Archive for February, 2011

Bright Ideas for Saving Energy #2 – Check your Ducts

Posted: February 28, 2011 in Building Science, Conservation, Energy auditing, HVAC
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If you have any ducts in your home for heating or air conditioning, you might be losing a huge amount of energy. The good thing is, many of these problems are very easily solved if you’re not afraid to get a little dirty. How does five minutes and a roll of tape sound for a 30% energy efficiency improvement sound?

Attic Mounted Air Handlers

If the main blower (called an ‘air handler’) of your system is mounted in the attic, there’s a really good chance that you’re losing a significant amount of your system’s efficiency due to air leaks.

The air handler distributes air throughout the house. If you look up in the attic, you’ll see a variety of ducts going to and from the air handler. Every connection is suspect, but the worst problems are usually due to leaks where the air handler sucks air in.  This is called the “return” side of the system because the air is returning back to the system from the house.

Why are return air leaks so bad?

Think about the air in an attic. It’s dusty and usually filled with fiberglass particles. It’s also super hot in the summer and cold in the winter. The humidity in the attic usually matches the outdoor humidity, so that it’s very dry in the winter and damp in the summer. Any time there’s a leak on the return side of the system, that nasty attic air is getting sucked in and distributed around the house. Not only is this a serious efficiency problem, it can have health consequences.

How bad are return air leaks?

Consider a typical winter night when the heating system runs. It might be 30 degrees F in your attic. When the system sucks that air in, it has to raise it up to 100+ degrees to heat your home. This is as compared to heating up the 70 degree air in your house. This temperature difference multiplies how hard the system has to work. It is typical for the system to have to use two to four times as much energy to heat the air from the attic as the air from the house. That means a 10% leak gets multiplied to a 20%-40% decrease in your system’s efficiency!

During the summer, the same thing occurs, except now the system is sucking 130+ degree air in and trying to lower it to 50F for air conditioning. Now things get really bad! Your air conditioner cannot reduce the temperature of the air that much, so the system does a much worse job at air conditioning. Plus, it’s pulling all the humidity in, which makes the system work even harder. The net result is that your air conditioner can be almost worthless, or worse than worthless because it will be pulling in so much hot and humid air.

How do I know I have duct leaks?

There are a few telltale signs of return air leaks:

  • Very dusty house – if you clean often and yet you find the house gets dusty fast, you probably have a serious leak.
  • Very dry air in the winter
  • Very humid air in the summer, in spite of air conditioning
  • You feel drafts from the air registers when the system isn’t running
  • Your air filter gets dirty quickly
  • You can see the leaks

Where do I look for leaks?

The first thing to do is look at your air handler. The most common problem is when there’s no cover over the filter slot. This problem will easily decrease the efficiency of your system by 30%. In addition, you’ll find that the filter clogs up very quickly, like this one that is completely covered in dirt.

The next place to look is around the ducts near the filter. You can use a smoking incense stick and watch the smoke as you move it around the air handler while the system runs. If there’s a leak, the smoke will suck in, leading you right to the source of the leak! You can also purchase a cheap smoke gun, which works like a fog machine.

Another common place for leaks is where the ducts attach to the ceiling. They’ll usually be connected to the ceiling via a sheet metal box called a “duct boot.” Follow the ducts to each boot. Before you touch anything to look at the boot, take a look at the insulation around it. If it looks dirty or discolored, that’s a sure sign of a leak. It might be a duct leak or a leak from the house into the attic. In either case, you want to find the problem and seal it up.

It’s beyond this post to go into all the details about proper duct retrofits, but at least you can find them and know why you need to fix the leaks. One hint though – never use “duct tape” for sealing ducts. It’s not named right. It will always fail.

How do you know if your air handler is leaking into the attic?

Sometimes it’s really obvious. Sights like this may me cringe.

Leaks from the air handler into the attic can be pretty obvious during the winter. If you see a lot of snow melting off your roof, usually there’s a duct leak below it in the attic. So the first thing you should do is look at the outside of your house if there’s snow on the roof. There’s another post all about this that will help you find those problems.

The easiest thing to do is check where all the ducts connect to the air handler and the main trunk line (the big duct that comes off of the air handler, to which all the other ducts are attached). Make sure that all the ducts are tightly attached and air-tight. Each duct that is lose could be responsible for a 5%-10% decrease in your system efficiency.

