The Mystery of Misapplied Mini-Splits

Inverter-driven mini-split heat pumps hold tremendous promise for slashing energy use for space heating and cooling in virtually every American climate zone. Equipment from some major manufacturers operates reliably to outdoor temperatures as low as -15°F, as described In our recent blog post on Cold Climate Air Source Heat Pumps. However, a long-time reader and past contributor to the Zero Energy Project challenged the low-temperature capability of mini-splits based on his experience in Massachusetts winters. He observed that his heat pumps did not heat his home below +20 degrees F. And he cited a discussion thread in Green Building Advisor that included some criticisms of mini-split performance in cold climates.

In addition to those comments, heat pump problems reported from the field have included excessive energy use and failure to maintain the comfort originally expected. These reports raise a critical question: how to achieve the promised performance of mini-splits in the real world. The answer is not a mystery — in a nutshell it is good design and installation .

A Fujitsu document sums up the issue: “According to a national survey well over 50% of HVAC companies do not size central heating and cooling systems the right way.” There are some smart, dedicated HVAC contractors that consistently install successful systems. Unfortunately, there is the other half that seems to cling to outdated practices, install poorly performing systems, and give this excellent technology a bad name. How can you ensure that you have a system that lives up to its potential? Whether you are an HVAC installer, a builder, designer, or homeowner there are some basic principles to follow.

Low Load Homes

It’s certainly possible to install a ductless mini-split in a conventional home with “typical” insulation and air sealing, but unless you improve the energy efficiency of the building envelope, it may not meet expectations. The best path in this situation would be to upgrade the insulation and air sealing before engaging a contractor to design a mini-split system. The result will be a heating system that is smaller, less costly, and more efficient, and home that is more comfortable.

For new construction with high insulation levels, low air leakage, and better windows, far less heating and cooling capacity is needed. But since energy efficient, high performance homes come in a variety of sizes and configurations, they have a wide variety of heating and cooling needs. So a successful mini-split system must be carefully matched to the thermal characteristics of the building. Every heat pump installation must be a custom design and not an application based on past experience with other homes or general rules of thumb.


Accurate sizing is not magic. It requires the use of reliable software that follows the industry standard Manual J. Wrightsoft and Elite are two examples of commonly used software programs, and some equipment manufacturers offer their own applications as well. Like any calculation, heating and cooling loads are subject to the old adage, “Garbage in, garbage out.” Each home’s thermal characteristics must be properly entered for the software to yield an accurate result. It’s critical that building insulation, air leakage, window performance, and solar heat gain be correct. The building’s location must be set to the proper climate zone and elevation.

The Manual J software calculates the amount of heating and cooling needed by the whole building as well as the amount needed in each room. A room-by-room Manual J load calculation is essential for proper HVAC design and occupant comfort.

Oversizing is a common problem. It’s often a response to an HVAC contractor’s fear of comfort complaints and call-backs. While large central systems also suffer from poor efficiency when oversized, they seem to tolerate the habit. This has led to oversizing becoming a common practice in the industry. It can result from inaccurate Manual J inputs or from the well intentioned, but mistaken, application of multiple “safety factors.”

One challenge is the simple fact that equipment comes in a limited number of sizes. If the calculated load falls between two standard sizes, most installers will select the larger size “just to be sure.” It’s common practice, but it can lead to problems for mini-splits. One solution is to closely match equipment capacity (size) to the calculated load. If the closest size is more than 10-15 percent higher than the calculated load, it might be best to slightly undersize the system. Any concern about the heating needs of small, isolated rooms or extreme weather can be addressed with small electric resistance heaters. This minor “insurance” measure will allow the mini-split to be sized more closely to the actual load range and run at peak efficiency while the house is covered for the most extreme conditions.

Equipment Selection

To properly size the heating system, it is important to understand the equipment. While inverter-driven mini-splits have the ability to adjust output, they have limits. Unlike the output of a gas furnace or a central heat pump, the “rated” output of a mini-split is not the whole story. To understand output over the entire operating temperature range, it’s necessary to study the specifications. The industry standard for proper equipment selection is presented in Manual S and should be used to select the most appropriate equipment. Good manufacturers offer design tools to help with equipment selection. HVAC contractors and HVAC designers should be sure to use a manufacturer’s sizing tools every time. To be sure that the model is suitable for a cold climate, check the list of cold climate heat pumps available from Northwest Energy Efficiency Partnership.


Some design problems grow out of a concern for distribution of conditioned air to all rooms. HVAC contractors are accustomed to extending a connection to every room. With a typical forced air system in a conventional home, this means a register ducted to a spot near a window on an outside wall. It’s no surprise that they would approach mini-splits in a similar way. It’s common to hear that an indoor unit is installed in every room using a multi-zone, mini-split system. This is seldom the best approach. Interior rooms without much exterior wall or window area will often have requirements far below the minimum output of the smallest indoor unit.

This horizontal ducted mini-split system is located in dropped soffit running down a hallway.

Mini-splits create an entirely new situation that requires a different approach from conventional systems — especially in zero energy homes. High performance features not only slash the total heating and cooling load, but they reduce drafts and increase comfort. Placing an indoor unit in every room is seldom necessary. The size and location of indoor units must match the comfort requirements of each room. Small rooms might need only an open door or a transom to stay cozy. Another option is to install a small transfer duct to connect a small space to a larger one. Air moves through the duct naturally or is driven by a thermostatically-controlled fan.

Multi-zone systems — in which two or more indoor units connect to one outdoor unit — work well, but offer the temptation to install an indoor unit in every room. This is good for distribution, but may lead to oversizing, because the outdoor unit must be sized to equal the sum of all indoor units. Again, it’s common for a very small room to have a load lower than even the smallest indoor unit. Not only does this lead to oversizing for that room, but it could also lead to an accumulation of excess capacity that may well be higher than the total load of the building. In high performance homes where multiple zones are needed, it may be more effective and possibly less expensive to install two or more single-head systems — referred to as a “one-to-one” approach — instead of one larger, multi-zone system. Good design analysis should consider both approaches and choose the better one.

Ducted Mini Splits

One great solution to provide heating/cooling to a group of rooms with relatively small loads is a horizontal ducted mini-split system. For example, one horizontal ducted system can serve several bedrooms, and a typical indoor unit covering the main living space. Some manufacturers offer a vertical air handler that connects to a branched duct system just like a conventional heat pump. An essential element of good design is making sure that comfort is delivered to all areas while keeping the overall system capacity in line with the total building load. Each duct run should be calculated to deliver the amount of conditioned air to each room as calculated by Manual J. Duct design is done according to Manual D.

