The NCAA championship is over but that doesnt mean basketball is done for the season. The NBA Finals start tomorrow. In the spirit, it's always fun to talk about who the greatest team was in any sport, or if you had free reign to pick any combination of players from any era to be on the same team. Who would make the best team? Jordan? Lebron? Kobe? Oscar? Chamberlain? Bird? Russel? Magic? Kareem? or many others not listed here. So much talent but who makes the cut? We all have our preferences and loyalties, thats what makes these conversations so fun.
I only hear these sort of talks around athletes and the occasional truck talk (put a Cummins in an Ford with an Allison Tranny yada yada yada), so lets talk contractor world and the homes we live in. Im no expert when it comes to building a super energy efficient home but there are some builders and engineers out there that provide some direction on what might make the perfect team (or home). Builders like Mandalay Homes who continue to drive performance and what an energy efficient home should be and organizations like NAHB that test and showcase the most innovative new products for building a home are good resources to get started.
*Just a friendly disclaimer, these are my personal thoughts on what my list would be and there is no hard data to prove why one is more important than any other or why a particular product didnt make the list.* In the research I have found, a tighter home (meaning less air infiltration) correlates to a more efficient home if all other variables are held constant. This is because our heating and cooling costs are typically our most expensive and cutting down on air infiltration means you have more control and arent fighting to constantly condition outside air. For instance two homes next door to one another in Arizona with the outside temperature consistently around 90 degrees F, one has an air leakage of 7 ACH50 (Air change per hour) and the other has 3 ACH50 but all appliances (High efficiency) are identical, same windows and doors, and same layout of the home. Literally, the same everything but air leakage levels. If both set their thermostat to 72 degrees and go on vacation for a week, or lets stretch the imagination and say for an entire month. That means windows and doors remain shut, system runs at 72 degrees and we have our constants in place. When the families come home from vaca they will find different utility bill amounts for their month of energy use. So it really doesnt matter how efficient the products in your home are if you are constantly fighting against the outside elements that produce inconsistencies.
And while you could certainly make the case that a 7ACH50 home with all high efficiency products could perform as well or better than a 3ACH50 home with outdated technology, the amount of investment in those appliances and higher end windows/doors would be insignificant compared to the potential of a tighter home. Sure you can build a net zero home that has a higher leakage but how many acres do you have to cover with solar panels? Or you could opt for the lifestyle of olden day and completely cut out electric all together. I am going to go out on a whim and say that either situation is out of question for the majority of us. Below is my list of what would go into a Net-Zero home if money wasnt an object and I wanted the most efficient system; meaning not having 5 acres of solar panels.
The Starting 5 for the NET ZERO Team
ERV - Not necessarily the star of the list but without this, there is no team. Meaning in order to get a super efficient home it needs to be tight. Unfortunately, tight isnt always right. The home needs to breathe or it will be more problematic than beneficial and so, once a certain air tightness is achieved (below 3 ACH is a good rule of thumb) you need to mechanically bring in fresh air from the outside to make up the difference. For example, a leaky home brings in outside air with all of its properties (temp and humidity). So if its 20 degrees outside or maybe 90, that is what your heating/cooling system is constantly battling as it maintains the 72 on your thermostat. With an ERV, the indoor temperature is all that matters because the system mixes the the two (indoor and outdoor) to bring in air qualities closer to what is already inside. Meaning, instead of 20 or 90 degrees coming in itll be closer to 55 or 80 which allows your system to more easily condition the new air. For this reason, the most efficient net zero home will absolutely need a ventilation strategy and that is where the ERV comes in. It is set to operate on a schedule or automatically function when There are sensible systems that simply transfer the temperature of outdoor and indoor, then latent recovery systems that actually take into account the humidity. The Latent ERV's will be the most effective from my understanding as it removes the humidity meaning the HVAC system will operate under a reduced load. Less load means less tonnage required of your HVAC system and that means less cost to you as the homeowner.
Tesla Solar Roof - Solar doesnt work in all climate zones with the same effectiveness. But if the sun were readily available as it is in Arizona, there is no question... Solar would be included in my home. Now builders are learning ways to build super efficient homes that require much fewer solar panels than ever but it still doesnt mean I like the look. Tesla has come up with a solution that achieves the solar production you need while seamlessly integrating with your roof. Sure you are probably going to be able to tell the difference if you stare long enough but if you were just driving by I doubt you would notice anything out of the ordinary to draw your attention. So before you had these big bulky solar panels sitting on top of your shingles and you really wanted the least amount possible to keep a nice look, now you can effectively use all of your roof to harness solar without sarificing the appearance of your home.