This should be enough to get you started. For minimal investment in time and supplies, you can often improve your system’s energy efficiency by more than you could by purchasing a new, high-efficiency system. Even if you did buy a new system, if you don’t fix these problems, it will still work more poorly than an average system with excellent ducts.

The general rule is – if it looks wrong, it probably is!

-Happy hunting

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5 Bright Ideas for Saving Energy – #1 – Know thy use

Posted: February 27, 2011 in Conservation, Energy auditing
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When I give talks or do energy audits, people want to know the “best” ideas for saving energy. You know – the things that cut your energy bills in half and don’t cost much to implement.

Interestingly, this isn’t as crazy as it sounds. I’ve based my career on trying to give out as much practical information as possible. The theory is, if it’s easy and you can afford to do it, you’re much more likely to actually improve your home. This is as opposed to the idealist’s approach which promotes only doing things if you’re going to do them perfectly.

Without boring your further, let’s dive into five things that you can do to save energy in a meaningful way.

1: Know how to read your utility bill

By far the most important step to take is to learn how you and your home are using energy. This lets you prioritize your energy saving measures in a way that is most meaningful. I’ve seen people spend weeks caulking ares of their home that make absolutely no difference while leaving huge problems untouched.

I always recommend getting an energy audit as a starting point. However, the purpose of this article is not to get you to buy energy audits, it’s to teach you how you can do things yourself, so I’m going to skip that method.

The first thing is to look at your own utility bill. I can show you spreadsheets showing how other homes act, but there’s nothing like looking at your own utility bill.

Almost every electric bill has a graph like this one, showing a year or 13 months of usage data.

The vertical axis shows how much energy is used each month. In this case, it’s scaled from 0 to 2700 kilo-watt hours, or kWh.

Definition: a kWh is the amount of energy used by ten, 100 watt light bulbs in one hour.  This is the same as one, 1000 watt heating pad. If it adds up to 1000 watts and it runs for one hour, it uses 1 kWh per hour.

I hope that’s clear, because everything about electricity consumption depends upon you understanding what a kWh is.

On the horizontal axis is months. In this case, it runs from September of 2008 to September of 2009. This lets you compare this year’s bill for September with last year’s bill. This is very handy since it shows you at a glance if anything has changed dramatically since last year.

What does this graph tell us?

Look at the pattern of usage. The graph shows similar electrical consumption during September, October, May, June and August. Each of these has a total usage of about 450 kWh for the month or about 15 kWh per day. I’d include July, but that actually shows a bit less consumption. Maybe the homeowner went on vacation for a week in July?

What do these months have in common? The answer is – you don’t heat your house in these months. Now, look at the heating months. (Side note: this is from a home in Eastern Pennsylvania. This is a very typical heating consumption curve.)

The graph shows electric usage increasing in November, December, peaking in January, then dropping in February, March, and April. This makes sense too since January is consistently cold, so you’d expect the most usage when it’s cold. So everything makes sense.

Take a step back. What does this graph say about the house? It says that the occupant is using electric heating in an amount that is related to the outdoor temperature.

I’ll tell you a secret – this house is heated with oil, so somehow, the owner was paying a double heating bill, once for electric and once for oil. So just looking at the electric bill tells me that there’s something very wrong with this home. After all, if the home is heated with oil, why are they paying for an extra 2,000 kWh in January? That’s $320 in added electric costs (in this area). Over the course of the entire winter, they’re using 5,200 kWh, or about $830!

Winter usage spikes usually means electric heating

We’re learning an awful lot by looking at one part of an electric bill. Without even looking at the house, you know that there’s something happening here that’s dramatically increasing their electric bills in the winter. Common sense shows us that the usage corresponds to winter temperatures so it’s extremely likely that they’re using electric space heaters somewhere in their home.

It’s also telling us that they don’t use air conditioning during the summer. If they did, the graph would jump up during July and August, which can be pretty hot and humid in these parts.

Baseline electrical usage

Go back to our earlier observation that most of the non-heating months show an electric consumption of 450 kWh per month. The average usage during the low-usage months corresponds to the baseline electrical usage. This is the amount used for things excluding seasonal loads like heating and air conditioning.