Installer Training

The HVAC industry has a wealth of training resources for mini-split installers. The American Air-conditioning Contractors Association publishes the industry standards mentioned above and offers training on how to apply those standards. Most installers have a relationship with one or more equipment manufacturers who can provide training, technical materials, and individual consulting. Installers should take advantage of these offerings.

Smart Shopping

If you are a general contractor or homeowner hoping to invest in a mini-split system, you must find a contractor who is knowledgeable and conscientious. Even “reputable” contractors may not be the best choice unless they have the needed mini-split training and experience. Here are a few recommendations for due diligence.

  1. Get bids from three different installers.
  2. Ask them to describe the process they use to select equipment. It should include:
    • verifying the thermal characteristics of the building (insulation, air leakage, window performance, etc),
    • calculating equipment size with industry approved software
    • calculating duct diameter and length
    • delivering the right amount of comfort to each room
  3. What kind of training and certifications have they received?
  4. How many mini-splits have they installed? Ask for references.
  5. Before accepting a bid, review the full, multi-page Manual J report (not just the cover sheet) and check these for accuracy:
    • Is the climate and location correct?
    • Are the building characteristics (floor area, insulation, air leakage, etc.) correct?
    • Do the room-by-room load values closely match the capacity of the indoor units selected for those rooms?
    • How much “safety factor” has been added?
    • Is the total heating and cooling load within 10-15% of the rated capacity of the equipment specified? (There are quite a few variables that factor into this step, so the installer may have good reasons to exceed this range. The goal is to prevent unnecessary oversizing. If the equipment size falls outside this range, be sure that the installer has good reasons, and that they agree to stand behind the long-term performance of the system.)

Chances are good that any contractor that does all this will not be the lowest bidder. But that’s okay. Paying a small percentage more for proper heat pump installation will be money well spent — because it will provide low-cost comfort for decades while reducing carbon emissions.

Make Hot Water the Modern Energy Efficient Way

Water heating represents a big slice of the home energy use pie. As the housing industry moves away from fossil methane (natural gas), it’s essential to heat water as efficiently and economically as possible. The best water heating choice for getting your home on the path to becoming an energy efficient home is to install a heat pump water heater (HPWH). Here’s how to select, locate, install and operate one.


Modern HPWHs are about 300% efficient, meaning that for every unit of electricity consumed, three units of hot water are produced. The basic idea behind these extremely efficient water heaters has been commercially available for more than 100 years and is the same technology used in today’s household refrigerators.

Fossil methane is commonly used for water heating due to its low cost. While gas water heaters rely on less expensive fuel, a typical gas-fired tank is only 60% efficient and the most efficient tankless model tops out around 98% efficiency. At this stage in the evolution of energy efficient homes both tank-style and tankless gas water heaters should be off the table entirely for three reasons. First, natural gas is a fossil fuel that leads to even greater greenhouse gas emissions than are produced from burning coal. Second, heating water with a super-efficient HPWH has a lower life-cycle cost than heating with fossil methane. Third, building natural gas infrastructure into new housing developments and in new homes is an unnecessary expense. HPWH will serve this function without the added expense. It’s time to move past natural gas.

How HPWHs Work

A heat pump uses a refrigerant gas to capture heat from surrounding air. A compressor increases the pressure and temperature so that the gas condenses and releases its heat. This process cools the air around the water heater while pumping heat into the tank of water. As a result the space around the HPWH will be cooled and the air dehumidified as the water is heated.

Image: USDOE

Equipment Selection

Modern HPWHs have benefited from many years of research and development. All major water heater manufacturers now offer them with warranty periods of 6 to 12 years. Reliability has been quite good. Most products are called “hybrid” water heaters to reflect that all HPWHs also contain electric resistance elements as a supplementary heat source. Consumers can choose to operate them strictly with the heat pump or in combination with the resistance element.

In warm climates, just about any model of HPWH will work fine. These are called Tier 1 models. However, in colder climates, it’s important to select a Tier 3 model designed to operate efficiently at lower temperatures. Here’s a list showing the Tier 3 HPWH models appropriate for cold climates. Efficiency is expressed as the Uniform Energy Factor or UEF with higher numbers being better.

Tank Size

Rapid temperature recovery is important for all water heaters because as hot water is drawn it’s replaced in the tank by colder water. Heat pumps definitely take longer than standard electric water heaters to reheat the water, so HPHW tank size is important. Larger tanks help compensate for slower recovery. Since hot water demand is a function of how many people are served, select a tank capacity based on the number of people in the household. A 50-gallon model is sufficient for 2-3 people. Households of more than 4 will need an 80-gallon unit.


HPWHs need generous space for airflow and can’t be tucked into a small closet like standard electric water heaters. Generally, HPWHs need about 1,000 cu. ft. of space which would be, for example, an 11 ft. x 11 ft. room with an 8 ft. ceiling. Specific manufacturers may have slightly lower requirements, but generally speaking more free air volume around the unit is better. Ceiling height is also a consideration, because HPWHs tend to be taller than other water heaters due to the compressor and fan mounted on top of the tank.


The fact that a HPWH draws heat from its surrounding air leads to several important considerations for where to locate the unit. All HPWHs remove moisture from the air and produce a condensate. This water must be piped to a drain of some kind. A utility sink or floor drain are ideal. If an appropriate trapped drain is located farther away from the HPWH’s location, a condensate pump may be used to reach it

In climates that need a lot of cooling, a HPWH can be located in an indoor space that will benefit from the cool, dry air. In climates where homes need more space heating than cooling, HPWHs should be located in areas that are not heated directly but stay warmer than outside. The space must remain within the HPWHs operating temperature range of about 40°F to 90°F. Noise from the HPWH’s compressor motor and a fan is also a consideration. A location near bedrooms would not be a good choice.Taking all of these factors into account, a good location for colder climates would be a basement or garage that is insulated, but not heated directly, or possibly an indoor utility or laundry room.


HPWHs have some requirements for space, air flow, air temperature and noise management that don’t apply to conventional water heaters. Many or all these limitations can be sidestepped by using ducts to supply air to the unit and/or to exhaust air out of the house. All HPWHs offer optional duct kits that allow standard HVAC ducting to be attached. This opens a range of possibilities.

