Why your high efficiency systems aren’t working

Here’s one I hear ALL the time: “I just installed a new high efficiency (air conditioner, furnace, windows, etc.), but my energy bills are still high and we’re still having comfort issues. What’s going on?”

First, we can’t say enough good things about the Energy Star program and what a great job it’s done of educating consumers about the value of high efficiency systems and appliances. That’s been a huge step in the right direction.

BUT, the missing piece is, your systems don’t interact independently – from each other, or from the shell of the home itself. You almost need to picture your home as a living, breathing thing. It needs to take air in, and it needs to exchange air out; that air needs to circulate; and any deficiencies in one system or area will impact the whole thing.

The number one reason high efficiency heating and air conditioning systems don’t perform well is that there are typically leaks somewhere in the home. THE AVERAGE HOME HAS THE EQUIVALENT OF A BASKETBALL SIZED HOLE IN IT, when you add up all the typical air leaks. So, if we’re talking about a furnace or boiler, all that nice toasty air it worked to produce is escaping – which means you’re still chilly. And, the furnace is working longer and harder than it should – which means your bills are still high.

High efficiency systems are fantastic, but before you make the investment, you gotta find and seal those air leaks!

Categories: Uncategorized

Goodbye incandescent light bulbs!

With the new year comes some changes in energy legislation. First, some great news: 2012 starts the official phase-out of incandescent lightbulbs. The Energy Independence Act of 2007 created various efficiency standards, including the declaration for lightbulbs to be at least 25% more efficient in 5 years or they couldn’t be manufactured in the United States. Specifically, starting Jan. 1, 2012, traditional 100-watt incandescents would have to be more efficient or stop being manufactured. The same is stated for 75-watt bulbs by Jan. 1, 2013, and 60 and 40-watt bulbs by 2014. Manufacturers have since invested millions of dollars in more efficient lighting, including halogen, compact flourescent and light-emitting diodes (or LEDs), and will no longer produce traditional incandescent bulbs (Read our blog comparing CFLs and LEDs). You can still purchase incandescents though, and unfortunately reports say consumers will probably do so until they are forced to switch. However, it looks like we are on our way to being a more energy-efficient country!
There is some bad energy legislation news though: the federal tax credit for builders to build energy efficient homes and for homeowners to install energy efficient products expired on December 31, 2011. The energy industry is urging Congress to extend these residential tax credits, and you can help by speaking to your local representative! Extending these credits could give you money back on energy efficient upgrades like windows or Energy Star appliances for your home! You can CLICK HERE to see RESNET’s efforts to reinstate the credit, exactly what’s involved, and their guidance on how you can help.

3 Problems with Atmospheric Combustion Inside the Building Envelope

Atmospheric combustion appliances inside the building envelope can create health & safety problems.A lot of houses have atmospheric combustion appliances. What that means is that a lot of houses have the potential for serious health and safety problems, as well as higher energy bills.

First, let me define atmospheric combustion because, unless they’re in the HVAC business or have training in how to do a home energy audit, many people don’t know what it means. An atmospheric combustion appliance is one that draws air from the space around the appliance. You could, if you desired, pull the cover off and stick your finger into the blue flame. (Strangely, fewer people are drawn to do that than to stick their tongues on a frozen steel pole.)

The two atmospheric combustion appliances of most concern are furnaces and water heaters. (Fireplaces deserve their own article, so I’ll leave them for later.) If your atmospheric combustion furnace or water heater is in a vented crawl space or a vented attic, it’s outside the building envelope and is less likely to create health and safety problems inside the house. (Less likely but not impossible.)

Here’s the basic process for furnaces and water heaters:

  1. Pull in air to mix with the natural gas.
  2. Burn the mixture of gas and air.
  3. Exhaust the combustion gases to the outside through the flue.

I’ve left out the part about why we’re burning gas in the first place, which is to add heat to the home or the waterAtmospheric combustion appliances use room air, which can create negative pressure. in the water heater’s tank. Here, my only concern is the combustion process.

An atmospheric combustion furnace pulls room air into the combustion chamber through the grill on the front (photo right). A water heater pulls air in at the bottom near the pilot light.

Problem #1 – Negative pressure increases infiltration.

When the furnace or water heater or both are running, they’re pulling in room air and sending it to the outside. A basic rule of building science, and something that all home energy auditors learn, is that for every cubic foot of air that leaves the house, another cubic foot of air comes in. By running these atmospheric combustion appliances inside the conditioned space, you’re increasing the infiltration that the house experiences. Your energy bills will be higher as a result, and you may find the house a bit drafty while the furnace is running.