For most homes, the baseline electrical usage includes electricity used for televisions/electronics, electric lighting, clothes washers/dryers, computers, dishwashers, electric water heaters, etc. – things you use all year long.

In this particular case, they use 450 kWh per month, or 15 kWh per day. This is comparatively low. Most homes I measure have 25-50 kWh per day consumption as the baseline, so the graph also tells us that there is nothing that is excessively sucking down electricity in the home during the non-heating months.

Getting More Specific

We’ve spent a lot of time looking at the broad usage patterns. What about specific consumption? Suppose we saw something that caught our eye on the graph, like high baseline usage? What then?

Recall in the definition of kWh I wrote: “a kWh is the amount of energy used by ten, 100 watt light bulbs in one hour.” I defined it that way because it frames an abstract term “kilowatt-hour” in a way that anybody can wrap their brain around. Ten 100 watt lightbulbs burning for one hour. Easy!

So, a home that uses 15 kWh in a day is using as much as those ten lightbulbs would burn during the waking hours. That’s not bad considering it includes all the washing, drying, dishes, television, etc.

On the other hand, if you found that the home had a baseline of 45 kWh, that would be like 30 bulbs burning all day – ouch! In fact, when I see a high baseline electrical usage, one of the first things that I’ll do will be to walk around the house, basically counting lightbulbs.

Obvious Problems

Quite often, these homes will be newer ones filled with recessed lights in the kitchen, living and family rooms. I’ll point at the kitchen ceiling, filled with 15 brightly burning flood lights and ask – “how long are these on during a typical day?” The answer is usually “oh, we keep those on from the time we wake up until we all go to sleep.”

At this point, my face will usually show disapproval (I’m really bad at hiding my emotions!) and I will say something like “do you know that those 15 lights, each 90 watts, are consuming about 20 kWh per day? That’s more than the ENTIRE household consumption of many homes?”

Anyway, I digress. The point should be well taken. Sometimes, the cause of your high consumption is blindingly obvious!

Not-so Obvious Problems

That was an easy (but very common) problem. What about the harder ones?

Well, sometimes, you just have to measure things, using a kill-a-watt meter like the one shown at the top of this post. This is a simple to use electric meter that any homeowner can use to measure the load of things that you plug in. For example, if you want to learn how much electricity that old fridge in the garage is using, just plug it in for a day and you’ll get a very accurate measurement.

Side note: occasionally, I’ll post links like this to items in the Ted’s Tips Amazon store. I’ve put together this store to hold all the items that I refer to on this blog so that you’ll be able to find them in one convenient place. Originally, I was linking to a lot of different sites, but then people would ask me where they could purchase them. Since I’ve been an Amazon user for years and know them to be extremely reliable and have low costs, I figured it was easiest to go this route. Anything you purchase there helps support this site. Thanks!

Back to measurements…

What Things Should You Measure?

You could spend months measuring everything in your house, but I’ll tell you where to start. These are the biggies. The proverbial “energy hogs.”

  • Refrigerators, especially old ones or those in garages during the summer
  • Dehumidifiers, especially those in damp basements or crawlspaces
  • Space heaters
  • Frequently used Halogen lamps
  • Anything with a heater in it that gets used a lot
  • Entertainment centers (especially large screen TV’s)
  • Large stereo amplifiers that get used many hours a day
  • Large gaming computer rigs

You should also make note of the following light fixtures. Keep track of the wattage of the bulbs and the length of time they burn each day.

  • Outdoor lights, especially bright flood-lights
  • Common area lights that are on most of the time (kitchen, living/family room, hallways)

I’m going to stop here for the day. This is more than enough to get you started doing your own home electrical consumption audit. If you follow these suggestions, learn how to read your utility bills and figure out how much energy you’re using, you’re well on your way to lowering your electric bill, maybe substantially. So get cracking – the watts are-a-wasting.

Energy Costs

Posted: February 26, 2011 in Building Science, Conservation, Energy auditing, HVAC
Tags: , , , ,

Sorry, I couldn’t come up with a snappy title for this one. This is about money and energy, so it’s a bit dry.

After my recent post on water heating, a friend dropped me a note and reminded me that the economics vary considerably depending upon the cost of the fuel. This is absolutely true, though unless you’ve studied a lot of utility bills, you might not realize just how much energy costs can vary.