For example, the HPWH could be located in a small interior mechanical room or closet. A supply duct could draw air from outside in mild climates. In cooler climates, supply air may originate in a tempered space, such as a crawlspace, basement, or garage. Similarly, the cold exhaust could be directed through a duct to the outside — or in warm climates to an area where cooling is desirable. This arrangement allows the tank to be centrally located without reducing comfort or increasing space heating energy use.

Financial Factors

According to the the US Department of Energy, a typical household could save as much as $3750 over the 13-year life of a heat pump water heater compared to a standard electric model. This figure is based on national averages and may vary significantly depending on specific situations. In the process of designing a zero energy home, an energy model will give a much more accurate prediction of savings and how a HPWH meshes with other energy efficiency features. Many utility programs offer incentives for HPWHs – so check with your utility for details. They may require product and installation specifications.


Basic operation of a HPWH is not only easy, but may offer features that are more convenient than most standard water heaters. You can set the operating mode to “Hybrid” and walk away. This setting will ensure the high efficiency heat pump provides hot water whenever possible. When high hot water demand exceeds the capability of the heat pump, the built-in electric element kicks in to meet the need. Many HPWHs offer other helpful options, such as a convenient digital interface for setting water temperature, a mode called “Electric” or “High Demand” that locks out the heat pump and forces the electric element to do all the work, a “Vacation” mode that reduces energy use during long absences and triggers the water heater to resume normal operations on a specific day, and a control interface that allows the household to participate in a utility demand response program that reduces water heating operation during certain time periods in exchange for favorable electricity rates.

Hot water is an essential part of modern life but also a major contributor to residential energy use and carbon emissions. Installing a HPWH is a step in the right direction toward getting an efficient home on the path to zero energy.

Production Builders, It’s Time to Sell Zero Energy Homes

Production builders are uniquely positioned to identify and fulfill the needs of mass market home buyers. Most buyers assume that a new home is more comfortable, healthier, and more durable than an existing home, including the one they are leaving behind. Zero energy homes check all these boxes. Unfortunately, there is one misconception that prevents many production builders from offering zero energy alternatives. It’s the perception that zero energy homes are not affordable. In fact, zero energy homes cost less to own, provide their own buying power and build wealth starting the very first month.

The housing market is starting to change as the number of zero energy homes and zero energy ready homes grows steadily each year. Here are a few points for production builders to consider as they contemplate the pros and cons of joining the shift to zero.

  • Energy efficiency is slam dunk cost effective for the consumer. They can afford a slightly higher mortgage payment because the energy costs are lower.
  • This selling point must become second nature to the sales team and lenders.
  • Many builders are moving incrementally from their current construction practice toward higher efficiency.
  • A good first step is to have all homes certified by a third-party certification program, such as ENERGY STAR or Zero Energy Ready Homes.
  • Experience gained by participating in one of these entry level programs can be used to plot a course toward zero.
  • Energy modeling can be used to cost-optimize a package of performance features to get the most energy efficiency for the least cost.
  • While some builders start by offering zero energy options, it is best for builders to transition all their homes to high performance and then to all zero energy.
  • There are several successful production builders who have made the transition to 100% zero.

The biggest obstacle to production builders getting their developments on the path to zero is finding a way to pass on the higher initial cost to buyers while showing them that they are getting a better home with a lower cost of ownership. This is not a technical construction issue but involves educating customers regarding the high value they are receiving, finding the right financing vehicle, crafting an effective marketing strategy that meshes with the builder’s business model.

Sales Team Training

Successful production builders recognize the critical importance of an effective sales team, whether they are in-house or independent brokers. While it’s easy to see solar panels or a heat pump water heater, most energy saving features are invisible, so selling high performance benefits takes specialized knowledge and skill. Detailed broker training is available online and in person. Every person on the sales team must be enthusiastic about energy efficiency, knowledgeable about its benefits, and effective in communicating these points.


High levels of energy performance, along with the additional benefits of health, durability, and affordability, must be featured prominently in print and online advertising. Thrive Homebuilders in Denver is a good example of how energy features and benefits are presented on an equal footing with the common themes of location, finishes, and aesthetics.

Model homes must be staged to feature not only architecture and decor but must also highlight hidden energy performance features and benefits. One way to accomplish this is carefully executed signage that effectively identifies energy saving features and their benefits. Mandalay Homes in northern Arizona offers a good example of a production builder who has fully incorporated energy efficiency, water efficiency, and health into their business model and marketing.


It’s ironic that many production builders target the price-constrained end of the market, while virtually ignoring a major factor in the affordability of home ownership. While energy is no less significant than other monthly costs, energy efficiency offers the unique ability to pay for itself. The tangible result for the home buyer is a lower cost of ownership each month. If marketed appropriately, it will create a competitive advantage for builders at the lower end of the market. Monthly utility payments can be redirected into higher mortgage payments — without adding to the buyer’s overall housing cost, giving them a better home, and a profitable, long-term investment in the home’s structure and equipment.

The financing conversation needs to be re-framed. Consuming energy (and water) every month is an expense. Reallocating that money to efficiency features is an investment with an immediate return. The average homeowner spends around $1945 per year on energy, according to the latest official figures available from the US Department of Energy. Reallocating those funds to a 30-year mortgage payment would allow the buyer to finance additional loan principal of $39,000. That is more than enough capital to pay for the improvements, increase builder profit, and reduce the total cost of ownership for the buyer.

Applying zero energy features to a home is a sound financial strategy that turns an expense into a profitable investment for the home buyer. When monthly earnings exceed the monthly debt service, it’s called a profit. Zero energy homes are investments that bring their own buying power to the table. The return on investment can often beat returns from stocks.

This cold, hard economic advantage seldom finds its way into the sales and marketing efforts that sell homes. Savvy production builders leap over the first-cost barrier and show buyers how zero energy homes are good investments. Builders who can facilitate this investment will reap the reward of more sales and higher profits.


One way to overcome any first cost barrier is long-term financing, which is exactly what a 30-year mortgage is intended to do. Most mortgage lenders will acknowledge that lower monthly expenses equal higher qualifying income, and that means streamlined underwriting and higher loan values. Research also shows that occupants of energy efficient homes pose a lower default risk.

For conventional mortgages with buyers who can afford large down payments, mortgage qualification is not a big issue. These buyers have the capability to borrow enough principal to reap the rewards. It’s the job of the sales team to show the financial benefits to these higher income buyers.

