I’m not sure what happened, but I haven’t been getting notified of questions on Ted’s Tips for months now. I just thought everybody was happy or nobody was reading!
I think I answered the backlog of questions, but if I missed your question, please submit again, and I’ll get back to you ASAP!
For the last few years, I’ve been closely (Evy would say “obsessively”) following the electric vehicle (EV) market, waiting for the “perfect” car. I wanted something compact yet spacious enough to haul my bike or golf clubs. It had to have good range, preferably enough so I could use it with only a single recharge when visiting my folks on Cape Cod. It should be comfortable. It couldn’t cost a fortune. Easy, right?
I had been driving a Volkswagen e-Golf for the last couple years. A friend wasn’t using hers, so I took over her lease. I liked the e-Golf a lot, and would have bought it IF it had more range. But this was one of the early models with under 100 miles of range under the best of conditions, so it was unsuitable for road trips. That was fine, as 99% of the time, I’m only driving locally and could use Evy’s car for road trips.
But the time had come for me to get my own car. The Kia Niro EV looks like the perfect car for me. It is exactly the right size, has a range of about 250 miles. Supports fast charging for road trips. It looks sharp. Has a ton of cargo space and is priced competitively. BUT, it wasn’t yet on the market, and I wasn’t willing to wait for it to come to Pennsylvania. Scratch that off my list, darn it!
The Hyundai Kona Electric, the sibling of the Kia Niro was my second choice. It’s smaller than the Niro but still has ample cargo capacity. Since it shares the drive-train with the Niro, it’s peppy and has even more range (since it’s smaller). It’s similarly priced (mid $30’s before $7500 tax incentive). But again, it isn’t available widely yet. Plus, dealers have been marking it up well above MSRP, and I refuse to support price gouging. So back to the drawing board.
Then Tesla announced the Model Y, their compact SUV. The Model Y checks all the boxes for me except it’s a little larger than I wanted. It’s also more expensive. But it looks like a great vehicle. It has a range of up to 300 miles. Since it will use the Tesla supercharger network, there are plenty of charging stations along the i95 corridor, so I could drive anywhere around here conveniently. A big plus is it’s available in an AWD version, which is a big plus for Evy, who is a Subaru AWD die-hard. Even better, Tesla’s (poorly named) auto-pilot feature and top safety ratings make it desirable for longer trips. Finally, Tesla has a big head start on all the other car manufacturers so their cars are several generations ahead. Unfortunately, the Model Y won’t be on the market for a couple of years (at least!) Darn you Tesla for teasing me so!
Because I really wanted to get a car ASAP, I starting looking at used vehicles. I knew I didn’t want another first generation EV because their ranges were too short. A used Tesla was too expensive. What to do? What to do?
After doing a lot of research, and checking used car prices, I decided that the Chevy Volt was the vehicle for me. Here’s why:
As luck would have it, a local Chevy dealer had a spotless Volt with modest miles on the odometer. They were selling it for a good price so I grabbed it.
I should note that Chevy recently announced that they were discontinuing the Volt, so I think dealers are moving them off their lots. Who wants a discontinued car? Me!
The first thing people ask is: “why not get a plug-in Prius or other plug-in hybrid? The answer is, basically, they suck as electric cars. Every other plug-in hybrid uses it’s gasoline engine at the same time as the electric motors in order to generate a useful amount of power. They were designed as conventional hybrids where the gas engine always runs. When they converted them to plug-in hybrids, which are just hybrids with larger batteries and a mode that turns off the gas engine, they neglected to give them powerful enough electric motors. These things are downright pokey in electric only range!
The Chevy Volt is what’s called a “serial hybrid.” Instead of using the gas engine to power the wheels directly, it’s used only to generate electricity to charge the batteries. The batteries, in turn, power the electric motors. The generator (gas engine) can also feed electricity directly to the motors. The electric motor is the primary drive and has to be powerful enough to do the job of accelerating up to highway speeds and pass safely. The Volt does this admirably. And, while it’s no Tesla, it leaves all the plug-in hybrids in the dust.