Generally speaking, we have four energy sources that are widely available:

  • Natural gas
  • Propane
  • Heating oil
  • Electricity

Depending on where you live, the cost of each can vary widely. To complicate matters further, the price varies throughout the year, usually in proportion to the demand. So, for example, heating oil cost is the greatest in the dead of winter when you need it the most.

For the rest of this post, unless I note otherwise, I’ll be comparing fuels based upon their normalized cost. That is, I’ll be comparing the cost based upon the same amount of useful energy contained in the fuel. This can get confusing because most people refer to cost per gallon, but that’s meaningless because a gallon of liquid propane contains far less energy than a gallon of heating oil and you can’t even buy a gallon of natural gas or electricity.

Instead, we’ll be comparing fuels based upon their cost per million BTUs (also called MMBtu). What’s a million BTUs? It’s:

  • 7.25 gallons of heating oil
  • 10 CCF (or therms) of natural gas
  • 10.92 gallons of liquid propane
  • 292.91 kilowatt-hours of electricity

You can think of it as about the energy contained in half a tank of gas.

So the million dollar question is, how do fuels compare based on an equivalent amount of energy that they’re capable of producing?

To answer this, we have to look at a range of prices. For example, on the West coast and in the Northeast, fuel costs are quite high. Electricity in most areas is $0.15-$0.20 per kilowatt hour (KWh). That means the cost per MMBtu of electricity ranges from $43.94 to $58.58. But in some areas, or under certain rate plans, electricity is as low as $0.07 per KWh so the cost per MMBtu drops to $20.50.

So you see, this really complicates cost comparisons. That’s a three times range of cost. And it only gets more complicated when you compare multiple fuels! To simplify matters, here’s a table with each fuel, a range of costs, and then the corresponding range of costs per million BTUs.

Now the picture is getting a little clearer. You have natural gas at a low cost of $7 per MMBtu up to Electricity at almost $59 per MMBtu. That’s quite a range for the same amount of energy!

Let’s make this even more interesting! Instead of an abstract term like MMBtu, let’s convert this to “1,000 gallons of hot water”. I have to make a few assumptions here because this new calculation depends upon the starting and ending temperature of the water. For this, I’m basing the calculations on 50 degree water coming in and 130 degree hot water.

Heating 1,000 gallons of water takes 666,400 BTUs of energy. So if you were able to capture 100% of the energy contained in each of the fuels above and transfer it to the water for heating, you’d get the following:

What does the fuel really cost?

Notice that in all this discussion, I’ve kept things simple by just talking about the energy contained in the fuel. That assumes 100% efficiency. Unfortunately, nothing happens with 100% efficiency so we now have to complicate matters further by considering the actual efficiency of each system.

For these calculations, I’m going to use the typical efficiencies achieved in most households. You have to build your own spreadsheet if you want it to be accurate for your own situation.

Water heaters and their corresponding efficiencies

Water heaters are rated by their “energy factor.” This is a rating based upon the combustion efficiency and the heat loss of the storage tank, all measured under “typical conditions” whatever that means. The energy factor is a number from 0.0 to 1.0 representing 0% efficient to 100% efficient. I don’t know why they didn’t just use % efficiency, but they didn’t, so just remember an EF of 1.0 is perfect.

Natural gas, propane or standalone oil water heaters have an EF of about 0.59. Yes, you read that right – your conventional, combustion type water heater is only 59% efficient, if you’re lucky.

An electric storage tank water heater has an EF of about 0.90, or 90% efficient.

There are other technologies and types of water heaters, but in practice, these numbers apply to the vast majority of the homes in the U.S.

This tells us that the actual cost to heat your water is considerably different than what I showed in the tables above because the efficiency changes things, making electric water heaters much more appealing if you have cheap electricity.

Just for completeness, I’ll convert the table above to include these efficiencies. So the following table represents the cost to heat 1,000 gallons of water in a real water heater.

This final table represents the price range that a consumer would expect to pay to heat 1,000 gallons of water based upon typical water heater efficiencies and the range of fuel costs across the United States.

It has been a long journey, but if you followed it, you should now be able to figure out how much it’s really costing you to take a 20 minute shower or wash clothes with that old washer.