Tesla Storage - Hand in hand with solar or any other renewable energy source, storage makes the most out of what you produce. When you are producing more energy than you are consuming, it needs to go somewhere. If you have already set an agreement in place with your utility provider that they will buy back your surplus energy production then you may feel thats enough. However if you have not made an agreement with them and you dont have a storage system, you just paid a bunch of money to produce a whole lot of energy that cant be used and its essentially wasted. Sure you arent paying anything on your bill but wouldnt it be icing on the cake if you could 1) harness that excess energy production and 2) make money off of your excess and unused energy. For instance, the roof system above integrates into a Tesla Storage Unit so you can power your car, batteries, external devices or anything else, or store a surplus of energy that you have produced to sell back to utility companies or save in case a storm knocks out your power. The storage unit can also rollover energy so say one month you have a surplus and then the next you didnt. There might be enough stored energy to cover the difference meaning you end up owing nothing. Needless to say, a storage unit is crucial for a net zero build. In the picture above, the storage units are those things on the wall in the garage. As you can see, not too space consuming for the benefits.
AeroBarrier Envelope Sealing - Pretty youthful along with the shingles, this innovation seals it all. If you want a home that is sealed tighter than any human could get by hand then you have found the answer. To relate this technology in the simplest way possible, think about fix-a-flat for your tires except now for your home. Maybe that sounds crazy but its real. This seems to be the easiest and most practical solution when a home is in the construction phase or you are gutting the home for a rehab. AeroBarrier comes in and uses a blower door, the same equipment that is already being used to certify your air tightness to meet code, and sets up nozzles inside of the home to disperse the aerosolized sealant, then a computer controls the entire process. Home is pressurized, sealant is released, and the positive pressure pushes the sealant to any leak without covering the entire space. By hand you are left wandering around the home with a caulk gun and in many cases, hoping you covered all the leaks. With AeroBarrier you don’t need to worry if the contractor missed anything because the pressurized air finds EVERYTHING. It’s also low VOC and GreenGuard Gold certified so you can trust that the solution is not toxic and good for IAQ (indoor air quality). The only drawback to this product for a homeowner when compared to the others on the list, while it can be applied to existing homes that are currently being lived in, it really isn’t practical. You would need to remove all furniture and decorations, TVs and electronics, cover all your beautiful surfaces (granite countertops, carpet/tile/hardwood, and really anything inside of the home that could interfere with pressurizing the space or that you don’t want to risk damage to). If you are building new or gutting a project, I would strongly recommend looking into AeroBarrier.
Owens Corning Blown In Cellulose - Every home needs insulation. AeroBarrier is not an insulator just a building envelope sealer that greatly minimizes the amount of air infiltration so you still need something for the wall cavities. While many believe spray foam to be a great product because in theory it should do it all; it expands to perfectly fit each wall cavity meaning it should both stop air infiltration and provide a dense layer of insulation for the greatest R-value. Unfortunately, its inconsistent from contractor to contractor, it doesnt stop the air infiltration as effectively as you'd think and the chemical makeup along with off gassing just isnt healthy. Blown In Cellulose doesnt off gas and provides nearly as good of an R-value with less cost on you as the homeowner and better air quality. The other thing about insulation that I think many people, especially those I have spoken with, fail to realize is that stuffing and packing insulation into a tight space is not what you want to do. Insulation is most effecient when it is left open and fluffy because it will capture more of the heat loss where stuffing insulation provides more access to move around the insulating properties of the insulation. I know it sounds counter intuitive, less is more, but over compressing the insulation will diminish the R-value. So while R-13 or R-15 will work on a 2x4 framed wall, please dont try to force R-19 into anything less than a 2x6 framed wall. Nothing against spray foam, but between the two I would personally choose blown in.
Dont let "the bench" ring as anything less than great. Every team needs depth to prevail and it would be an honor for anyone to make the bench for the greatest team of all time. Think of it more as the top 9 out of everything available rather than the bottom 4 of a list of the best performers.