The downside is that it still has a gas engine, so the system lacks the utter simplicity of a completely electric car. But for $20,000, it’s a great vehicle. It’s been on the market for a number of years, so Chevy dealers know how to service it. And, as the battery capacity diminishes over time (they all do), it will still be useful because the battery is much larger than a conventional hybrid.
Is the Chevy Volt perfect? No, but no car is. The rear seats are definitely “child sized.” They have decent legroom but the headroom is pathetic. Evy whacked her head on the roof as she entered the rear seat. Ouch!
The cargo space with the rear seats up is enough for groceries, but not big enough for my golf clubs, so mostly I drive with the seats folded down, figuring no passenger would want to sit back there anyway!
Acceleration, while good (~8 seconds), is not blistering. But I’m not a motor-head, so that doesn’t bother me. It’s at least as good as other cars I’ve driven. But acceleration fanatics will find it lacking.
Hybrid gas mileage could be better. Modern hybrids are getting more than 50mph, so the Volt’s 41mpg seems low. I won’t know the “real” mileage until I take a road trip since I drive it 100% on electricity now (infinite MPG!!!) I’ll report back after my first trip.
Overall, the Chevy Volt is a great “gateway” vehicle. It runs very nicely in electric mode, but you have none of the “range anxiety” you have with other electric cars. You just drive it normally and burn no fuel. Until you drain the batteries and the gas engine kicks in. This type of every-day normalcy makes it ideal for those who are looking at having a very eco-friendly vehicle without worrying about “will I get there?” And at their current used-car prices, they’re a “best buy” that I’d recommend for anybody looking to test the electric car waters.
As a baseline, consider that typical homes in the United States consume on average 30–60 kilo-Watt-hours (kWh) of electricity per day (=900–1800 kWh per month) at a cost of $0.10-$0.20 per kWh. Those running on electric heat often double these numbers.
Other items that add considerably to electric bills but are less common:
It’s extremely educational to install a whole-house energy monitor or use an inexpensive plug-in energy monitor to see how much energy each of your devices consume. But watch out, once you do, you may turn into a true energy geek, like me 🙂
I recently received this question on Quora and decided to share the answer with readers there as well as on TedsTips. I hope this will save some of you from heartbreak after your winter vacation!
A primary consideration in cold climates is pipes freezing. It is very important to realize that pipes can freeze even if the home temperature is above freezing due to the locations of the pipes. I once owned a townhouse where the pipes would freeze when the outside temperatures dipped into the single digits outside, even though we were warm inside the house. How? The pipes ran up through an inside wall, across the ceiling and over to an outside wall spigot. The inside wall, at the top, opened to the cold attic, so that cold air would get into the wall cavity and freeze the pipes. This was fixed by air sealing the top of that wall cavity, but required considerable detective work to figure out. The pipes running through the outer wall down to the spigot would freeze near the spigot where the pipes were exposed to cold temperature, so this run had to be isolated from the rest of the house plumbing and drained during the winter.
These are two examples, that show potential issues that are made worse by turning down the temperature while you are away. Imagine the situation where the pipes don’t freeze when the house is occupied and the walls are warm enough to keep the pipes from freezing. Now, imagine reducing the indoor temperature, maybe only a few degrees, but enough that the cold from the outside overwhelms the meager heat coming from the house that is able to reach the pipes. This has bitten many a homeowner during winter absences.
Unfortunately, there is really no way of knowing if this will happen until it happens. This is why it is critical that you turn off the main water valve for the water supply to your spigots in your house when you travel*. The pipes may still burst, but at least your house won’t flood. When you return after winter and turn the water back on, you’ll know quickly that there’s a leak and can turn off the water and fix the leak before catastrophic damage is done. This is no exaggeration – I was called into a home that was literally FILLED with mold and had to be gutted. A pipe had burst and the owner returned after a month to find the house completely flooded.
*I was reminded (see comment below article) that you MUST NOT turn off the make-up water supply if you have a boiler for heating your home. This is very important. Boilers need available water to maintain system pressure in your radiators etc. Without make-up water, the pressure in the system can drop and the system will stop functioning.