Postscript

In another post, I’m going to describe how you can analyze your own utility bills to see how much fuel you’re actually using for hot water. All these numbers are great, but what’s really important is how much it’s costing you to heat your water based upon your actual consumption.

Question: What are your thoughts on solar heated water?

Posted: February 26, 2011 in Conservation, HVAC, Solar power, Water heating

Question: What are your thoughts on solar heated water?
Answer:

Solar water heaters are one of the most underutilized alternative energy systems in the U.S. What could be better than reducing your energy consumption using the sun? Many other countries have “got it” and you’ll see solar water heating systems on most roofs.

There are three problems with them – we charge too much ($7000-$10,000), there aren’t enough qualified installers and they require maintenance. But if sized and installed properly, most families could satisfy 75%-90% of their hot water needs using solar on any sunny day.

Here are some resources for further reading:

Build it Solar – Site for solar DIY’ers.

U.S. Dept. of Energy

Wikipedia – Extensive article on solar water heating

 

Water heating – trimming your bills

Posted: February 25, 2011 in Conservation, Energy auditing, Water heating
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If you haven’t yet read my first posting about water heaters, I highly recommend that you do so now. Without that foundation, you’re not going to get the most out of this article.

Invariably, this question comes up – “how do I reduce my water heating bill?”

Let’s break this down into a few parts. What affects your bill?

  1. The amount of hot water you use
  2. The efficiency of your water heater
  3. The cost of your fuel
  4. Other inefficiencies

I’m going to address these points one at a time, because each one is important to understand and all impact your energy bills.

Reducing your hot water use

This one is obvious. Reduce the amount of water you use and you directly cut your energy bills. But how can you cut back on hot water use? I’m assuming that you aren’t willing to change your lifestyle because most people aren’t. I mean seriously, if you’ve taken 20 minute showers your entire life, are you suddenly going to start taking 10 minute showers, even if you know it might save you $100/year? Probably not.

Top ways to reduce your hot water usage:

Shower heads

Showers are one of the biggest consumers of hot water. Consider an older 4 gallon per minute shower head. That’s 60 gallons of water or maybe 40 gallons of hot water for each 15 minute shower. Ouch! That’s going to cost a fortune. If you can reduce that to 2 gallons per minute (GPM), you cut that to 20 gallons of hot water without changing your lifestyle. So the first act I would take is replacing the shower head.

But before you rush out and buy new shower heads, you might want to measure the flow of your existing heads. Just turn on the shower and time how long it takes to fill a 5 gallon bucket then calculate the number of gallons per minute. Easy!

  • If you’re not already using a reduced flow shower head (1.5-2.5 gallons/minute) then invest in one. I’m not talking about the pathetic little ones they sell that couldn’t wash the soap off a bald man’s head. I’m talking about nice, designer shower heads, that are designed for efficiency. Things like this one. I’ve used one of these for years and love it. No, it’s not the most efficient one around, but it’s reasonably efficient and it actually works.
  • If you’ve got teenagers who take really long showers, then get one of the 1.5gpm shower heads. They don’t work quite as well, but if they’re taking hour long showers, they can deal with a little inconvenience! If you’re feeling generous, you might get this one or this one.

Laundry Machines

Usually, I don’t endorse getting rid of perfectly good appliances – in most cases, it’s just wasteful. But I make an exception for laundry machines. The new front loaders with high-speed spin-dry cycles are worth the investment on so many levels.

A typical, old style, top-loading washer requires filling the entire tub with water multiple times during the cycle, using up to something like 35 gallons of water. They’re incredibly wasteful! Add to that the fact that the clothes are still pretty wet after the spin dry and you’re paying a lot more to dry the clothes as well. Finally, those agitators are simply brutal on delicate clothes. In all respects, top loaders are simply destined for extinction.

The front loader cuts your hot water usage very substantially. If you want a detailed discussion of them, go to the Energy Star website. They do require a little different usage, and special soap, but that’s a small price to pay for $100-$200 savings per year in reduced water use. They’re truly awesome!

Wash Clothes in Cold Water

You’ve heard it before and I’m going to say it again – the most efficient usage of hot water is not using hot water at all.