I’ve written in this space before that you can’t make a house too tight, but you have to pay attention to the combustion safety issues before you go air-sealing your home. You want it tight, but you don’t want to increase the probability for the next problem.

Problem #2 – Negative pressure can backdraft the water heater.

atmospheric combustion water heater health safety carbon monoxide flue gapSee that gap between the top of the water heater and the bottom of the flue? It’s designed to draw air in to aid the natural draft (stack effect) of the water heater. Warm air rises, so as a water heater runs and the warm combustion gases rise in the flue, the opening helps allowing more warm air from the room to rise.

The problem here is that that opening also allows air to come down the flue. If the air pressure in the room is low enough relative to the air pressure where the flue terminates outside, air will come down the flue. If air is coming down the flue while the water heater is firing, combustion gases will not go up the flue. They’re coming into the room.

This is where things get interesting. Under normal operating conditions, with the combustion gases exhausting up the flue, the combustion process results mainly in water vapor and carbon dioxide. When the water heater is backdrafting, the combustion process changes. The flame may get starved for oxygen, causing incomplete combustion, which results in significantly more carbon monoxide in the combustion gases.

Carbon monoxide, needless to say, is bad. You don’t want it in the air in your house, which is exactly where it goes if the water heater is backdrafting. It can’t go up the flue.

Problem #3 – Common venting of water heaters and furnaces overrides an important safety feature of furnaces.

At the base of the flue in an atmospheric combustion furnace is a draft inducer. It’s a little fan that pulls air up through the heat exchanger. Right next to that fan is a pressure sensor that will cut off the furnace if it detects that the pressure in the flue is too high. If a squirrel or a bird builds a nest at the top of the flue, and the combustion gases can’t escape, this sensor can save your life by shutting off the furnace.

atmospheric combustion furnace water heating common venting carbon monoxide draft inducer

When your water heater flue is connected to the furnace flue (see second photo above), however, that squirrel nest at the top of the flue still keeps the combustion gases from going out, but the sensor may not detect a high enough pressure to shut off the furnace. The reason is that the combustion gases now have another escape path – at the top of the water heater!

The Solutions

If you have atmospheric combustion inside the building envelope in your home, here are some options to eliminate or reduce the likelihood of problems:

  • Go with a sealed combustion furnace and direct vent, power-vented, or sealed combustion water heater if you still want to use gas inside the conditioned space.
  • Create a sealed combustion closet out of the room where the atmospheric combustion appliances are. To do this, you need to isolate the room completely by air-sealing between it and the rest of the house and then bringing in combustion air.
  • Convert from natural gas to electricity. We recently ran a two guest posts from David Butler advocating for this approach: Just Say No to Furnaces in High Performance Homes and Heat Pumps and Hydronics – A Great Team for High Performance Homes.

Combustion safety is a huge issue, and it’s a big part of looking at the house as a system, which takes us back to Building Science 101. It’s certainly possible to use natural gas safely in our homes, but we need to pay attention and do it the right way. Putting atmospheric combustion appliances inside the conditioned space is not the right way.

All one needs to do is to Google “CO Accidents” and we see first hand the dangers of atmospheric combustion appliances in living spaces with humans (and pets for that matter).  Here in the DFW area we recently had a family trying to keep warm by burning their charcoal grill inside the house. All present went to the hospital unconscious and the father of the family had 2 heart attacks on the way to the hospital triggered by CO poisoning. Obviously this is an extreme situation and not quite the same as what we’re talking about here, but the premise is the same. CO is bad. It kills. Slowly.

How about we all go all-electric and be safe?

Cold Interior Walls, Useless Insulation, and Building Science

It seems so simple. There’s outside, and there’s inside. The walls, ceilings, and floors that separate the cold outside from the warm inside should be the only surfaces that rob heat from your home. Interior walls have conditioned space on both sides, so they shouldn’t be a problem, right?

Wrong! I’ve seen and worked on several houses that lose heat through their interior walls. They’re usually older houses that have been modified from the original, but I’ve seen these problems in new houses, too.

In such houses, the problem results from the top of the walls being open to the attic. You can go into the attic and look down into the interior walls and see the drywall. That means that cold attic air gets down into those cavities.

With cold air inside the wall and warm air on each side in the house, heat moves through the drywall, which has a low R-value, and warms up the air in the cavity. The warm air then rises into the attic (a process called the stack effect). As that warmed air leaves the interior wall, cold attic air moves into the cavity to take its place, resulting in more heat loss. This process continues as long as the attic stays cold and the house is warm.