If you plan on leaving your home for an extended period, it is always a good idea to have your HVAC company give the heating system a once-over to ensure that it is in good working order. While there, they can advise you on which water valve you can safely turn off and which you should not touch. It would be advisable to label all the valves for future reference.
Flooding is the most damaging effect, but there’s another, more insidious issue that can arise during winter house shutdowns – condensation damage and mold.
Condensation can lead to mold and wood rot
In order to understand this, I have to touch on the physics of condensation. Condensation is the conversion of water vapor to liquid water that occurs at or below what is called the “dew point.” At normal temperatures (say 70F), condensation rarely occurs during the winter because the home humidity level is modest and most of the inside of the home is above the dew point. However, even with typical indoor humidity levels, you can experience condensation on windows, because windows get much colder than the insulated walls of the house. You might have noticed this if you have curtains or insulating blinds. These help keep your room warmer but allow the windows to get even colder because they intentionally reduce the windows sapping heat from the room. When you open the curtains, you might find the windows soaking wet from all the condensation. Worse, the wood around the window, especially at the bottom edge, might be saturated with water.
Under normal circumstances, you would see this in the morning and could dry off the wood and allow it to warm up when you open the curtains. But when you are away, even if you don’t turn down the thermostat, the water will remain and can get worse every day. Over time, this will likely lead to mold growth and if allowed long enough will rot out the wood. For this reason, I highly recommend that people leave their curtains and insulating shades “UP” or “OPEN” when they are away for extended periods. You want to minimize the chance of condensation buildup and the associated potential for mold and wood rot.
Let’s continue this thought experiment. If you turn down the thermostat enough, the inner surfaces of your house (walls etc.) can get to a temperature below the dew point and, just like those windows, the water vapor in the air can condense on those surfaces. Many people have made this mistake and come home to a horrible, moldy mess! For this reason, it is extremely important to do two things:
1 – do not turn down the heat excessively. It’s impossible to tell exactly what temperature is too low, but in most climates, people find 55F-60F is safest.
2 – make sure you don’t add any moisture to the air while you are gone. This can be disastrous. For example, many homes have central humidifiers built right into the heaters. If you leave this one it raises the humidity level inside the house every time the furnace runs, likely leading to moisture problems. Turn off all humidifiers before you leave!
Even if you don’t have humidifiers, natural ground moisture can seep into the house through the basement, crawlspaces, etc. This is especially common in homes with dirt floors underneath. Water vapor rises up into the house, driving up the humidity. If you live in such a home, it is really important that you monitor the humidity levels in the home to ensure that they are not too high. During winter, indoor humidity levels will naturally be low, typically less than 50% relative humidity. Humidity levels above 70% are considered too high as they promote mold growth. Get yourself a humidity monitor (they’re cheap on Amazon) and see what humidity levels are. Or better yet, get an Internet smart thermostat.
Get an Internet connected thermostat that monitors temperature and humidity
These let you to monitor indoor temperature and humidity levels while you are gone. These are affordable nowadays, and can give you tremendous peace of mind. A quick daily check on temperature and humidity gives you a read on the health of your home. It’s not a guarantee, as you still might have condensation problems, but at least you can be sure that the general climate inside your home is reasonable. It will also tell you that your heating system is working. If the temperature suddenly drops to 45 even though your thermostat is set to 55, you know there’s a problem and can call in help.
Have a wonderful winter. Hopefully you will avoid the main pitfalls that have hit too many other people. A few easy steps can greatly improve your odds of coming back to a healthy home!
A reader, Adam, recently asked about the pros and cons of using LED retrofits vs. sealing recessed lights from the attic. It’s such a good question that I had to write up a quick post detailing my thoughts on this important topic.
I’ll start by saying that I have upgraded all of the recessed lights in my home with LED retrofits. This has numerous benefits over attic sealing. Prior to good LED retrofits being available, I had constructed airtight/fireproof boxes installed from the attic, so I can comment on both methods from first-hand experience.