It’s borrowers on the margin that may bump into income limits and other underwriting obstacles. For them, conventional guidelines often prevent lenders from taking advantage of a buyer’s greater buying power. Two relatively new secondary market programs address this issue. They are Greenchoice from Freddie Mac and HomeStyle by Fannie Mae. Both programs offer higher loan-to-value and debt-to-income ratios. If lenders are uninterested in these opportunities, builders must press the issue by demonstrating and documenting the added value of zero homes to lenders and appraisers. Some areas offer financing innovations such as PACE loans, or green banks, such as the one in Connecticut.

Production builders and their agents can clearly document the added value of these highly energy efficient homes. Then they can request the lender utilize appraisers with green appraisal training. If certified green appraisers are not available, they can fill out the green appraisal addendum and make sure that the appraiser uses it. These methods make financing available to lower income homebuyers and help them bring the higher initial costs of energy efficient homes within their budgets.

Shape the Market

Finally, every successful production builder has developed an approach that works for them. Many target affordability and effectively use the economies of large scale and corporate buying power as instruments of their success. While there may not be fat in the profit margin, there are many ways to cover the costs of greater efficiency within the finite “buying power” amount described above. These ideas for affordable zero energy design and construction can be applied to the zero energy home developments, so both developers and their customers benefit.

Of course, most businesses are reluctant to fiddle with the formula that brought them past success. However, the businesses that continue to enjoy success are those that embrace and to some extent shape the future. Production builders have the capability and responsibility to spearhead the zero energy homes movement.

It would seem that any business person would jump at the chance to sell a slightly higher priced, more profitable, product that cost less to own for buyers. With thoughtful design, careful construction, skillful marketing, and enlightened financing, zero energy homes provide production builders with a superior business model that pleases customers, adds to their bottom line and is good for the planet.

Unlocking the Added Value of Zero that Hides in Plain Sight

Most buyers and sellers in the housing market will agree that a high level of energy performance makes homes more comfortable. And after some investigation, most would accept these homes as being healthier, too. Most would admit that these homes cost less to own and might see them as a good long-term financial investment. There is a growing awareness that energy-saving features pay for themselves when the proper financing is available. Unfortunately, there are two closely related obstacles to the widespread adoption of energy efficient homes including zero energy and positive energy homes – the real estate appraisal and lending practices.

The appraisal industry stubbornly clings to notions of value and uses appraisal methods that lead to a widely-adopted false narrative: high-performance homes have no greater value than similar sized run-of-the-mill homes. Despite a series of research reports supporting the extra market value, appraisers in the field find excuses to ignore a huge source of value.

A new report adds to the weight of the evidence for higher valuations. Freddie Mac recently published Energy Efficiency: Value Added to Properties and Loan Performance. The study compared conventional homes to those that had received energy efficiency ratings, such as a HERS Index, and reaches these conclusions:

  • From the property value analysis, rated homes are sold for, on average, 2.7% more than comparable unrated homes.
  • Better-rated homes are sold for 3-5% more than lesser-rated homes.
  • Once borrower and underwriting characteristics are considered, loans in the high debt-to-income (DTI) bucket (45% and above) that have ratings appear to have a lower delinquency rate than unrated homes.

These findings support the conclusions of the earlier studies. Energy-efficient homes sell for more than conventional homes. The occupants of energy-efficient homes have lower operational expenses leading to more discretionary income. Energy-efficient homes have higher collateral value and impose less financial stress on their owners. These findings should justify consideration in the underwriting process.

Lenders gain something from energy efficient homes, too. These loans are more stable and profitable. A huge study of 71,000 mortgages in 2013 demonstrated that borrowers living in energy efficient homes are 32% less likely to default on their mortgages. It would seem that lenders would find additional value in these mortgages for two reasons. First, mortgage default is a substantial loss of ongoing revenue. Second, higher quality loans should have greater value in the secondary market and should bring a higher price when loans are bundled into securities. With hundreds of thousands of certified energy efficient homes already in the market, it’s surprising that smart investors haven’t already found a way to filter these higher value properties into higher value investment instruments. What would stop someone from assembling an ENERGY STAR tranche or a zero energy tranche. The same principles are also at work in the commercial real estate sector. Lower operating costs and greater financial stability translate into higher market value, shifting the perception of energy efficiency from that of a side benefit to an important business advantage that affects the bottom line.

In many ways, efficient homes and businesses have been flying under the radar. Multiple listing services (MLSs) and appraisal databases often don’t have a systematic way of capturing energy-saving features, ratings, or certifications. If data fields exist, they are unreliable because energy ratings and certifications are missing or erroneous. Some cities are addressing this issue by creating mandatory energy ratings. For example, Portland, Oregon’s Home Energy Score report is required for each home at the time of sale and the rating value is automatically entered into the home’s MLS listing. Several other cities in the US, such as Austin, Texas have developed energy disclosure policies, too.

While waiting for cities to take action and for the lending industry to catch up, homeowners and business owners, and their real estate agents, can take the lead by making sure the value of the energy saving features of their buildings being sold is properly appraised. There are now appraisers trained in valuing energy efficient features who can more accurately appraise the value of an energy efficient home or building. Ask your lender if they have an appraiser on their list who is qualified to evaluate energy efficient buildings. If you cannot locate one, be sure to document the energy saving features and equipment in the energy efficiency appraisal addendum and be sure that it is added to the appraiser’s report.While there is ample reason to acknowledge that everyone wins with zero energy homes, there is a persistent myth in the housing industry that high-performance homes aren’t worth more in the market. It’s clear that the added value is there, the lending and appraisal industries just aren’t looking. In the meantime, you and your real estate agent can do a lot to make sure that the energy efficiency benefits are added to the value of your building.

We Have Met the Enemy and It Is Waste

I remember the first time I saw Amory Lovins, a physicist who co-founded the Rocky Mountain Institute. He held up a compact fluorescent light (CFL) and declared that if everyone in the United States converted all the old-fashioned bulbs to this new lighting technology, 50 coal-fired power plants could be closed permanently, slashing carbon emissions. It was an astounding statement about the magnitude of energy waste in America. The year was 1985.

Unfortunately, America is still mired in wasteful buildings, equipment, and practices. According to Lawrence Livermore National Lab, about two-thirds of the energy consumed in America ends up as waste heat or “rejected heat,” – energy that is consumed but ends up not doing useful work, it’s just wasted. If two-thirds of the energy that flows through the American economy is simply wasted, there is clearly a lot of room for improvement.