Aeroseal Duct Sealing - Whether your ducts are or are not in a conditioned space, the fact is they leak in almost every case. And while they leak, its sometimes impossible to get to all of the leaks for many reasons; existing walls or structure, time constraints of doing it by hand (does the amount of labor justify the added result), unoticeable to the human eye, etc. In the end, Aeroseal is an approach that gurantees the results, seals everything from the inside based on pressure therefore doesnt discriminate (if there is a leak, it will find and seal it), and does all of this in significantly less time than the manual way of masctic and duct tape. If you are in an existing structure and your duct work is behind walls or in hard to get places you would historically need to tear out the drywall to get to it and seal. Not anymore. So you get a better end result, less time is needed by the tech in your home, the work is guranteed for 10 years by the manufacturer (you wont find that guarantee with any hand sealing), and you dont need to worry about replacing duct work or drywall in almost every case.
GeoThermal System - This system is pretty much hidden so it doesnt take up much space inside the home. Majority of it is in the ground around your home afterall. Collect free heat from the Earth and reverse the cycle during warmer months to push unnecessary warm air back into the Earth. The only big cost is the upfront cost but when you arent using energy from a provider, you arent paying anything. Last I checked, the Earth is not charging any of its residents to use what is there. Your heating bill, especially when using electric instead of gas, can be very costly depending on what climate zone you are in. GeoThermal is the cheapest and most effective way to maintain comfortable indoor temperatures at a near zero cost. The only cost with the system that I can think of would be anything electronically controlled in the duct system to make sure it pulls in or pushes back the air. The Earths temperature at the depth of the geothermal piping also stays pretty consistent year round so you should not worry too much about a heat wave or freeze alert.
Zip System Continuous Insulation Sheating - This would have made the starting list had AeroBarrier not been available. The Zip System truly does a wonderful job of keeping air out and creating a tighter home envelope which should correlate to less energy use since you wont be conditioning outside air continuously. With normal plywood sheating, the pieces lie next to one another and then a weather proofing goes over it. In theory that should be good enough right? Where the pieces butt up to one another there is a 2 by material they split so no loss. Well yes, on the vertical side. The horizontal side does not as it spans between studs. So we add a piece of plastic between the framing and outside sheathing. It gets a good portion of the leakage but it still leaves your home meeting the minimal code for living occupancy. Not even close to Net Zero, let alone LEED. So the Zip system was born to tackle this overlooked problem. A continuos system that significantly minimizes the amount of air infiltration. It also comes in an R-3 or R-6 rated offering to provide a better R-value to your home. If its in the budget, both this Zip System and AeroBarrier would create a very, very tight home I think.
Quadrupile Pane Windows - You heard that right! Or maybe you didnt because your yelling through 4 panes of glass. Just when I thought triple pane were the latest and greatest, turns out the anty has been upped again. Give me 4 panes of glass to keep any air from making its way through along with the noise. Put a low-e glazing on these and youll have minimal heat transfer for enhanced comfort. Quality is still always going to be the issue as 4 panes of glass doesnt gurantee you any results and its the construction of the frame/sill/chambers/etc. that have a bigger role. We can all agree that air isnt making its way through even a single pane of glass (unless there was a hole), leaving the air to find its way in around the glass if there are entry points. Dont let someone fool you with more is better until you research and understand the quality. Kind of like putting a strong motor (the glass) thats proven onto a chassis (the frame) with a history of failing. Its easy to lose sight with the more is better but look at the bigger picture when deciding. And while you may be worried about weigth because glass isnt light and no one wants to deadlift their windows open or worry about them staying open under that pressure, windows these days have very good parts that make opening and closing a breeze. They make constant force coil balances that are incredible for windows and these balances act the same way as hydraulic lift supports help when opening the back of an SUV. Anyone who has had these fails quickly learns how heavy that door really is.
If the stats arent enough to make you a believer once your dream team comes in and builds your home, feel free to test it. Get a home health consultation from a specialized local HVAC company to swing by with their IR cameras, blower doors, flow hoods, negative pressure tests and more to show you just how efficient your home really is. And even if the dream team didnt build your home and your just living in an averagely built home like myself, you can still get this home health check to see if maybe you're just missing insulation in certain areas, maybe your ducts are leaky or the equipment isnt properly sized or balanced. Whatever the case is, if your team at home isnt performing... it would be in your best interest to get them checked out to see why.
So what does your team look like? Comment with ideas.