2012 January 18 Wednesday
Light Wood Fires From On Top

The Norwegian Institute of Public Health says for healthier air light your wood burning heaters from the top, not the bottom. An added benefit: more complete burning means higher efficiency. You get more heat from the wood.

  • when the wood is lit from above, the heat radiates to warm the wood underneath. These pieces of wood will begin to emit gases which will rise, meet the flames and ignite
  • if you light from below, the heat radiation will cause the wood over the flames to release gases which will rise. Without flames at the top of the wood, the gases will be released unburnt out of the combustion chamber to the chimney, where they will form particles
  • the particle emissions from the chimney will be halved
  • you gain maximum heating efficiency from your wood and thus lower your heating costs

Before anyone states "this is obvious": I've seen wood fires lit from the bottom many times. It is usually seen as easier to light from the bottom. Kindling can light bigger logs above it.

But it makes sense that a fire on top can burn the gases that get released from warming wood underneath them. So try to light the top.

Update: "pond" points to instructions on how to easily light from the top. What's still missing: How to easily load new logs into a burning fire bottom-up?

By Randall Parker    2012 January 18 10:58 PM   Entry Permalink | Comments (13)
2010 September 28 Tuesday
Passivhaus High Home Efficiency Shows Up In America

A Prius is so 5 years ago as a way to signal your dedication to energy efficiency or the environment. The German Passivhaus extremely high efficiency home design standard represents a far bigger dedication to energy efficiency. It is so cool (er, warm) that I'm tempted to move somewhere cold to justify building one. The 106F temperature in my town on Monday makes that an even more appealing idea.

A so-called passive home like the one the Landaus are now building is so purposefully designed and built — from its orientation toward the sun and superthick insulation to its algorithmic design and virtually unbroken air envelope — that it requires minimal heating, even in chilly New England.

Why mess around with wimpy Energy Star and LEED design goals when you can step up to some serious techno-geek levels of efficiency?

Energy Star and LEED aim for efficiency improvements of at least 15 percent over conventional construction — and both programs can earn a variety of tax credits and other incentives. The passive-home standard, perhaps because it’s unfamiliar to many officials who create efficiency stimulus programs, is eligible for few direct government subsidies, despite the fact that homes using it can be up to 80 percent more energy-efficient, over all, than standard new houses and consume just 10 percent of the heating and cooling energy.

Want to have serious bragging rights? Build to the Passivhaus standard. Also, while the German Passivhaus institute has an American affiliate that uses English style spelling you can emphasize the sheer engineering geekiness of what you are doing by using the more chic German spelling.

But seriously, I am impressed that such a large improvement in home efficiency is possible at an affordable increment in cost (maybe 10% or 15% according to the article). Given where I expect oil and eventually natural gas prices to go the only other long term feasible option for heating in really cold areas is ground sink heat pumps. Electric power costs won't rise as much as first oil and later natural gas. So heat pump heating costs will stay low compared to oil and natural gas. But since the migration away from heating oil in the US is over two thirds complete I do not expect the coming rise in oil prices to provide a major impetus for PassivHaus.

The article neglected to mention one advantage of PassivHaus design: in the face of the spread of the Asian stink bug the extreme sealing characteristic of PassivHaus will keep out the bug invasion.

Mr. Jacobs, the urban entomologist, said the response to stink bugs so far is not an overreaction. “I’m standing here in my living room watching some of them crawl up my walls,” he said. “The best thing to do is make your house as tight as possible. Use masking tape to seal around sliding glass doors, air-conditioners.”

PassivHaus will protect you from foreign insects from other continents.

By Randall Parker    2010 September 28 08:31 PM   Entry Permalink | Comments (17)
2010 June 27 Sunday
Finnish Heat Exchanger Raises Heating Efficiency

Michael Kanellos of GreenTechMedia reports on The development of a small yet highly efficient technology for heat exchange and heat pumping which captures over 90% of waste heat expelled in a home's expelled stale air.