Think of society as having an energy chain. To a small extent, we capture energy directly from the sun through agriculture and forestry. But most of the energy used in the human energy chain comes from fossil fuels. This fossil energy does work, such as growing crops, providing light and conditioned air, constructing buildings, manufacturing consumer goods, and providing services. At each step, a relatively small amount of work is accomplished, resulting in a thirty-three percent energy conversion ratio in the U.S. The majority of the energy we consume escapes as waste heat.

How can we reverse this situation to get more work and less waste from the energy we use everyday? The nascent revolution in personal transportation offers a good example. An internal combustion engine (ICE) is about 20% efficient at turning liquid fuel into motion. On the other hand, electric vehicles (EVs) convert more than 77% of the energy they consume into movement. Every time you apply the brakes in a fossil-fuel-powered vehicle, you waste energy as the brakes apply friction and release this energy as heat. In an EV, applying the brakes engages an electric generator that recharges the battery capturing a large percentage of the energy that would otherwise be wasted. (EVs have friction brakes too, but they are used far less often and as a result their brake components last longer.)

The upshot is that a standard ICE sedan will need more energy to go the same distance as an electric vehicle. One good example is the Kia Optima which offers the same vehicle with either ICE or electric drive trains. The ICE version will consume 2.4 gallons of gasoline to go 100 miles, or the equivalent energy of about 80 kWh of electricity. The ICE Optima has an EPA-rated fuel economy of 41 miles per gallon (MPG), making it one of the most energy efficient ICE vehicles available today. Even so, the electric version beats the pants off the ICE version with an equivalent EPA rating of 101 MPG. The EV will consume only 33 kWhs of electricity to travel the same 100 miles, which is equivalent to just a hair under 1 gallon of gasoline. Better still, the fuel costs just $4.50 for the EV compared to about $7.50 for the ICE. Who wouldn’t like that extra cash to stay in their pocket? The EV produces the same work, but uses about 60% less energy, produces far less air pollution and costs less. Although this example uses an extremely efficient ICE vehicle, the EV still proves to be far more efficient. Now imagine comparing an EV to a typical new vehicle with an average fuel economy of less than 25 MPG.

2020 Kia Optima

Internal Combustion Electric
EPA Fuel Economy 41 MPG 101 MPG
Energy to travel 100 miles 2.4 gal

80 kWh (equivalent)

1 gal (equivalent)

33 kWh

Average cost to travel 100 miles $7.50 $4.50

Waste Equals Opportunity

Amory targeted perhaps the most egregious example of waste when he waved CFLs from podiums in the 1980s. The invention that Thomas Edison patented in 1880 is sinfully wasteful. Only 4% of the electricity that goes into an incandescent lamp comes out as light. The other 96% is waste heat. Compared to the improved, but now obsolete CFL (70% efficient), today’s light emitting diode (LED) lights cost less, have greater efficiency (around 80%), provide better lighting, last much longer, and are free of the toxic mercury contained in fluorescents. So converting old incandescent and CFL bulbs to LEDs is an important step we all can take to reduce energy waste and minimize environmental burdens.

Combustion in Buildings

Other examples of waste involving combustion include water heating, conditioning inside air, and cooking. A conventional tank-style water heater burning fossil methane is about 61% efficient. Even super efficient tankless water heaters top out at around 98% efficient. That sounds good until you compare it to a heat pump water heater that can be 300% efficient at turning electricity into hot water.

While it may seem like magic, heat pumps can also keep homes and buildings warm and cool, with much less waste than combustion equipment such as gas furnaces or chillers. Mini-split heat pumps are widely used and readily available for conditioning air in homes or workplaces. In the kitchen, an induction cooktop performs like a gas range, but costs less to operate and doesn’t release toxic gases into the living space. We should all consider replacing old equipment with these advances in energy efficiency both in existing buildings and in all new construction. These upgrades will eliminate combustion from inside buildings and be a big step towards reducing energy waste.

Passive Approaches

It’s obvious that lights, appliances, water heaters, and HVAC equipment that directly consume energy are the main targets of this movement toward greater efficiency. These are sometimes referred to as “active” systems. However, there are many ways to reduce waste that could be considered “passive” – meaning without moving parts. The best example is buildings with more insulation, air sealing, and advanced windows. Reducing the heat loss and heat gain in homes and buildings is the most cost-effective way to maintain comfortable conditions inside, while reducing energy waste.

Amory had a pithy quote for this, too. “We’d find more energy in the attics of American homes (through energy conservation measures) than in all the oil buried in Alaska,” he said.

Those words seem especially prophetic at this time in history when the vast majority of petroleum and natural gas reserves must stay in the ground.

A Proven Track Record

The idea that saving energy is the same as making energy has been proven in the electric utility sector. In its most recent 20-year power plan, the Northwest Power and Conservation Council showed that energy efficiency programs in the region had saved enough energy to compensate for half the load growth over the previous 20 years. Looking ahead to the next 20 years, the council is projecting that it would be possible for up to 80% of the future load growth to be met through additional efficiency and renewable energy development.

The Future Must Be Renewable

Operating energy efficient equipment in well-constructed energy efficient buildings and powering our vehicles with renewable energy is by far the best option. During the transition to a fully renewable economy, we will all benefit by embracing electrification and energy efficiency. In the meantime, if the local utility is slow to move to renewables, we can install our own solar panels. The more efficient our homes, buildings, and systems are the fewer panels we will need.

And if you can’t switch to renewable energy right away, being efficient is it’s own reward. Fueling highly-efficient electrical devices with the fossil fuel generated electric power from the grid emits less CO2 than using so-called “efficient” on-site combustion systems to perform the same function.

Plan for Action

If tomorrow energy waste were reduced by half, it would mean that all the coal plants in the US could shut down immediately. The next time you feel heat, see an inefficient combustion-based system, or notice other energy waste in your home or work place, make a plan to change it.

Here are a few ideas to get started:

When it’s time to replace anything that uses energy, such as an appliance, light, or automobile, choose the most efficient option. Sometimes local stores don’t handle the most efficient or the least expensive options. It can pay to search online retailers for the highest performance and the best deal.

For major appliances and equipment, make a plan ahead of time. When the water heater springs a leak, the local plumber may not have a good selection of efficient equipment in stock. A quick trip to the ENERGY STAR website can help you zoom in on highly efficient products so you can be prepared to insist on a high-efficiency model when a replacement is needed.