With modern laundry detergents, you do not need to wash clothes in hot water, and the savings can be hundreds of gallons per week if you do a lot of loads of laundry. That adds up to huge reductions in your hot water use over the course of a year.

Ok, so maybe you’ll still use hot water for some things, like your kids white socks that they wear outside without shoes or their football uniforms. But for a typical person, hot water wash is a complete waste.

Whole House Humidifiers

Many homes are outfitted with whole-house humidifiers. These bolt on the side of your furnace and introduce water into the air stream to humidify your home during the winter.

Unfortunately, some lazy product designers decided it was a good idea to run hot water through these units to help humidify the air because the hot water will be more “steamy” and work better. So what do these idiots do? They design a machine that runs something like 6 gallons of hot water through the system every hour, even when they’re only using a tiny fraction of that to humidify the air. Why? Because hot water is much more prone to scaling problems, so they run the water to flush out the mineral buildup!

Over the course of a day, that humidifier can be doubling your hot water use, easily. So over the course of a winter of use, that’s adding hundreds of dollars to your utility bills. Horrible. Stupid. Wasteful. These things should be outlawed.

If you’ve got one of these units that runs on hot water, disable it, shoot it, rip it off, and throw it in the trash. If you must have a humidifier (I’ll cover this topic in another post) then get one that uses cold water and a misting system or a sponge-like element.

BTW – I wrote an entire post about central humidifiers and their evils.

Remember to Fix those Drips!

Remember – there’s no such thing as a small leak! Even a slow drip can be gallons per day which means hundreds of gallons per year. That’s dollars out of your pocket and wasted water for absolutely no reason.

If you have a leaky faucet, fix it. Any homeowner should be capable of turning off the water supply and replacing a washer or faucet components. They’ve made it pretty easy for most things. So don’t hesitate. Fix the drip!

Here’s a nice tutorial on the subject.

And if you don’t like to read, here’s a video.

< End of part 2 >

Ok, I’m stopping here for the day. These have been the biggies and I’ve given you enough information to save you hundreds on your water heating bills each year. Now get busy replacing shower heads, buying new washers and dismantling your whole-house humidifiers!

Energy Data – your path to enlightenment…

Posted: February 24, 2011 in Energy auditing

As I said in the post on water heater, I’m a numbers guy. But you probably have no idea just how much of a numbers geek I am….

A few years ago, I found Phil Malone’s amazingly cool website documenting his journey to energy efficiency building his own super-efficient home. You see, Phil is a kindred spirit, as are all the people on this page. We’ve all come to the conclusion that energy monitoring can be fun and enlightening. After all, if you don’t measure it, how do you know how much energy you’re actually using? It’s all just a bunch of theoretical mumbo-jumbo.

So with this post, I’m putting my own home’s data on-line for you to see. Isn’t that cool? It’s all my home’s energy use at a glance. From anywhere in the world, I can go to that web page and see if my ground source heat pump is running and how much energy it is using.

Using this data monitoring, I’ve been able to discover when things in my home are amiss. For example, this winter, my boiler broke down, and I was able to determine exactly when it happened and how fast my house cooled down. Why is this a big deal? Because if I wasn’t at home, I would have seen this before my pipes froze and my home was flooded. It could have saved me tens of thousands of dollars.

But on a daily level, it tells me where and how much energy I’m using. At a glance, I can see how much energy my ground source heat pump is using and how much heat it’s pumping out, which tells me if it needs servicing or if it “needs a rest” (I’ll tell you that story another time, right now my blood pressure is high enough…)

It also shows me just how much it’s costing me to have a hot tub, sitting outside in the cold, all winter long, wasting energy, just so once a month (maybe), we can sit in it and enjoy the view. This is a “luxury”, so why don’t I feel luxurious…

Plus, it shows me interesting things. If you’re observant, you’ll notice that the cold water side of my radiant floor heater is hot while the hot side is cold. What’s up with that? That’s actually intentional, because I disabled the circulator pump and am allowing the system to work passively (called thermosiphoning). This saves the energy use of the circulator, which can be substantial.

So if you’re technically inclined and really want to know what’s going on around your home, I can’t recommend Phil’s Web Energy Logger highly enough. It’s truly awesome.

Water heaters – efficiency, insulation, costs…oh my!