Heat pumps and heat recovery systems will then be able to drop power consumption to 435 watts, Luukkainen said, by pre-heating incoming air to 14 Celsius or more and ejecting air at -17 degrees. In other words, the incoming air only will only require 7 degrees of heating (21 degrees minus 14 degrees), and a good portion of that energy will come from heat absorbed from outgoing air that is 38 degrees cooler (21 degrees minus -17 degrees) than it would be without this sort of heat recovery system.

Luukkainen put one in his own house. When it was minus 28 degrees Celsius outside, the incoming air came in at 22 degrees. He ejected air at minus 22 degrees.

Combined with better insulation the company claims their technology will reduce the energy required to keep a house warm in winter by a full order of magnitude.

Electric powered heat pumps and heat exchangers fit well with Finland's larger energy strategy. The new Olkiluoto 3 nuclear reactor's construction is nearing completion and, in spite of that reactor going over $2 billion over budget, the Finnish government looks set to approve construction of 2 more nuclear reactors. The Finns are setting themselves up to depend less on Russian natural gas for heating and electric power generation.

Heat pumps and heat exchangers cost more up front. But since they can use electric power so efficiently they pay off in the long term in avoided higher costs for oil or natural gas. Buildings can be powered by a mix of nuclear, wind, and solar electric power. Transportation and the chemicals industry face a much tougher task in breaking away from fossil fuels dependency.

By Randall Parker    2010 June 27 05:46 PM   Entry Permalink | Comments (3)
2010 February 06 Saturday
Phase Change Material Could Cool Houses

MIT's Technology Review reports on paraffin wax capsules could use the cold of evening to cool rooms in the day.

Building materials that absorb heat during the day and release it at night, eliminating the need for air-conditioning in some climates, will soon be on the market in the United States. The North Carolina company National Gypsum is testing drywall sheets--the plaster panels that make up the walls in most new buildings--containing capsules that absorb heat to passively cool a building. The capsules, made by chemical giant BASF, can be incorporated into a range of construction materials and are already found in some products in Europe.

This won't help much so much where the difference in day and night temperatures is small. But desert areas get very cool at night. So this approach would work well for these areas. What I wonder: Does the paraffin increase the flammability of the walls in a fire?

One could also use a similar approach to make use of lower night rates for electricity. Run an air conditioner or ground sink heat pump at night and use it to cool a compound from liquid to solid phase at night. Then blow home air over the solid during the day to cool it.

Pricing of electricity by time of day and even by level of demand would provide more incentive to implement storage systems for heat and cool. Changes in utility regulatory policies to change electricity pricing based on supply and demand would encourage greater use of materials for storing cool and heat.

By Randall Parker    2010 February 06 08:03 PM   Entry Permalink | Comments (11)
2009 November 25 Wednesday
Deep Retrofits For Housing Efficiency

An Oak Ridge National Laboratory program to do deep retrofits of housing for energy efficiency comes up with an average $20k price tag. How can this pay itself back?

Deep energy retrofits are renovations to existing structures that use the latest in energy-efficient materials and technologies and result in significant energy reductions. Jeff Christian, the ORNL buildings technologies researcher heading the project, said at least 10 homes across the region will be sought to participate. The home selection process is yet to be finalized, and homeowners will have to pay most of the costs—about $10 per square foot of living space—and agree to allow their post-retrofit energy consumption to be monitored. But Christian said costs can be recovered in as little as 10 years, and energy bills potentially can be cut in half. Most important, data from the project can provide huge incentives for more deep retrofits across the region, he said.

So for a 2000 square foot house the total cost is $20,000. Any readers have a house about that big? How much are your yearly energy bills? I'm skeptical of a 10 year payback time for a retrofit that is so expensive. In fact, I went to a mortgage calculator, specified a 10 year, $20,000, 6% loan (too high or low?) and got a monthly payment rate of $222. Someone would to have a monthly average energy bill of $444 to cut in half with retrofits to pay it back in 10 years. Does anyone have an energy bill that large on a 2000 square foot house? Setting the payback time to 20 years the monthly payment comes out to $143. Got a monthly $286 average bill for electricity and natural gas or heating oil?

I wonder whether they include the solar panels mentioned below in this retrofit.