When planning a home or building renovation, you have more time for thoughtful decisions. Check out the 12 Steps to a Affordable Zero Energy Home Design and Construction and these energy efficient renovation ideas. Be sure to choose construction professionals who share your commitment to efficiency and low-carbon living. A good place to start is the Zero Energy Project Builders Directory. Also look for local and state green building programs and check with the utility that serves your location to see if they have programs that incentivize energy efficiency improvements. Investing in energy efficiency can provide its own buying power, and with proper financing, earn dividends that begin immediately.

Time is running very short. Improving energy efficiency – starting now – is critical to avoiding the worst and most expensive impacts of climate change. With every consumer and workplace decision, large and small, we can reduce energy waste.

Which brings us back to Amory Lovins. He described using a nuclear reactor to spin an electric generator as “cutting butter with a chainsaw.” It appears that Americans overpower virtually every process of modern life. We can use a lot less energy to get the same result. While the laws of physics state that no energy conversion can be 100% efficient, we can do much better than 33%.

Is Cleaner Really Greener?

As a solar home owner, I’ve often wondered if it’s necessary to clean my solar panels. Dust collects during dry summer months, pollen and tree flowers accumulate in the spring, tree leaves and seeds gather in the fall, and snow piles up in the winter. The type and amount of material that accumulates on solar panels varies from locale to locale and season to season.

Any type of debris on photovoltaic (PV) panels can reduce electric generation as much as 10%, according to our local expert, Mike Hewitt at E2 Solar in Bend, Oregon. Researchers at University of California at San Diego found that dirty panels cut energy production by about 7.4%. Because of the high electric rate in San Diego, this reduction may cost the homeowner almost $100 per year in lost energy production. At my house in Central Oregon, I noted a 6.8% improvement in output after cleaning the accumulated dust off of my solar panels. My electric rate is half that in San Diego, so the dollar savings were much less. Clearly the economic benefit of cleaning panels will be higher if you pay more for electricity or if you’re living off the grid than if you are grid connected in a low rate area. This is good to keep in mind before you consider hiring someone to clean your panels or try doing it yourself.

Under most circumstances cleaning panels is just not worth the time. Most solar professionals advise owners to let nature do the work. Eventually, rain will wash away the dust, wind will remove leaves and other debris, and the sun will melt the snow. The amount of additional energy you get from a totally clean residential PV system seldom significantly exceeds the cost or the effort to clean them yourself, especially with the risk of falling off a ladder or roof. So for PV panels, cleaner is not necessarily much greener.


When Cleaning Might be Justified

Panels mounted at a lower angle are more likely to accumulate dust, leaves, pollen, snow, and other debris, and are more likely to need cleaning. My panels sit on a low pitched roof at 3-in-12 or about 11 degrees. The high-desert climate in Central Oregon generates lots of summer dust, which gradually accumulates on my collectors, so I decided to clean them in spite of prevailing expert advice. More disturbing than dust was last winter’s long freeze that piled about 30 inches of snow on the panels and that then refused to melt for six weeks. Even though I projected only a modest loss in production, I hemmed and hawed for several days. It wasn’t until I saw the panels start to bend under the snow’s weight that I knew it was time to clear them myself. In retrospect, I calculated that I lost 200 kwh of production or about 3% of my total for 2016 thanks to the prolonged snow cover. So anything that accumulates on the panels that cannot easily be removed by rain, wind or sun, such as bird droppings or algae growth, may justify the trouble of cleaning the panels, but even that is a judgment call.


Cleaning Tips

If cleaning your panels is required, or if you simply can’t resist the impulse, here are a few things to remember. Never spray cold water on hot solar panels. Thermal shock can shatter the glass. Therefore, clean or clear in the morning or when outdoor temperatures are mild. The simplest and safest procedure for removing dust and debris, which is sufficient in most cases, is to spray water from the ground, using a high-pressure garden hose or power washer. In some cases, using a long pole with a brush or squeegee attached will do the job, but be sure to watch out for power lines. Do as much work as you can from the ground or, if needed, from a sturdy step ladder. Climbing on the roof adds more risk and is best left to the pros.

I wash my solar panels the same way I wash my windows. I get up early on cleaning day so I am finished before the panels received enough direct sun to make them hot. A cloudy, cool day also works great. From an 8-foot, self-supporting ladder, I spray the panels thoroughly with water from the garden hose. The idea is to knock off all the loose grit. Next, I pull out the extension pole that I use to clean high windows. It has three sections and extends to roughly 15 feet. On the end, I attach a micro-fiber brush. With the panels still wet, I run the brush over the entire surface. Be careful not to miss any spots, because most solar cells are wired in series, shading one small spot can reduce the electrical output of an entire panel and one panel can compromise the efficiency of the others in that same string. When needed, I use a bit of dish soap solution for scrubbing and then rinse with a hose.

The greatest thing about photovoltaics is that the fuel they use – sunshine – is free. The next best thing is that most people, with the exception of neat-nicks like me, don’t need to do anything to keep their solar panels pumping out the free electricity.


Ice Dams Reveal Heat Loss Issues

Building Science Tells Us About Ice Dams

DSC_0660Last winter was an unusually cold and snowy here in my hometown of Bend, Oregon. As I walked through the snowy streets, I observed ice dams with their associated icicles cascading from roofs all over town. It paints a pretty picture, but the reality is that it’s very damaging to buildings. Ice dams growing along the eaves prevent water from draining off the roof as snow melts. It doesn’t take long for water to back up under roofing shingles and run into walls and ceilings. This damages insulation, gypsum board and, if uncorrected, can lead to structural decay. It’s sad that many of the homes I see with this problem were built in recent years, even though the solution is well known.

But first, let’s revisit the process that leads to this problem. An ice dam is caused largely by heat loss from a building. Warm air in the attic melts snow on the surface of the roof. As snow turns to water, it flows down to the eaves. The eaves are cold because they stick out into the surrounding air away from the building, so the water freezes. It doesn’t take long for a small glacier to form, and when the glacier gets high enough, water begins to back up. I’m seeing ice accumulations as thick as 10 inches here. Fluffy snow has an insulating value of about R-1 per inch, so a thick layer of snow can actually make the problem worse by isolating the roof surface from the cold, outdoor air.