The retrofits were easy to do, taking maybe 10 minutes each, at most. These days, high quality retrofits are inexpensive, typically less than $30.
A picture is worth a thousand words…
Air-tight? Not unless installed right!
Almost everybody gets thrown off by this, but I moderate comments to avoid spammers. The downside of this is that you won’t see your comments post until I’ve had a chance to review and approve them. Sometimes this can take days (sorry!) Thanks for your patience.
2017 Chevy Volt
In short – probably not. Unless it’s a Chevy Volt. Why? Read on! (Update, Sept 12, 2017 – Honda announced their new Clarity plug-in which sounds like it will give the Chevy Volt a run for its money! Update, Sept 14: Maybe not. Driveability sounds so-so and based on this article, you only get 121hp in EV mode 😦 ).
Virtually every auto manufacturer has pledged to electrify their product lines before 2025. This could mean making all their cars hybrids, like the Prius. But many are mentioning at least some of those cars will be “plug-in” hybrids or fully electric vehicles.
In previous posts, I’ve discussed the great benefits of pure electric vehicles – great drivability, simplicity of drivetrain for minimal maintenance, zero exhaust pollution, and never having to go to the gas station. I’ve also written about the difference between the types of electrified vehicles, but I haven’t done a deep-dive into plug-in hybrids. In all likelihood, you’ll be seeing many vehicles with this label in dealer showrooms, but what exactly do they mean? Hopefully, by the time you finish reading this post, you’ll understand and be able to purchase your next vehicle, confidently knowing exactly what you’re getting.
Plug-in hybrids are hybrid vehicles with larger batteries and a switch that allows you to change them from gas-electric propulsion to electric only. “Great!” you might think – “best of both worlds! Now I don’t have to worry about the range of the batteries since I can always switch on the gas engine.” However, all is not so rosy. As with everything in life, there are compromises. Continue reading
There’s been a lot of talk and press coverage about electric vehicles the last few years. Tesla, Elon Musk’s electric car company, has generated huge excitement with it’s sexy, high performance cars, but their price has put them out of reach of most consumers. The Tesla Model 3, to be released in mid-late 2017, hopes to change that however, giving you a 200+ mile range electric car for under $40,000.
Tesla isn’t the only game in town. Chevrolet released their sub-$40k Chevy Bolt at the beginning of 2017, and this compact SUV shaped electric vehicle has won accolades from all the automotive press, setting the standard for high range (200+ miles on a charge) vehicles.
These two are just the start of a flood of EV’s hitting the market. Virtually every auto manufacturer has promised a variety of electric vehicles – great news for consumers, but also potentially confusing.
In this article, I hope to arm you with some useful information so you can decide if an electric vehicle is right for you. Continue reading
Intuitively, clean solar panels are more efficient than dirty ones. But how much of a difference does it really make?
Like you, for years I have read that you *must* clean your panels because dirty panels waste so much sunlight. Since you’ve paid lots of money for your panels, you want every Watt that they can produce. But how much of a difference does it make?
This spring, after the flowers and trees sprayed their pollen everywhere, my panels were really dirty, totally covered with yellow pollen. I figured, this must be costing me big in solar production. So, being an energy geek, I decided to measure the output before and after cleaning (on consecutive days with clear skies at the same time).
In short, I discovered that, even this dirty, there was very little measurable difference. With my big array, when dirty, I got 8.4 kWh at the noon hour. After cleaning, around 8.5 kWh. However, the effect was so small that I think this measurement is within the margin for error since even a little change in conditions would make a greater difference.
Given the time and potential danger of climbing on the roof, hosing down the panels and cleaning them properly, this tiny difference hardly seems worth the effort. Certainly, it isn’t worth the several hundred dollars that a professional cleaners would charge, especially considering that the panels will just get dirty again after another week!
There are conditions when you should clean your panels. If you have a flat or very low slope roof in a dry climate, the dust can form a very thick layer that isn’t washed away by infrequent rains. Over time, the dirt will cake on, making it harder and harder to clean. Periodic maintenance makes sense in this case.
