Category Archives: Windows

What Temperature Should I Set the Thermostat to When Away for the Winter?

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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.

Water and Ice on a Cold Window

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.

Smart Thermostat with Relative Humidity

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!

How to Install House Wrap around a Window

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Proper flashing detail around a window

Proper flashing detail around a window

When I head out around the countryside, I am frequently dismayed by all the examples of improper construction techniques. “There’s another house that’s going to rot out in a few years” I think to myself.

So, when I saw this new construction, I did a double-take. Did the contractor actually properly install the house-wrap (Typar or Tyvek) around the window? Amazing!

Let’s look at what they did right:

  1. They used Typar house wrap which is generally a better product than Tyvek. But installed correctly, each can do a fine job
  2. They installed the house wrap horizontally in long, continuous segments. This reduces the number of seams, which are potential failure points.
  3. They used the Typar tape for the seams. This is a little detail that is often missed. The house wrap is slippery material and using the wrong tape on the seams can lead to failure. Only the factory approved brand should be used whether it be Tyvek or Typar.
  4. *IMPORTANT* They sliced the wrap above the window and installed the top piece over the window’s nailing flange. This directs water properly. 90% of the installations are done without this detail which leads to water getting under the nailing flange!
  5. *IMPORTANT* They taped the wrap under the nailing flange and over the bottom sill. Again, this is critical for proper drainage. If water gets behind the window, it drips onto water-impervious Grace Vycor then drains out at the bottom flange. Most installers tape the bottom flange to the house wrap which traps water inside the wall.

So kudos to the builder. This home is much less likely to rot out than 90% of the other new constructions!

Quickie tip of the day – warm up a room by closing the curtains

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Reduce heat loss by up to 75% using cellular shades

Reduce heat loss by up to 75% using cellular shades

Yet another day of near record cold here and I realized that most of the winter I’ve been neglecting one of the simplest things I could be doing to warm my rooms – closing the curtains!

Yes it’s true – even The Energy Geek forgets the basics.

Why is closing the curtains so important? That little air gap between the window and curtains acts as insulation and can cut the heat loss out your windows by half or more. This is pretty significant when you consider that the windows may be sucking more heat out of the room than the walls.

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How to diagnose your high heating bills and drafty home this winter

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Part 1: Introduction to Winter Energy Audits

Here in the mid-Atlantic and Northeastern U.S., we’re getting hit by another deep freeze. Those in the center of the country are probably thinking we’re wimps for complaining about single digit temperatures, but hey, it’s all relative. For us, it’s darned cold!

I’ve been getting a number of questions recently, spurred on by the low temps and associated HIGH heating bills. People are asking: “Help! I got my latest heating bill and it’s astronomical. What can I do to reduce it?” or, the other side of that coin is: “Brrr! My family is freezing. I’ve got the heat cranked up but it’s still cold and drafty in some rooms. What can I do make it more comfortable?”

We’re going to walk through a virtual energy audit “live” so you can follow the thought processes and troubleshooting with me. Hopefully, this will allow many of you to go on to diagnose your own issues and end up with a home that is more comfortable, efficient and safe.

Along the way, drop your questions into the comments below the posts, and I’ll do my best to incorporate answers into the article or answer them in the comments.

Let’s get started!

Edit: rather than doing this as one humongous post, I’m going to break each section into a different post. This should make it easier for people to find the pertinent information and step through the process without it getting too overwhelming.

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Why do I have condensation in the middle of my windows?

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A Sure Sign of Collapsed Glass

Collapsed Glass Syndrome

I was recently visiting my brother and he pointed out a strange condensation effect he was having on some double glazed windows. Condensation formed in an oval pattern in the middle of the windows. This is really strange because condensation forms on the coldest parts of windows first. Thermal windows usually insulate best at their centers so condensation starts forming at the edges. But these windows were showing exactly the opposite condensation pattern as shown in the photo above.

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Is condensation bad for windows?

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Bathroom windows will almost always "sweat" in the winter

When cold weather sets in, I invariably get a slew of questions from people worried about their windows “sweating.” There’s a perception, propagated by window salespeople, that condensation is a  sure sign that you need to buy new windows for your home. What’s the truth?

The photo above is of a north facing garden window in my master bathroom. In general, I keep the humidity quite moderate in my home but this window definitely shows more condensation than others. In this case, during a spell of temperatures in the low teens, a layer of ice even formed. Should I replace this window?