To fix the problem, you have to stop air from moving into or out of the interior wall cavities. One way to do this is to cover the opening with a rigid material and use caulk or spray foam to seal the edges.

Another way is to stuff a piece of fiberglass insulation into the gap at the top of the wall and spray foam over it. It’s important to note that the fiberglass by itself is not sufficient because fiberglass does not stop air movement. (That’s why it’s used in filters, duh!)

Another problem I see in attics is attic with two ceilings and insulation in the wrong place. A lot of old houses with high ceilings have had lower ceilings put in below the original ceiling. In that case, insulation on top of the original ceiling fails to keep the house warm. Again, it’s a matter of understanding where the attic air is going. These houses have two ceilings: the original ceiling and the current ceiling, which is lower.

The blown fiberglass insulation is almost always on top of the original ceiling because that’s the ceiling you see from the attic. In the course of modifying the houses, however, the workers opened many pathways for air to move from the attic to the space between the original ceiling and the current ceiling.

The result is that the air under the insulation (between the two ceilings) is at the same temperature as the attic air. That cold air is separated from the house only by a layer of drywall. As that air warms up from heat moving through the drywall, it moves through the openings into the attic and is replaced by more cold air. The insulation is useless because it’s in the wrong place!

If you want to understand politics, you often have to follow the money. If you want to understand heat loss in your home, you often have to follow the air.

Does Energy Efficiency Drive Home Builders out of Business?

A couple of months ago, I was reading a discussion in one of the many LinkedIn groups that I belong to and came across a comment arguing that energy efficiency requirements drive builders out of business. Here’s part of what this fellow wrote:

“No one is against saving water or being more energy efficient, in fact if you can build a better mouse trap then the competition you will win over the customer. The point that I have been making is that the goverment is mandating things that most consumers can’t afford to pay for which puts builders out of business. The more builders that go out of business the higher prices will go for the consumers.

“Most builders who adopt a green agenda are very sincere in their ambitions but soon find out that customers love what they are doing, but they can’t or are unwilling to pay for it. In many markets today you can’t make it work because of appraisals. Also, understand if you come up with ideas that produce a better mouse trap and you can sell it, I will be the first to stand up and cheer you on. I am just stating what I have seen from my 25 years in the business.”

This argument is gaining traction among some home builders because energy codes have stiffened their requirements. For example, in Georgia, the state passed a new energy code that (mostly) went into effect on 1 January of this year. Among the new requirements:

Infiltration test required on all new homes, which must be 7 ACH50 or less
Duct leakage test required on all new homes, with 8 cfm25 per 100 square feet of conditioned floor area served by the system
No power attic ventilators, unless they’re solar
No electric resistance heat used as primary heat source
At least 50% of the lighting must be ‘high-efficacy’ or have sensors or automation to shut it off when not in use

Will these new requirements cost builders extra? Mostly, yes. If they’ve been installing power attic ventilators, though, they’ll now save a little bit by not putting them in.

Sealing up the house and the ducts to limit the amount of leakage shouldn’t cost extra because they should be doing this already. Plus, the thresholds for passing are pretty easy to attain. Once builders and their trade contractors learn the details, it’ll be easy to do and add little to no cost.

Yes, there’ll be a cost to have their work tested, and I think when Mike Barcik surveyed HERS raters around the state last year, he found the average cost of a test would be around $75. Also, the new energy code doesn’t even require third party testing. Builders and HVAC contractors can get trained as Duct and Envelope Tightness (DET) Verifiers and test their own work.

Getting back to the main question, will the extra burden and cost of meeting the new requirements drive home builders out of business? Hmmmm.

Have disposal requirements put tire manufacturers out of business?
Did the new security procedures instituted after 9/11 bankrupt airlines?
Does a former drill sergeant make a terrible therapist? (Oh, wait, that’s a Geico commercial. Sorry.)

My answer is an emphatic No. Yes, builders have gone out of business and will continue to fold. The main factor in the past few years, though, is the economic downturn, not new energy efficiency requirements. Correlation does not imply causality. Just because home energy efficiency requirements have increased and builders have gone under doesn’t mean one caused the other.

Also, if we’re talking government mandates, as the commenter above referenced, then we have a level playing field. All builders have to do it, so home buyers don’t have the option of going to one who’s not incurring the extra cost to meet the requirements.

In my opinion, new requirements for home energy efficiency are essential. Building science has come a long way in the past few decades, and we know that conventional home-building methods lead to a host of problems – and that they’re easily remedied. We’re also grappling with serious energy security issues, and every little bit helps.