Posted: February 24, 2011 in Building Science, HVAC, Water heating

After my last try at this long post, I’m going to break this one down into a few parts. There’s lots of material here, so bear with me.

So recently a friend asked me about water heaters – how much energy do they use and is adding insulation a good idea. Let’s start with energy use…

Energy Consumption

Just how much energy does a water heater use? Is it as significant as people say?

In a word – “YES!” – water heaters are a major consumer of household energy.

No matter how you slice it, this is a numbers question, and I’m a numbers guy. So get out your spreadsheet and prepare to think about BTUs and Energy Factors!

Let’s pull out a famous pie chart showing a comparison of average energy use for different things around the house. I grabbed this from the Energy Star website because they should know, right?

Well, as it turns out, I don’t know what fantasy world they’re getting their numbers from, but by my numbers, water heaters are responsible for 20%-50% of your utility bills, and I’ll show you how.

Here’s the problem – the answer to this question depends upon whether you’re a single person, living alone, who only showers once a week in tepid water, or if your household is multi-generational, with grandparents, parents, and seven children making loads of laundry every day. The occupants are the biggest factor in hot water use, so let’s look at them and how they affect the equation.

Hot water use based on occupancy

On average, people use 25-50 gallons of hot water per day, per person, so right there, you have a wide range. Think about it for a moment…If you shower every day for 10 minutes, that’s 22 gallons of warm water per day. Wash your hands a couple times and you’re using another gallon or two. A load of laundry? 10-30 gallons, and so on.

I emphasized “warm” water because most of the calculations I see count every use of water as all-out hot water, which is stupid. Nobody just runs the water on full hot unless they have their water heater set to a very low temperature. So when you take a shower, you might use 2/3 hot, 1/3 cold water. A 10 minute shower with a 2.5 gallon per minute shower head is 25 gallons of water but about 17 gallons of hot water.

However, there are other complications. For example, every time you run the hot water, you’re filling up the pipes between your water heater and your spigot with hot water. When you turn it off, all the heat in that water is lost. So you might run the faucet for 30 seconds to get warm water in the first place, then use it for 30 seconds and turn it off. The heat in the water in the pipes is “lost”. Yes – lost.

Some would argue that the heat goes into heating your home. Yes, true enough, you capture that waste heat during the winter. But during the summer? Oh…now that waste heat, usually 130 degree hot water, means your air conditioner has to work harder. It’s not so simple, is it? So for my calculations, I say that’s lost energy.

These are all reasons why the spread of usage is so wide. But let’s be conservative and use 25 gallons of hot water per person per day. How much energy is that?

Not so fast. How many people are in your household? Is it just you or do you have a family? For this example, I’m going to talk about a typical family of four. You can just multiply or divide the numbers based upon your own household size.

As it turns out, if you run the numbers, and I have, you’ll find that using 100 gallons of hot water per day costs you between $50 and $100 per month depending on your fuel costs and a few other factors like the efficiency and temperature of your water heater. Without turning this into a thesis, let’s just say it costs $70/month for hot water.

Depending upon the season and energy costs, the total monthly utility costs for a family of four will be $200-$400. Much more if it’s the dead of winter with an old oil boiler, less if you have a state-of-the-art geothermal heat pump. But this gives you an idea. So, if you’re on the low end of this, then the water heater accounts for 35% of the utility costs. On the other hand, it might be 10%-15% during the winter. But that gives you an idea of the typical ranges.

What does this all mean?

When you cut through all the verbiage, you discover that hot water is a big deal. Typically it’s 20%-30% of your total utility costs when taken over a full year – maybe around $750. This means that you should look at water heating as a “high leverage” area for improving your home’s energy efficiency.

I’ll touch on how to reduce your water heating bills in the next installment.

Energy Efficiency 101 – What’s an energy audit?

Posted: February 24, 2011 in Energy auditing
Tags: ,

If you’ve ever looked into energy efficiency, you’ve probably heard about energy audits. But what is an energy audit? What does it involves? Why should you get one? How much does it cost?

I’ll try to touch on all these topics, and more, in this posting, but if there’s anything I miss, please ask a question at “Ask Ted” and I’ll be sure to answer!

What is an energy audit?