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The Top 5 Things to winterize your home

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Worse than useless air filter

Freezing temperatures are setting in around much of the country, so now what do you do? While each house is unique, there are some things to remember to avoid unpleasant surprises and expensive repairs later one.

#1: Winterize your outdoor water pipes

We all know, when pipes freeze, they often burst due to the extreme pressures exerted by the ice as it forms. If you have hoses outside, disconnect them from the faucet, drain the water that might be trapped in them, and store them for the winter.

If you have a pool or pond that needs winterization, make sure all exposed plumbing is drained. Some systems need to be filled with anti-freeze. Remember, any exposed pipes and even buried pipes, are likely to burst if there’s water in them over the winter.

Most homes have outdoor faucets for hoses. Modern faucets are “no-freeze” design, because they put the valve inside the house where the freeze hazard is lower. However, there are still millions of homes with older fixtures that get destroyed if not drained during the winter. Check your faucets for a shut-off valve inside the house and ensure that they’re drained properly.

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Ted’s Top Tips to Help You Beat the Heat!

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Record temperatures are creating uncomfortable conditions all over. Here in Pennsylvania, we’re expecting near 100F temperatures for much of this week, while Chicago just suffered through a heat index of 115F!

Along with high temperatures come big utility bills because of all the air conditioner usage. In this post, I’ll give you some tips for how you can “beat the heat” without breaking the bank!

Why Things Get Hot

If you’ve read any of my posts, you know that I like explaining things because I want you to understand WHY things occur. Once you know why, you can figure out solutions yourself.

Why do we use umbrellas to block the Sun? We all know that it’s cooler in the shade because the sun radiates heat. So if you can block the solar radiation, you can block a lot of the heat that it brings.

Even if you’re in the shade, it can get darned hot! If you’re sitting in your house, you’re being shaded by the roof – no direct sun is hitting you yet you’re still hot. Why? Because there’s still a lot of heat coming in – from the hot roof, the walls, sun shining through the windows and hot air entering the house.

There are other things that heat your house in the summer. Some obvious, some unexpected. You probably know that conventional light bulbs put out a lot of heat. In fact, each light bulb acts like a little space heater. But did you know that every appliance in your home, from your television to your refrigerator, is also pumping heat into the house 24-hours a day? And your water heater, especially if you have an oil boiler for your hot water – those throw off a ton of heat!

Quick recap -houses get hot in the summer because:

  • Solar radiation heats objects in direct sunlight, like your roof
  • Hot air carries heat directly into your house
  • Hot air and solar radiation heat your walls
  • Solar radiation enters through windows and skylights
  • Appliances and lights produce waste heat that enters your home

Beat the Heat!

Now that you know what causes your house to get hot, let’s see what you can do about it. I’ll start with the easy ones and work up to ideas that require more changes or greater investments.