As part of this experiment, I discovered that my solar panels were producing far less energy than expected. In the past, I had measured over 9.5 kWh for the noon hour. At other times, they produced less than 8.3 kWh. This is a *huge* variation! But why?
After some research, I learned that solar production decreases when the panels get hot. So I went back through years of solar production records from my system, picked days that had full, uninterrupted production (no clouds) and graphed it. Here’s the results:
First, I must explain why there are two lines. The bottom level, ranging from a max of 8.4 kWh to 7.4 kWh are the data from before my solar system was expanded. The top line is from after additional panels were installed.
Next, I admit that these are crude measurements because they are based upon the daily average temperature at my location. Ideally, I would put a temperature sensor on a panel, so I could measure output vs. panel temperature. However, the effect is nonetheless very strong and paints a clear picture – solar energy production drops very significantly as the days get hotter.
If you are paying attention, you will think – “when the days are colder, isn’t that winter, when the sun is much lower?” The answer is “YES!” My data were chosen between mid-March and mid-August of several years. You would think the June numbers, when the sun is highest in the sky would produce the most energy. Not so! Temperature clearly makes a much bigger difference than this amount of solar angle change. In fact, the best noontime production was in mid April, where the temperature is low and the sun is bright.
Please note that this is the peak hour production. The total day’s production, for my fixed mount system, is when the days are longest, even though the temperatures are higher. But I think it is useful for others to understand how much of a difference heating makes to solar production. So if you see your system underproducing during a hot summer day, that doesn’t mean it is malfunctioning. This can save you the pain and frustration of a service call.
The important thing that this implies is that a ground mounted system, with open backs and plenty of air flow as well as the naturally cooler temperatures of the moist ground below it, may be better for production than roof mounted, with very little natural air flow and a hot roof. Someone needs to study this, given how large a difference temperature makes to production.
In the first article of this series, I discussed a lot of the theory behind attic insulation that you should know before taking on your insulation project. If you haven’t read it, please, click the link and do your best to understand the basics before proceeding.
This house definitely has problems
This winter, most of the questions I’ve received have been about moisture buildup in attics or cathedral ceilings. And all have the same answer – humid air from the house is rising up through all the little cracks and holes in your ceiling. Once it gets into the attic space (or the space between the roof and the ceiling of a cathedral ceiling), the air cools rapidly and the water held in the air condenses on to a near-by cold surface – usually the underside of the roof or the roofing nails.
Once this happens, the water drips into your insulation or soaks into the roof sheathing. If this happens once and dries out, it’s no big problem. But during the course of the winter, this happens again and again, and before you know it, it’s raining inside the house as water leaks through holes in the ceiling.
There’s a saying – “there’s no such thing as a small water problem.” But often people will try to put a band-aid on them. Unfortunately, every day a water problem is neglected, is another day closer to serious structural problems and tens of thousands of dollars of repairs. So it is in your best interest to deal with water problems as seriously as if your house was on fire. Deal with it today, or you’ll be really sorry tomorrow.
Let’s look at the underside of a roof that has experience this repeated wetting from condensation:
Fiberglass insulation against roof deck in an attic leads to roof failure
Moldy roof deck above a cathedral ceiling
The first thing knowledgeable people ask is: “will adding more ventilation eliminate the problem?”
We’ve all been told that you have to have air flowing through the channels, from the eaves (soffit vents) up to the peak (ridge vent) in order to flush out the moisture. But this is only part of the story and it doesn’t guarantee anything. In some cases, it makes the problems worse.
The purpose of insulation in winter is to slow the heat loss from the house and out the roof. Take a look at the photo at the top of this article. Half the roof has snow, the other half does not. The half where the snow has melted is a clear sign of heat loss from the house. The heat warms the roof sheathing and melts the snow.