When I teach building science to builders, designers and others in the construction industry. I always mention ice dams. It’s one way to emphasize the importance of two key elements of high-performance home design: air sealing and insulation. Improving these elements can greatly reduce, and even eliminate, the chances of ice dams forming in the first place.


Air Sealing

Much of the heat in an attic comes from warm air that leaks out from the living space. Small streams of indoor air rise through openings around pipes and wires. Recessed lights can be a major source of air leakage into attics. That’s one reason air sealing the attic is a key component of zero energy construction that we cover extensively here at the Zero Energy Project.


Forced-Air Ductwork

If ducts run through an unconditioned attic, they will increase the temperature and drive ice dam formation. When the heating system is running, air in ducts will be anywhere from 105 to 140 degrees F. Standard duct insulation is far lower than building insulation. Ducts have R-8, even in certified energy-efficient homes. Compare that with attic insulation that should be at least R-50. To make matters worse, ducts leak warm air directly into the attic. In new construction, it’s best to create a design that allows ducts to run through conditioned spaces rather than the attic. For existing homes, sealing the ducts can reduce leakage.


Insulate The Attic Perimeter

In most homes, the roof structure is built in a way that prevents adequate insulation depth near the eaves. The typical roof truss leaves little, if any, room for insulation above the top plate of exterior walls. This leads to snow melting in the perfect location to form an ice dam. Building scientists have been suggesting ways to increase the insulation value at the roof perimeter for decades. Ideally, the R-value at the perimeter should be same as in the middle of the building. trusses2Raised heel roof trusses can be ordered with the required depth at the point where the truss sits on the exterior wall. Vaulted ceilings offer a slight advantage in that rafters don’t pinch the space at the eaves the way that ordinary trusses do. Rafters framed with 2x12s provide enough depth at the eaves for sufficient insulation. While there are many solutions, we like the idea of using i-joists for rafters, because they can be 12 to 16 inches deep.


Cold-climate Roofs

In extremely cold climates, and especially those that receive an abundance of snow, the best approach is to place rigid insulation on top of roof sheathing in addition to the cavity insulation between rafters. Insulation boards are held in place with furring strips that also create a ventilation space. Placing ventilation above the insulation and below the roof sheathing is the gold standard for preventing ice dams.


Roof Ventilation

The key to preventing ice dams is to keep the roofing material as close to the outside temperature as possible. That’s one function of ventilation. Outside air is allowed to enter and exit through a series of vents. About half of these vents are located near the bottom of the slope while the other half are located near the top. Ventilation is required by code for attics and vaulted structures. Unfortunately, deep snow can cover vents located on the upper surface of the roof, making them ineffective for preventing ice dams. Vents located in soffits actually displace the much-needed insulation in it’s most critical location. One solution for soffit vents replaces a typical cardboard or plastic vent baffle with a sheet of rigid insulation. The sheet is positioned to direct air into the attic space above the fiberglass insulation. Depending on its thickness, the rigid insulation could provide R-5 to R-10, which, while a touch low, is certainly better than nothing.


Bottom Line

It’s true that all these ideas cost more than typical construction. But they are far less expensive than repairing damage from ice dams. All the solutions outlined above have the added benefit of improving energy performance and saving money, proving that the investment in good design and smart construction practices comes back in performance and durability.
We seem to view ice dams as a result of the weather, and therefore, beyond our control. Instead, we suggest assigning blame for ice dams to construction practices. That gives builders and designers the opportunity to take a risk and turn it into a benefit.


On-Site Storage, the Great Equalizer

We are now in a world where decentralized electricity production, such as rooftop solar, is more viable than ever for the public and more threatening than ever to utilities. The public is more willing to adopt in-home renewables thanks to reliable technology, solid performance, declining costs, and the growing availability of loans. Utilities are threatened by uncertainty about how to integrate thousands of new decentralized energy sources into the existing network. And ratepayers without rooftop solar are fearful that their rates will rise. On-site energy storage is one new technology that promises to address all sides of this dilemma.

The Need for On-site Storage Technology

As companies such as Tesla/SolarCity and Mercedes produce more affordable batteries for electric vehicles, energy storage technology is spilling into the housing sector. Grid connection is essential for zero energy buildings which need to bank excess production from sunny times to use at night and on cloudy days. The disconnect between when energy is produced by solar panels and when it is needed to meet peak demand remains a problem. On-site battery storage offers a solution.

While utility-scale, grid-based storage is coming online in California and Hawaii, battery products can now be installed behind home electric meters and intelligently integrated with the grid. Tesla’s new Powerwall 2 includes a built-in inverter that converts the direct current from panels into alternating current for household use and exports power to the grid when energy is most in demand. Thinking big, every one of California’s  “million solar roofs” could easily contribute to the overall energy mix making the energy grid more efficient.

On-site storage allows solar owners to store excess energy for later use, even during a power outage. Residential scale batteries hold between 5 and 20 kWh of electricity. This is in the same range as the 15 to 20 kWh used per day by a typical newly-constructed American home. Batteries currently available will help a typical zero energy home even out the peaks and valleys of daily energy fluctuation.

The Challenge of Net Energy Metering

Most utilities have reluctantly agreed to “net energy metering” arrangements when negotiating rate cases with state regulators. Net metering means that utilities accept energy from decentralized sources, although contract terms vary widely around the U.S. The phenomenal growth of these systems shows huge promise for addressing climate change, pollution and national energy security. When there were few decentralized producers, mostly rooftop photovoltaic arrays, there wasn’t much problem for the grid. Unfortunately, electric utilities are largely dealing with an electricity grid that doesn’t look much different from the days when George Westinghouse and Nicola Tesla installed the first large-scale powerhouse at Niagara Falls. The grid is in desperate need of a 21st Century upgrade in order to better meet peak demand and integrate decentralized energy production.

Benefits for Owners and Utilities

Utilities benefit from on-site storage in two ways. First, they don’t have to supply power to the home during peak hours. Second, with smart integration and a fair net-metering agreement, utilities could pull stored energy into the grid to meet a short-term need. Later, when demand subsides, batteries could be recharged with grid power or the customer could be paid a fair price for the amount of energy he or she supplied.

On-site storage is good for solar panel owners, because it allows power shifting from daytime production peaks to evening consumption peaks. Few zero energy homes use as much energy at midday as they produce. But when evening arrives, families begin to use lights, appliances, and energy-sucking devices like game consoles. On-site storage allows them to use banked energy to offset evening use when demand and utility production costs are higher.