  1. Wear light clothes. Ok, this one is so obvious that I’m embarrassed to write it! But simple things like shorts, a lightweight shirt and no socks make a big difference to your comfort level.
  2. Drink ice water or other no-calorie drinks. Cold drinks help reduce your body core temperature, that’s good. But don’t drink beer or soda or eat ice-cream and expect to stay cold. Anything with calories adds energy to your body, and that energy makes you less comfortable in hot weather.
  3. Use fans to circulate air around you, but only when you’re in the room. Fans cool you by speeding the evaporation of sweat and by carrying heat away from your body. But when you leave the room, turn off the fans or you’ll be wasting electricity AND adding heat to the air because the fan motor gets hot. Remember – fans do not cool the air!
  4. Turn up the temperature on your air conditioner. A slight increase in the temperature setting of your AC results in a significant reduction in the amount it runs. For example, raising the setting from 72 to 76 can reduce the energy use by 25%. Use a fan and turn up the temperature and you’ll see the savings on your next utility bill.
  5. Raise the temperature on your AC when you’re not at home. There’s a lot of debate on this one, but let me put it to rest – you save considerable energy by turning up your AC when you’re not at home. Yes, you have to crank the AC when you get home, but there is definitely a savings – you will save much more energy doing this than leaving the AC at a constant temperature all the time.
  6. Open the windows at night only if it’s cool and dry. Natural cooling at night is a great way to cool the house only when the air is dry. A big use of air conditioning is to remove moisture from the air so if you open your windows at night or in the morning when it’s really humid out, you’re filling your home with water. After that, your air conditioner has to work overtime to remove that moisture. So resist the temptation to open up the house when the humidity is high.
  7. Turn off lights when you’re not in the room. This is always good advice, but it makes even more sense when it’s hot out. Remember, those lights are little space heaters. The longer they burn, the more your air conditioner has to run to remove the heat that the lights put out.
  8. Replace lights with high-efficiency bulbs. This requires a little investment but it pays off year round. Compact fluorescent and LED bulbs are much more efficient than conventional bulbs mostly because they convert more of the electricity into light. I’ve written more than enough about the direct energy savings from these bulbs. Stop making excuses and replace those bulbs!
  9. Install a new fridge. And recycle your old refrigerator. The old energy hogs throw off an amazing amount of heat. A new, super-efficient fridge can pay for itself in a few years and it will heat your house less.
  10. Add insulation to your attic. If you don’t have at least a foot of insulation in your attic, you’re probably under-insulated. If you have a house from before the 1980’s, chances are, you only have a few inches of insulation. Going from 3 inches to the recommended 14″ of insulation (maybe R-9 to R-42) will reduce the amount of heat moving from your attic into your home by about 80%. A good insulation job is something you’ll appreciate year round.
  11. Shade your windows. Remember, a big reason things get hot is because of sunlight. Ideally, you don’t want direct sunlight entering the windows. The best way is by using trees or bushes to shade the windows. If that’s not possible, exterior awnings do a great job, though many people object to the aesthetics. If that’s you, then get interior cellular shades to block the direct light.
  12. Get windows with heat reflective coatings.  In recent years, window coatings have gotten truly amazing. A good window can block 90% of the heat from entering from the sunlight. This also protects your carpets from damaging UV radiation. An added benefit is that these same windows will hold in more heat during the winter and they’ll be less drafty. So replacing old, leaky, single-glazed windows with tight, low-e, double or triple-glazed windows can make a big difference in your comfort year round.
  13. Install a white-roof. Depending on your climate and your current insulation, this may or may not make sense. If you have lots of insulation, than the amount of heat coming in from your roof can make very little difference. But if you’re changing your roof anyway, get a reflective roof. This can substantially reduce attic temperatures and therefore the heat entering your home.
  14. Install a more efficient air conditioner. New air conditioning is usually my last recommendation. You’ll spend thousands of dollars and depending on where you live, you’ll may only use it a few months per year. However, if you have an old unit, it’s probably operating at less than SEER 10, so switching to a new SEER 18 unit can cut your AC bills nearly in half.

Preparing your home and air conditioner for summer

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Summer has arrived and you’ve probably already used your air conditioner. But how do you know it’s working at maximum efficiency?

Unfortunately, it’s not easy to tell if your AC is running at full spec. Even many professionals have difficulty squeezing out every last percent of efficiency, but you can certainly figure out whether there are big problems with your system.

  • Start with the easy stuff and replace the air filter(s) if they’re not really clean. The more restriction to the air flow, the less efficiently the system will operate.
  • Make sure you have an air tight cover on your filter port if the filter is one of the types that slide into your air handler’s housing. Why? If your air handler is in the attic and you leave that open, you can be losing 30% or more of your efficiency because of all the hot air that it sucks in through that opening.

Evaluating your cooling system performance

Next, run your air conditioner for a while, at least 20 minutes, so that it’s good and cold. Turn your thermostat down to 60F so that it will run continuously. You’re going to run some simple tests to see how the system is performing.
You’ll want to purchase an inexpensive air-speed and temperature gauge like this one. It’s well worth the investment as it lets you do basic troubleshooting on your system and can save you hundreds of dollars in diagnostic charges.
  • Measure the air speed and temperature at each of the vents, placing the unit right on the air register. The main thing is to be consistent in placement. Let it measure until the temperature stabilizes.
  • Also measure the air temperature going into your system. If you have a central air return, this is easy. You just need a general measurement of temperature. Usually this will be around 75F.
  • For each air output, with a typical system, you should measure the temperature of the cool air at about 20 degrees cooler than the air going into the system. That’s called the “temperature drop.” This number varies a fair amount, but if it’s less than 15F or greater than 25F, you probably have a problem with the system.
  • Get a feel for the amount of air coming out of each of the register. It should be a pretty good flow. If you find any that are much less flow than others, make a note of that. That could mean that a duct is detached or it might be shut off with a damper.
  • It’s also a good idea to note any rooms that don’t seem to be getting cool. There are a number of things that could cause this – insufficient cold air flow, poor insulation, solar heating through windows, hot air leaking into the room and so on. Try to determine the cause and make a note of this. For example, if the room isn’t on the sunny side of the house and the cool air flow seems good, you’ve probably have bad insulation or a big leak of hot air from the attic.
Making lists of the various symptoms you have is a good way to track down the big issues that are wasting your cooling dollars.