Recall what you know about condensation – condensation occurs when moisture in the air comes in contact with a cold surface. The roof is above the insulation, so it’s supposed to be cold. If it were warm (like the right half of the photo of snow), then condensation would be less likely. The situation is a Catch-22 – good insulation equals cold roof. Cold roof plus humid air equals condensation. Ugh!
Given these conflicting issues, what do you do?
U.S. EPA Air infiltration poster
The answer is simple – reduce the amount of humid air that can come in contact with the cold roof.
In the winter, almost all the moisture comes from inside the house. It rises up, along with the warm air, finds every tiny crack in the ceiling, and gets up into the attic or inside the cavity under a cathedral ceiling.
The first thing you want to do is reduce the amount of water getting into the air from inside the house.
The most common source of large amounts of moisture is the shower. When you shower, you create a “worst case” scenario – hot water saturates the air. That “super saturated” air will immediately dump the humidity onto any cooler surface it touches.
When you shower, you must run the bath fan during and after your shower until the all the excess moisture in the bathroom is flushed out. Usually, this means allowing the bath fan to run for approximately 30 minutes after you shower.
If you have a door on the bathroom, keep it closed until all the moisture is flushed out. Never shower with the bathroom door open because the moisture will flow out into other areas of the house that are not designed to eliminate the moisture.
Far too often, dryer vents take long paths to get outside. This leads to inefficient or even dangerous operation. If your dryer takes forever to dry clothes, chances are good that it’s not venting effectively.
Don’t even think about getting a dryer “heat reclamation” device. These pump gallons of humid hot air into your home, greatly increasing your odds of mold and roof rot.
If you have moisture problems and you use a humidifier, stop using the humidifier. Humidifiers can dump gallons of water into the air every day. Central humidifiers are especially bad because they use the homes leaky ductwork to spread the moisture.
If you absolutely must use a humidifier, use it only in the room where you sleep and turn it off when you’re not using it.
Keep in mind that the primary reason you need a humidifier is because your house is leaking in cold, dry air. The need for a humidifier is a clear sign that your house is inefficient and you could save a lot of money and be much more comfortable by tightening your home. I know – when I moved into my home, our lips and skin cracked, our noses bled and we were really uncomfortable. We had to use humidifier round the clock to be comfortable. After replacing our old windows and air sealing the house, we haven’t had to use the humidifiers once.
If you cook on the stove a lot, make sure you use an outdoor venting range hood. This is especially important if you have a gas stove or oven because these generate carbon monoxide and water vapor.
Much of that water you use to water plants ends up inside the house.
These should be outlawed. Ventless gas fireplaces generate tons of water vapor and, if not running cleanly, carbon monoxide, which can kill you. No matter what Bob Villa might say, these units should never be installed or used. It’s physics. A byproduct of combustion is water and carbon dioxide. And if the combustion isn’t *perfect*, you also get carbon monoxide.
If you have a crawl space or damp basement, this could lead to huge amounts of moisture entering your home. Many articles have been written on this topic. For now, be aware of this and check your basement and deal with any moisture problems under the house. If you don’t there’s a good chance you’ll end up with attic/roof moisture problems.
Self explanatory.
I’ll save myself 1000 words – refer to this excellent diagram and ensure that your home has an airtight seal between the living space and the attic or the inside of your cathedral ceiling.
If you’re considering (or already have) recessed light fixtures, use air tight LED fixtures. The manufacturers completely lie when they label traditional fixtures as ICAT (insulation contact, air tight). I dare you – turn one of these fixtures upside down and fill them with water. Water will rush through all the holes in the fixture. Now picture your ceiling during the winter – air flows right through the fixture, carrying moisture up into your attic or ceiling. You are virtually guaranteed roof rot if you have a ceiling filled with recessed lights.
Don’t believe me? remember this photo from earlier? This builder swore up and down that he did everything right and the roof was still rotting. Why? Because he installed about 20 of these fixtures in the ceiling. You can’t argue with physics.
Fortunately, you can cut your energy usage in quarter, never have to change a bulb again, and eliminate the moisture infiltration problem by using flush-mount LED lights like these. You can also retrofit existing recessed light fixtures using these types of lights.