The retrofits are part of an energy-efficient systems approach that involves making the building more air-tight; weatherizing the attic, crawl space and windows; upgrading heating and cooling units, water heaters, appliances and lighting; and installing solar panels.

Oak Ridge is in Tennessee which can have some pretty hot summers. So they are looking for big savings from reworking how the house and attic get cooled. Got a big air conditioning bill?

Christian explained many new two-story houses have a heat pump for downstairs and another in the attic for upstairs. Much of the cost of cooling conventional houses comes from the unit in the hot attic operating very inefficiently. In a retrofit house, insulation is removed from the attic floor. The roof and sides of the attic are sealed with insulating foam, and a high-efficiency heat pump is installed in the attic. The result: huge energy savings in heating and cooling because the entire HVAC system is inside the insulation layer.

If you ever build a home from scratch then build it for high energy efficiency. Retrofitting is a lot more expensive.

Update: The 8 year payback time must be due to the subsidy paid by the taxpayers. As a few commenters point out, the rest of us pay for this. I'm with them in thinking this subsidy is a bad idea. Most of the energy savings can be had for a small portion of the total $20k cost. Think about that. Spend the same $20k over several houses and the total energy savings would be much larger.

If ORNL wanted to do something useful with taxpayers money about home energy efficiency they'd come up with methods everyone could use to analyse their house to determine what are the low hanging fruit.

By Randall Parker    2009 November 25 08:48 PM   Entry Permalink | Comments (28)
2008 December 27 Saturday
Residential Use Of Coal Up In United States

Bad news for the environment:

Burning coal at home was once commonplace, of course, but the practice had been declining for decades. Coal consumption for residential use hit a low of 258,000 tons in 2006 — then started to rise. It jumped 9 percent in 2007, according to the Energy Information Administration, and 10 percent more in the first eight months of 2008.

Online coal forums are buzzing with activity, as residential coal enthusiasts trade tips and advice for buying and tending to coal heaters. And manufacturers and dealers of coal-burning stoves say they have been deluged with orders — many placed when the price of heating oil jumped last summer — that they are struggling to fill.

In the United States wood burning stoves are more regulated than coal burning stoves for residential heating. That should change. Coal contains more toxins (e.g. mercury) than wood and so burning coal is worse than burning wood in residences. At least when coal is used in big electric power generation plants the expertise and capital are available to burn it very cleanly - if only the regulations were tough enough to require extremely clean coal burning for electric power generation.

Burning coal saves a lot of money for houses in colder areas. For people who are spending thousands of dollars per winter on heating oil the use of coal can cut out most of those costs.

Coals vary in quality, but on average, a ton of coal contains about as much potential heat as 146 gallons of heating oil or 20,000 cubic feet of natural gas, according to the Energy Information Administration. A ton of anthracite, a particularly high grade of coal, can cost as little as $120 near mines in Pennsylvania. The equivalent amount of heating oil would cost roughly $380, based on the most recent prices in the state — and over $470 using prices from December 2007. An equivalent amount of natural gas would cost about $480 at current prices.

Ground sink heat pumps, insulation upgrades, solar heating systems, and other cleaner alternatives are environmentally better than coal for heating. Anyone who is thinking about installing a coal heater ought to investigate alternatives. Coal is much less convenient. The need to empty out the ash on a daily basis and to shovel coal into feeders is also more laborious. Plus, coal requires constant residence in a house to prevent freezing up.

By Randall Parker    2008 December 27 11:36 PM   Entry Permalink | Comments (22)
Passive House Design Takes Off In Germany

The idea of extremely well insulated houses which need little heating is not a new one. But advances in design made at an institute in Darmstadt Germany are making so-called passive houses more practical. A New York Times article takes a look at the growing popularity of passive house designs for heating.

The concept of the passive house, pioneered in this city of 140,000 outside Frankfurt, approaches the challenge from a different angle. Using ultrathick insulation and complex doors and windows, the architect engineers a home encased in an airtight shell, so that barely any heat escapes and barely any cold seeps in. That means a passive house can be warmed not only by the sun, but also by the heat from appliances and even from occupants’ bodies.

