: http://kk.org/cooltools/a-pattern-language/ Which is to say that opaque heat-gathering walls serve a purpose that is separate than that served by windows. Both have their place, and they don't tend to replace each other directly.

He talks about transport and heating That doesn't leave much left when you look at the energy flow once you remove domestic, commercial and transportation usage and replace it with electricity. A tiny amount left for plane s(and reducing per flight as planes get more efficent and battery planes start coming to market), and industrial gas usage. https://www.energyvanguard.com/attachment/llnl-us-energy-flows-sankey-…

> Metal buildings don’t breathe. Humidity condenses on the metal, turns into mould, then you have real problems. Neither do modern homes made out of timber and wood sheathing. This is a good thing. Humans need to breathe, not buildings. Buildings need to be able to dry: * https://www.energyvanguard.com/book-house-needs-breathe-or-does-it/ * https://www.energyvanguard.com/blog/myth-a-house-needs-to-breathe/ * https://www.greenbuildingadvisor.com/article/buildings-dont-need-to-br… * https://www.youtube.com/watch?v=CIcrXut_EFA

DIY forum, https://ecorenovator.org/forum/ HVAC blog, https://www.energyvanguard.com/blog/ HVAC pro forum, https://hvac-talk.com/vbb/ Heating forum, https://forum.heatinghelp.com/

Because in the winter the thermal energy within your room will “flow” out of those “cold spots” at surprisingly high rates; in summer those spots act as space heaters. In both scenarios they will adversely affect the ambient temp of the room. In short, whatever method you use to heat/cool the room will have to work harder and will take longer. Here’s [0] a good overview of heat flow in this context, with some hints towards the math behind if you wish to go deeper. [edit: add link] [0] https://www.energyvanguard.com/blog/Flat-or-Lumpy-How-Would-You-Like-Y…

> None of this really exists in the residential sector, but maybe it should. The requirements exist in the IRC [1] but are frequently not enforced in many jurisdictions. [1]: https://www.energyvanguard.com/blog/2018-building-code-makes-change-in…

The all-in-one heat pump hot water heater pulls in warm air from its surroundings, pulls the heat out of it and puts that into its water. Then it lets out its "exhaust" colder air. Ducting to outdoors improves things, because it doesn't put that cold air back into your basement / utility closet, but you're still pulling heat out of the air - which your house heater now has to put back into the air - and unless your space is perfectly airtight, that's probably just going to be sucked in via the nearest air gap to outside. It's a bad system. Split systems make sense, and I know they exist, but they seem weirdly rare. Some data on this topic: https://www.energyvanguard.com/blog/will-a-heat-pump-water-heater-free…

This is much less of a good idea than you think: https://www.energyvanguard.com/blog/75600/The-1-Reason-Power-Attic-Ven… A whole house fan is a very different story, but it’s only really useful in some climates.

Indoor air quality means different things to different people. There are so many chemicals and particles that qualify as air 'pollution' that I find it helpful to rank how important they are. This article does a good job of quantifying the damage by pollutant, using a metric called 'Disability Adjusted Life Years': https://www.energyvanguard.com/blog/which-indoor-air-pollutants-matter… You can see that while there are a lot of things to consider, PM2.5 is by far the most dangerous. Surprisingly to me, mold is actually the next most dangerous, implying that indoor humidity control is also very important.

Your first claim was so interesting I had to Google it. But this article suggests it doesn't hold up. https://www.energyvanguard.com/blog/will-shading-your-air-conditioner-… Moneyquote: "The temperature of the surrounding air has a much bigger effect on cooling efficiency than direct solar gain, and the volume of air pulled in by an air conditioner is huge."

I googled this, because I did find it hard to believe, and I think you're correct. According to the below source, for example, heating a home in Atlanta, Georgia throughout the winter months costs about twice as much as air conditioning it in the summer months. [0]: http://www.energyvanguard.com/blog/30576/Heating-or-Cooling-Which-Cost…

Not in a way meaningful to assessing infectious risk, no. I consider outdoor air to be unshared, except in cases of large dense crowds (such as say outdoor festivals or sporting events). I consider risky shared air to be indoor air with one or more other individuals that are not known to be taking infection-prevention precautions. One can measure CO₂ as a proxy to rebreathed air fraction. For example, a CO₂ reading of 2300ppm (common in a small or medium room with a few others, or larger rooms with a crowd or conference room, or in a car) means 5% of your air is rebreathed (5% of your intake is output from another person's lungs). A way to think about this is we take ~20 breaths a minute on average. So in that scenario, it would be equivalent to one breath every minute coming directly from someone else's lungs. If they happen to be contagious with an airborne contagion (such as Covid, or influenza, or RSV), there's a high likelihood that you will catch it if you're spending more than a short time in that environment. There are nuances, such as maybe the air is being scrubbed (eg by a HEPA filter) which won't affect the CO₂ levels but will drastically lower the infectious risk of that environment. More reading: https://www.energyvanguard.com/blog/what-a-carbon-dioxide-monitor-tell…

> No, this is Australia. Houses are more like tents than actual buildings. Pre-AC being ubiquitous (or being invented), the way for people to cool off in summer was to have airflow. Insulation was a more of a cold climate thing, as keeping the heat in / cold out was more intuitive when burning wood or coal: thermal boundaries were more 'needed' when there was snow outside. Having thermal boundaries in your structure didn't make sense when it was as hot inside (due to lack of AC) as it was outside, and it has only been in recent years that people clued into that fact. But unfortunately there's a large stock of housing around that was built pre-clue in. Even now there are people who insist that houses need to "breathe", i.e., have holes / be drafty. They do not: * https://www.energyvanguard.com/blog/Myth-A-House-Needs-to-Breathe * https://www.greenbuildingadvisor.com/article/most-houses-that-breathe-… * https://www.greenbuildingadvisor.com/article/buildings-dont-need-to-br… Buildings need to be as air tight as possible, and be ventilated through mechanical means so that stale air is vented out and fresh air is brought in after being filtered and tempered (via an ERV).

> It was set to 69 and held steady at 67 running for 8.5 hours. It wasn't until the temperature outside broke 36 that the inside temp slowly started to climb. This may be normal. Standard practice, per ASHRAE, is to design for 99% of days, and for the remaining 1% (~4 days per year) the system may have to run 24/7 (either for heating or cooling): * https://www.energyvanguard.com/blog/we-are-the-99-design-temperatures-… * https://www.ba-inc.com/hvac-systems-what-is-a-design-day/ This allows for equipment that is "right-sized", as issues can arise (including premature death of equipment from short-cycling) if they are oversized: * https://www.energyvanguard.com/blog/why-an-oversized-air-conditioner-i… * https://www.cooltoday.com/blog/3-problems-caused-by-an-oversized-air-c… * https://bryantlincoln.com/understanding-the-risks-of-oversizing-your-h… By designing for 99% of the time, your gear should be just enough to handle things.