One word of advice – use a thin bead of caulk around the lip of the fixture to seal it to your ceiling. This is the only way to ensure an air-tight seal. Yes, it will be a pain in the butt to remove later, but these things are rated to last 36,000 hours. That’s 4-years of continuous use so 10-20 years in real use. LEDs often last much longer.
I have never seen a bath fan that’s properly air sealed, and they’re in the most critical location in the house. The installer will cut a hole about 1″ larger than the fan then cover up this big gap with the fan’s grill. Out of sight, out of mind.
All that humid air from your showers will go right up through these gaps and into your attic. This is the place you should start with your air sealing because it’s so easy and so effective.
After that, if you have heating/air conditioning vents in the ceiling between the living space and attic, remove the grills (called “registers” in industry lingo for some reason). These are installed the same way as bath fans. Big holes. Sloppy installation. You can use spray foam or caulk to seal the gaps. Or, use this incredible tape, called “foil mastic.” Clean off the sheet metal of the duct “boot” (that’s the metal thing the duct is attached to that screws to your ceiling). And use this tape to seal all around the perimeter where the boot attaches to the ceiling. Be careful to measure it so that it doesn’t show outside the register before sticking it to the ceiling because once it sticks, it’s on there for good!
Attic hatches are responsible for a huge amount of energy loss and the associated moisture damage in attics. Make sure yours is air-tight (which is almost none except for these Rainbow attic stairs). These are the best I’ve ever seen and worth the money.
For the other 99% of you who already have attic stairs, install the ESS Energy attic stair hatch. This thing is awesome. Or, you can build your own out of foam-board. But seriously, the ESS Energy system is so much better than the other solutions out there that’s it’s worth it.
The best way to go about air sealing is to have an energy auditor come and do an infrared inspection with blower door test before and after the project. You do it before the air sealing to locate the air leaks so you can prioritize the work. You do it after to ensure the work was done right!
When I did these inspections on a daily basis, I found that the combination of blower door test and infrared thermography was the only reliable way of finding the problems. Some folks will say they can find all the problems without the right tools, but, frankly, they’re misguided. I don’t care if you’ve been doing this for 50 years, your eyes are not going to find hidden problems.
Let me give you an example. Suppose you go to the doctor. You’re not feeling well. Strange pains in your abdomen. If the doctor prodded you a couple times, told you “it’s nothing, you’ve got gas” then said “I don’t need to use a newfangled MRI machine” – would you trust your life to them?
For a few hundred bucks, are you going to trust someone’s eyes or a proven tool?
After you’ve reduced humidity problems in your home, then air-sealed the ceiling between the living space and the attic/cathedral ceiling, then you can insulate.
How should you insulate? Honestly, if you’ve done your prep work properly, you can use cellulose, spray foam, fiberglass, recycled denim or horse hair and your home will be relatively well insulated and energy efficient.
Obviously there are differences, but it should be clear that the prep work for insulation is key. Even the best insulation product can have issues if you don’t air seal and reduce humidity.
I have to start by saying this is all for winter insulation. Hot, humid climates have their own rules which are often reversed from cold climates.
In winter, the moisture barrier should be the first thing beyond the ceiling material. You absolutely don’t want to trap moisture on the cold side of the insulation.
Refer to your local building code for the use of moisture barriers. Many jurisdictions are changing their approach to moisture barriers.
Like I said, the specific insulation product usually doesn’t matter if everything to this point has been done right. The main differences between products are price, R-value per inch of thickness and convenience of use. These can be significant differences and you have to determine what works best for your own home.
Rotten roof deck caused by moisture trapped by insulation
If you’re installing insulation directly under the roof, like in a cathedral ceiling or attic ceiling, make sure to leave about a 2″ gap between the insulation and the roof sheathing. If you don’t, there’s a good chance your roof will end up like this.
Ok, that’s enough. My fingers are tired from typing all morning. If you’ve read half of this and gotten this far, you should have most of the information you need to create a comfortable, efficient home that will last for decades.
Ted's Energy Tips 