And in Germany, passive houses cost only about 5 to 7 percent more to build than conventional houses.

The article reports higher costs in the US because some of the special windows and other supplies are harder to come by here.

This is still a pretty small scale phenomenon with only 15,000 passive houses built so far - most in northern European countries.

“The myth before was that to be warm you had to have heating. Our goal is to create a warm house without energy demand,” said Wolfgang Hasper, an engineer at the Passivhaus Institut in Darmstadt. “This is not about wearing thick pullovers, turning the thermostat down and putting up with drafts. It’s about being comfortable with less energy input, and we do this by recycling heating.”

There are now an estimated 15,000 passive houses around the world, the vast majority built in the past few years in German-speaking countries or Scandinavia.

You can't build this sort of house on a north-facing hillside or in a city street with a skyscraper shading your property. The development of this technology for cooling is nowhere near as far along.

I like this idea because it reduces our vulnerability to disruptions in energy flows in an industrial society. Loss of electric power doesn't mean a freezing house. The use of wood heating for this purpose doesn't scale as well due to limited supplies of trees. Also, putting wood on the fire is a chore and the resulting smoke isn't good for health.

Passive houses also reduce usage of limited supplies of fossil fuels, reducing pollution in the process as well as saving money in the long run.

By Randall Parker    2008 December 27 12:52 PM   Entry Permalink | Comments (18)
2008 August 16 Saturday
Ground Sink Heat Pump Demand Surges

Ground sink heat pumps are surging in popularity in the United States as the alternatives become much more expensive.

Though no comprehensive survey of the heat pump sector exists, Energy Department statistics on units shipped tell a striking story. In 2003, system manufacturers shipped 36,439 units. In 2006, the last year for which data is available, manufacturers shipped 63,683 units.

Bridgette Oliver, marketing and communications manager for ClimateMaster in Oklahoma City, the nation’s largest manufacturer of ground-source heat pump equipment, confirmed a rapid rise in sales. “Between 2005 and 2007, our revenue increased by 200 percent,” she said. “Our employees increased by 176 percent.”

Those are pretty small numbers when compared with the number of buildings constructed per year and even more so when we consider all existing housing stock.

One ground sink heat pump installer in Seattle claims a 5 year pay-back period.

There is a catch. A geothermal system costs more to install. Maloney believes that may be the reason why geothermal systems haven't become widely popular.

"Our costs are usually about 50 percent more than conventional equipment," said Maloney, comparing a geothermal system with a high-efficiency furnace, hot-water heater and air-conditioner installation. "That 50 percent you'll generally see back in about five years."

He estimates the cost of providing a conventional natural-gas system, including a furnace, air conditioner and water heater, might be $10,000. A ground-source geothermal system probably would cost $15,000 to $20,000, he said.

The payback period depends on what you are using now. If you are using oil the payback of a heat pump is a lot shorter than if you are using natural gas for example. Also, your weather matters as well. The capital costs pay back more rapidly if you have a lot of days where you need central heat or central cooling. Plus, you have to consider efficiency of each heat pump model. They aren't all the same in efficiency.

This comparative heating cost calculator will let you figure out how much you could save by switching to a lower cost way of heating.

By Randall Parker    2008 August 16 11:46 PM   Entry Permalink | Comments (10)
2007 November 22 Thursday
Heating Furnace Efficiency Mandates And Comparison Of Heat Sources

The US federal government isn't doing much to improve home heating furnace energy efficiency.

Under the new rule, the US Department of Energy (DOE) in 2015 will require nonweatherized gas-fired furnaces – the kind most used for home heating – to be 80 percent energy efficient. That's up from the current mandate of 78 percent.

...

But that slight uptick won't have much impact on natural gas use since 99 percent of furnaces sold are already at that level, industry data show.

The manufacturers didn't want to be forced to a higher minimum standard since that would make the cheapest gas burning furnace more expensive. That would cause them to lose some sales to heat pumps, oil furnaces, and other heat generators. Well, the industry got its way.

My guess is a higher standard would have been cost justifiable. I especially suspect that since I expect natural gas prices to go up faster than the overall rate of inflation.