Check for hidden duct leaks

If you’re lucky, you can check your house for hidden duct leaks. It’s pretty simple.

  • Make sure all the windows and doors are closed tight and latched.
  • Check fireplace dampers to ensure that they are closed too.
  • Turn on all the bath fans, if you have any
  • Turn on the kitchen or range fan if it vents to the outside. If you’re lucky enough to have a Jenn-air range with blower, you’ve got access to a really great blower that’s perfect for this test!
  • Turn OFF the air conditioner and its fan. It may take several minutes for the blower to turn off.
The goal here is to be blowing air out of the house and create a negative pressure inside the house, meaning the house wants to suck air in through any leaks to the outside.
Now, you look for leaks!
  •  Just as you did before, check all the air conditioner vents. Since the AC is turned off, there should be no air coming out of them.
  • If there is any air coming in the vent, it means the duct system is leaking air to the outside.
  • Often, upstairs ductwork runs through the attic, and any air leaks there will pull very hot attic air into the house. These will be the easiest to find.
  • Make note of any vents that seem to be blowing hot air. The more air that comes in the vent, the closer the vent is to the leak.
  • If you find a particularly leaky vent, you might want to remove the vent and look in. I have found many that aren’t connected to the ceiling so you can see right into the attic! Or, the duct might have fallen off. A little detective work can go a long way.

What about the main unit?

So far, we’ve done things that you can do yourself to track down problems. But some things need to be done by a pro.

In general, if the system is delivering sufficient air to all the rooms and it’s about 20 degrees cooler than the air in the house, you’re probably in good shape. It still wouldn’t hurt to have the system checked out yearly, but honestly, what you’ve done so far enough to find the significant issues.

If you do find that the system isn’t cooling the air properly and you’re sure the air flow is good, then you should probably get the system checked out. But beware! If you have an AC contractor come out and he (they’re almost always male) says he need to “top it up with a pound or two of freon”, send him packing! AC systems never have to be “topped off” – they are “closed systems” so they should never use up their refrigerant (i.e. freon). Worse, these hacks can cost you hundreds or thousands of dollars in unnecessary repairs because adding too much refrigerant will damage your compressor and cause your system to run inefficiently.

One of the signs of an over-charged system is insufficient cooling of the air. So, in fact, I trust a technician far more if he says that the system is over-charged. But really, the proper way to evaluate the system is by doing a set of measurements on the refrigerant pressures and temperatures. With proper tests, they should be able to tell if there’s a problem with the system and, if so, what it is.

If your system does actually have a leak, it has to be fixed. You should not just add refrigerant because that will leak out and, if the system loses too much, you could end up having to replace the compressor. So make sure they track down the leak and fix it properly! With the proper equipment, most leaks are very easy to find.

This should get you started with your summer preparation. Stay cool!

What’s the best way to insulate your attic? or How I learned to think like a child

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U.S. EPA Air infiltration poster

Many of my posts come back to air sealing and insulating the attic. Why is that?

If you’ve done any searching about home weatherization, insulation, energy efficiency or related topics, you’ve probably come across the picture shown above. And for good reason – it clearly shows all the common sources of air leaking into (infiltration) and out of (exfiltration) your home.

One subtle part of the picture is that the size of the arrows represents the relative amounts of air leakage from each location. See all those big orange arrows going up into the attic? Those tell you that large amounts of warm air from your house leak into the attic during the winter. This is why all us energy geeks keep spouting about the importance of sealing up the attic before you waste you time on things like replacement windows, sealing electrical outlets, and so on. You can spend thousands of dollars and countless weekends working on all these other areas and it probably won’t improve your home’s energy efficiency as much as just focusing on your attic.

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