Whether specific customers benefit from on-site storage depends on how they are credited for power returned to the utility under their net metering agreements. One factor is the timing of credit expiration. Some agreements generously set an annual expiration, usually each Spring. This allows credits to accumulate over the sunny months to be used during the cloudy winter months. These customers don’t have much to gain from on-site storage other than as an emergency back-up, because they gain full value for the excess energy they return to the grid. In other agreements, credits may expire each month. During sunny months that could mean leaving hundreds of kWhs on the table. For these customers, batteries allow the excess energy from each day to be used that same night. This reduces the amount that would be lost each month, and saves the customer money.

Under some net metering contracts there is a difference in the customes’ buy price and their sell price. These customers receive a lower price when selling excess power than it costs them to buy power from their utility. The sell rate is often based on the utility’s wholesale power costs, which can be anywhere from 20% to 50% of the retail price. Solar owners may generate excess power during the day and sell it at the wholesale rate, but buy power later the same day at the full retail price. Batteries store excess power on-site, so customers use it themselves. This replaces power that they would have purchased from the utility at the higher retail price. In essence, on-site storage allows owners under these types of net metering contracts to capture the full retail value of the energy they produce.

Time of Use Pricing

There is a third possible scenario that would benefit a solar/storage setup most of all and it involves time-of-use pricing. Although uncommon, this rate structure changes prices to reflect the actual cost of utility power. The most expensive energy coincides with the highest demand for electricity, which usually occurs in late afternoon or early evening. Retail customers would save money if they used batteries to carry them through the high-priced peak. This would be true even if the batteries were charged with grid power rather than solar.

A Win-Win-Win Solution

The grid will still be needed to address the bigger seasonal fluctuations from sunny seasons to cloudy ones. However, on-site storage can be valuable to consumers and utilities as it balances daily supply and demand variations. In the future, successful grid integration will require each zero energy building to capture excess production on site for later use and make that stored energy available to the grid as needed. Properly done, it will make the grid more efficient and keep energy prices lower for everyone. On-site energy storage will be a benefit for homeowners with solar collectors, for electric utilities, and for ratepayers without solar. It’s the kind of win-win-win solution the world needs to make the shift to mainstream zero energy living.

Solar Prices Keep Dropping

Prices for installed solar electric systems dropped again in 2015. Residential systems are 5% cheaper and commercial systems are 8% cheaper than the previous year. Tracking the Sun, an annual report published by Lawrence Berkeley National Laboratory, follows upfront cost before incentives. Prices for residential scale installations in the U.S. have dropped consistently from $12/Watt in 1998 to about $4/Watt in 2015 with some leveling off in the last few years. From 2008 to 2012, the main driver was a steep decline in photovoltaic (PV) module prices. Since 2012, module prices have remained relatively flat, while other components (inverters, mounting) and soft costs (labor, administration, marketing) have dropped faster. As system prices have declined, governments and utilities have deliberately reduced incentives, which now stand at less than $1/Watt in most areas.

Of particular interest is the relationship of price in the U.S. compared to other countries. While hardware costs are similar across countries, the authors assign the higher costs in the U.S. and Japan to soft costs, which might include business models, interconnection standards, labor rates, and incentive levels, among others.


Not surprisingly, larger systems cost less per Watt. A typical 4,000 Watt system comes in around $4.50/Watt, while a 20,000 Watt system drops to $3.60/Watt. The report notes significant differences between states with Minnesota and New Mexico at the high end. Nevada and Texas cost the least. Most states are below the median price, but large numbers of installations in higher-cost states, such as California, New York and Massachusetts, push the national median higher.

While high-volume installers showed lower prices in Arizona, that wasn’t the case in other states where there was no apparent relationship between sales volume and price. Of particular interest to zero energy builders, installation prices were substantially lower in new construction than in retrofits. This may be due in part to the economy of scale in housing developments. Tax-exempt customers, such as schools, government, nonprofit and religious organizations, paid more than residential buyers, although the price has declined for all customers over the years.

The steady decline in the price of PVs, has supported the growth of zero energy buildings. Although module prices have probably reached their low, other hardware components still have room to drop. More importantly, soft costs still offer substantial opportunities. Incentives are likely to target these areas in the near future. Continued growth and evolution in the solar industry is good news for the zero energy movement.

Induction Cooks Better than Gas

Induction cooktops have been dropping rapidly in price. I recently acquired two, single burner induction units plus a set of stainless steel cookware for $100. At those prices, you might want to consider retiring the old electric or gas range. There is no doubt that induction uses less energy than an electric resistance burner, but comparing it to a gas burner is more complicated. Thanks to Paul Scheckel, author of Home Energy Diet, we now know that induction cooking is 74% efficient while gas is only 32% efficient. Other sources show the efficiency of induction even higher, making 74% a conservative figure. Induction also heats faster. In Paul’s test, water boiled in 5.8 seconds using induction, while it took 8.3 seconds to boil the same amount of water with gas.

If you live in a zero energy house and power your electric cooktop and oven with solar it is, in Scheckel’s words, “fossil-free cooking.” If you’re living in a conventional home and want to chip away at your carbon footprint, you’ll want to consider the carbon emissions of your fuel choices. Burning natural gas directly to get 1 million btus releases 117 pounds of CO2. Burning coal directly for the same amount of energy would release just over 210 pounds. There aren’t too many people burning coal in the cookstove these days, so it makes the most sense to compare the total system efficiency of electricity with that of gas.

In Scheckel’s experiment the electric induction cooker released 0.29 pounds of CO2 to heat the water, while burning natural gas released 1.16 pounds. (CO2 emissions from propane are even higher than natural gas). So, even taking into account the gross inefficiency of coal-fired electricity, induction cooking dramatically reduces carbon when compared to gas (or to less efficient standard electric cooktops).

In addition to reducing energy use and increasing cooking speed, induction cooking has several more advantages. The electronics allow a wide range of programming. You can start, stop or change temperatures at pre-programmed times. You can precisely set the temperature by degrees. The durable glass top doesn’t get hot, so fingers don’t burn and neither does spilled food, making cleanup easy.

Induction cooking works by creating an electromagnetic field (EMF) that excites the molecules in cookware. So, you need pots and pans made with ferrous metal, i.e., stainless steel or cast iron. If you don’t have those, then you may need to buy new cookware. Those issues aside, induction cooking is safe, efficient, and a perfect addition to a zero energy lifestyle.