This is a tough question to answer. The problem is, if you ask a bunch of us this question, you’ll get lots of different answers. It’s part of the problem – it’s become a marketing phrase that people put in their ads so they can sell you windows, insulation and other services.

So I’ll give you  my definition of an energy audit.

A proper energy audit is a bottom to top analysis of your home, inside and out. It’s kind of like a general physical for your home. The goal is to find how well constructed your home is from an energy, health and comfort perspective. Is it properly insulated? Is there any sign of water intrusion? How well are the heating and cooling systems installed? Are there drafts? Are the electric bills in line with expectations? How about other heating fuels (gas, propane or oil)?

A complete energy audit will usually include a blower-door test and a detailed thermal imaging (also called infrared) scan. I say usually, because sometimes the conditions aren’t appropriate for these tests. For example, during the spring and fall, the temperatures are usually too moderate for useful thermal imaging.

If it sounds like a pretty comprehensive analysis – it is! It typically takes me a minimum of three hours to go through the process on a small home and most of the time it’s a four-plus hour process. And to do it right, it can be pretty unpleasant.

In order to do an energy audit properly, every room and space in and around the house has to be visually inspected. That includes crawling around in the attic spaces, if they’re accessible and the basement and crawlspaces. In fact, on my jobs, I’ll spend more time in the attic and basement than anywhere else in the house because those areas have the most impact on the overall performance of your home.

What’s NOT an energy audit?

A warning – there are a lot of unscrupulous contractors advertising energy audits for free or for a very low cost, like $99-$199. They do this because they’re trying to sell you something, usually windows, insulation or a new heating system. This is like going to the brake shop and asking them to tell you if you need new brakes for your car. Of course you do! If you don’t get new brakes, you and your family’s life will be in danger! Blah, blah, blah.

So if some guy (they’re almost always guys) with a green business card tries to sell you on a cheap energy audit, send them packing. There’s virtually no chance that they’re going to do a proper job or even have the equipment to do a proper job. And they certainly won’t have the training or background.

Here are some things to look for when you’re interviewing people/companies to do an energy audit:

  • How long have they been doing this type of work?
  • How many homes have they analyzed?
  • Is this their primary line of work?
  • What organizations are they part of?
  • Do they profit by selling the work they recommend?
  • Can they send you a real sample report they’ve done for someone else?
  • Can they provide a half dozen references?

I would be particularly sensitive to whether this is their primary line of work and whether they’re getting kickbacks for selling you other services, for obvious reasons.

Note that, on occasion, contractors did give me money for sending clients their way as a way of thanking me. But it wasn’t a formal arrangement – it’s not like I only sent work their way because they were paying me. I provided my clients with a list of several contractors whom I knew to do high quality work. You’ll have to play this one by ear. You’ll know pretty quickly whether you can trust your auditor.

Also, insist on getting a sample report from a real client. If they make noises about not being able to do so because of privacy, scratch them off your list. We’re not lawyers or doctors – who cares if somebody sees your energy audit report? How hard is it to remove someone’s name and address from a report? If they’re not willing to go that far to win your business, how hard are they going to work once you hire them?

Question: Hi Ted, I was wondering about the energy used in heating hot water. I have heard it is bo

Posted: February 23, 2011 in Uncategorized

Question: Hi Ted,
I was wondering about the energy used in heating hot water. I have heard it is bout 20% of my utilities. I have also heard that by insulating it with 6 inch fiberglass will help to improve efficiency. What do you think?
Answer:

Ugh, I wrote a really long article in response and tumblr seems to have eaten it. 

I’ll try again after I get over the annoyance of losing this great post!

For now, start with the article on water heaters I wrote for my website.

Here’s part one of my answer as a full post.

Retrofit your attic hatch for improved comfort and energy efficiency

Posted: February 22, 2011 in Conservation, Construction techniques, Insulation
Tags: , ,

Link: Retrofit your attic hatch for improved comfort and energy efficiency

Thermal image of leaky attic hatch

The typical attic hatch is drafty and improperly insulated. Fixing it can reduce the energy loss of a room by half. This afternoon project is simple and cost effective providing results you can enjoy year-round.

If you’re looking for the best commercial product on the market, check out the Energy Guardian attic hatch covers from ESS Energy Products. They’re by far the nicest product I’ve seen for this application.

 

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