Under the DOE's new efficiency standards, consumers will save $700 million and prevent 7.8 million metric tons of carbon dioxide from wafting into the atmosphere, over 24 years, DOE says. Had DOE instituted a 90 percent standard, consumers would save at least $11 billion and prevent the release of 141 metric tons of CO2 over the same time period, according to separate analyses from the American Council for an Energy Efficient Economy as well as Dow Chemical and the Natural Resources Defense Council.

Some states (at least Maryland, Vermont, Massachusetts, and Rhode Island) impose higher standards. So how much more do gas furnaces cost in those states?

Various heating devices come at more than one efficiency level. For example, heat pumps from the same manufacturer come at different efficiency levels. So if you want to get a new furnace or heat pump make sure you compare and consider how much efficiency you gain in the more expensive models.

I found a web calculator page for comparing cost effectiveness of different heating methods. Note that their default values for the energy sources are from a few years back and you need to put higher costs in for just about every energy source. For electricity use 10 cents per kwh or use the number for your state in that chart or check your electric bill. At the time of this writing heating oil in the US is averaging $3.21 per gallon. For propane the cost is $2.43 per gallon. At those prices a ground source (geothermal) heat pump is about a fourth the cost of oil or propane per BTU of generated heat. At least in the Baltimore area natural gas is going for about 92 cents per therm. That makes natural gas less than a third the cost of oil for heating. Geothermal heat pumps produce the most heat per dollar spent on energy inputs than other sources. But geothermal heat pumps also cost the most for initial installation ($18,000.00 to $35,000.00).

In colder climates where natural gas is not available the geothermal heat pumps already pay back quickly enough. Plus, since heat pumps run off of electricity their operating costs won't go up as fast as oil or natural gas. Natural gas prices are going to rise as US and Canadian natural gas production declines and as more users of oil shift to natural gas. But I do not expect the inflation rate for electricity to be as high as the inflation rates for oil or natural gas. Electricity has a long run cost ceiling that isn't much higher than the cost of electricity today because nuclear power only costs about 2 cents a kwh more than coal. Though electricity prices can go higher when fossil fuels start running out and before a lot of nuclear plants and wind towers can get built. But once oil production starts declining the cost advantage of using electricity to drive heat pumps will become much bigger.

Space heat and hot water account for about 4.9% of US oil usage. So a replacement all oil furnaces by geothermal and air heat pumps would reduce US oil usage by almost 5%. This is a shift that will pay for itself in dollars saved.

Update If you are considering putting in a wood boiler furnace regulatory risk should be a consideration. Many municipalities are restricting or banning wood boilers as heat sources due to air quality concerns.

Concerned about air quality and neighborhood disputes, Hampden joined a growing number of communities nationwide setting their own rules on the increasingly popular wood boilers, which are not federally regulated. The U.S. Environmental Protection Agency recommends emissions and air quality standards, but does not regulate where and when the wood-fired burners can be installed or used.

Rules are patchy on the state level, too.

Some states, including Connecticut and Maine, have regulations and let their municipalities adopt even stricter limits or ban the boilers altogether. Massachusetts has considered statewide rules but has not enacted them, while Michigan offers a model ordinance that local governments can adopt in the absence of statewide standards.

More sparsely populated rural areas are less likely to regulate the use of wood for heat. So if you have few neighbors you probably have minimal regulatory risk from spending $10,000 to $15,000 on a wood furnace. Though once fossil fuels production declines the rising demand for wood for both heating and biomass energy conversion will probably drive up prices of wood. My guess is electricity doesn't face as much upside price risk as wood.

Update: Migration of heating to geothermal heat pumps should be treated as an urgent matter. Why? See the October 23, 2007 CalTech lecture by Matthews Simmons "Is The Future Of Energy Sustainable" (PDF format). The production of oil is going to go into steep decline. We need to shift in advance as many processes as possible away from oil before that decline becomes steep and highly disruptive.

Update II: Also read the excellent Simmons Bermuda presentation (PDF format).

By Randall Parker    2007 November 22 11:01 PM   Entry Permalink | Comments (14)
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