The argument that efficiency drives builders out of business is similar to the claim that requiring greater energy efficiency takes away our freedom. Basically, I think, it comes down to people in the construction industry being resistant to change. They want to do things they way they’ve always done them, but that’s a guaranteed path to going out of business.

What do you think? Does energy efficiency drive home builders out of business?

Categories: Uncategorized

Myth: Closing Vents Saves Energy

Thanks to Mark Cannella, Founder of ProEnergy Consultants for the following artice:

I’ve personally performed thousands of energy audits during my time, so I’ve seen some pretty interesting things people do in their well meaning attempts to save energy. Let me just say that duct tape is not a suitable material for any energy-related home improvement!

A very common activity that seems to make sense on the surface is closing the vents in low-use areas or rooms of the home. People think, ”this will prevent wasted money on heating/cooling this space.’ But this logic is wrong, and can wind up costing you.

First, when you close a vent, the air that was directed to it gets stuck. With nowhere to go, it applies backpressure on the unit’s fan, causing it to work harder (burn more energy) to do its job. Overtime, this will also cause the fan to wear out quicker.

Second, your HVAC unit will produce the same amount of conditioned air, regardless of how many vents are open/closed (so you are not reducing energy consumption). When you close a vent, you are simply sending more conditioned air into spaces that don’t need it – often times, this can even make other rooms UNcomfortable.

Lastly, restricting the flow of conditioned air increases the probability that it will be pushed out through the leaks in your duct work, decreasing your energy efficiency. (Now if you’ve followed our duct sealing project video on YouTube, this should be less of a concern for you!)

Bottom line, closing your vents can do way more harm than good.

Categories: Uncategorized

Changing Habits vs. Changing Homes

Residential buildings are responsible for using roughly 20 percent of the total energy consumed in the United States, according to the Environmental Protection Agency.

This presents a huge opportunity for home energy savings, and figuring out the best way to get homeowners to save energy is an important area of research.

A UK organization called BioRegional is looking at opportunities for home energy savings by monitoring the energy use in three homes. One home will be revamped with everything from insulation to solar panels to cut its energy use by 80 percent, another home will be upgraded with standard cost-effective retrofits, such as adding insulation and a boiler replacement, and the final home will not be changed. Meanwhile, the homeowners in all three homes will be coached on how to change their day-to-day behaviors to save energy.

Changing Habits vs. Changing Homes

While the results won’t be final until 2013, my money is on the second house. Both changing habits and changing homes play an important role in energy savings, and both have their limits, realistically and financially. Here are some ways that habitual changes can be paired with energy efficiency retrofits:

Lighting and Electronics

Installing energy efficient lighting and electronic power strips in your home is a great low-cost way to cut back your energy use, but to achieve the full savings potential of these appliances, it’s very import to change your habits as well. For example, if you plug all of your appliances into a power strip but then forget to switch the strip off when you’re not using your appliances, it’s not being used effectively. And of course, turning off a light when you’re not in the room may seem obvious, but some people still forget to flip the switch.

ENERGY STAR Appliances

Replacing outdated refrigerators, dishwashers, clothes washers, etc. with ENERGY STAR models can significantly lower your utility bills, but there are also tricks to maximizing your energy savings. For example, keeping your refrigerator and freezer well stocked, waiting to run the dishwasher until it’s full and washing your clothes with cold water are all ways to use your appliances more efficiently. You should also consider what time you’re operating these appliances because you will pay more to use them when power is at peak demand. (See Federal and State rebates for energy efficiency upgrades)

Heating and Cooling

There are a lot of energy efficiency upgrades that target heating and cooling costs, from adding insulation to repairing and air sealing ductwork, and there are behavioral changes that can be made in combination with these energy efficiency retrofits. While you should be comfortable in your home without wearing a snowsuit, it makes sense to dress for the season you’re in. Also, you can turn down the heat when your family is out of the house. One technological change that can assist with this behavioral change is a programmable thermostat. This allows you to pre-program a comfortable heating and cooling schedule, and you can set your home to heat back up just before you get home from work.

Your home and habits

A great way to figure out which energy efficiency upgrades and behavioral changes would make sense in your home is to start with an energy audit (ProEnergyConsultants.com).  The consultant will test your home and give you a prioritized list of recommendations on how you can make your home more efficient, and the consultant will also tell you which upgrades will be most cost effective.  Don’t rely on a contracting company, such as an insulation or window company for your energy audit.  They are NOT impartial auditors and don’t have your best interests in mind.  They’re there to sell you their product.  Make sure it’s an unbiased, independent 3rd party auditing company like Pro Energy Consultants (888-811-7773).

Save Energy.  Save Money.  Save the Environment.