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Zero Energy Design® Passive Solar Concepts and Technology Summary

Energy Is Arguably The Most Important Issue
Facing The Entire World Today

The following is a quick summary of many Zero Energy Design® (ZED) technologies that we have comprehensively integrated into our unique holistic systems design and formal engineering process, for over three decades, since 1979. The following short overview is intended to “wet your scientific appetite” and motivate you to invest the time required to read on, and better understand the energy-problem-solving potential of our well-documented proven ZED solutions. Does your poorly designed and constructed building have heating and cooling bills? IT DOES NOT NEED TO!

It has taken us decades to accumulate, develop and refine this valuable ZED knowledge. Much of it is “counter intuitive” to business-as-usual Architects and Builder, who are very unfamiliar with energy science. We attempt to summarize our successful design patterns in a concise form that is easy for intelligent people (who know how to read in depth) to understand and appreciate.

ZED wishes to fully acknowledge the significant research and wonderful public-domain contributions published by the world-renowned University of Central Florida, Florida Solar Energy Center . Since 1975, they have provided valuable input that is an integral part of ZED. We have always considered their basic foundation, and added our own experiences and creative innovations on top of the best design and construction practices offered by the many energy experts we have encountered over the years. FSEC grew to about 60 researchers, many working on a $5 million NASA hydrogen program grant.

When I developed my 5,000 sq.ft. Zero Energy Design® Home in 1979, I was a Senior Research Scientist at a large energy research lab with 700 research scientists – 550 of them had leading-edge PhD-level expertise in thermal mechanics, and the essential skills that I needed to perfect ZED in a minimum amount of elapsed time. It was a fabulous time of intellectual growth for me before designing our unique 5,000 sq.ft. 1979 indoor-swimming-pool home, which received widespread international press coverage, and support from the U.S. DOE and ORNL..

As a second-generation energy research scientist, I have always solicited and appreciated input from multitudes with widely-varying intuitive, anecdotal, irrational, and scientific opinions. ZED has listened closely to the considerable constructive criticism we have received, and made decades of iterative refinements along the way. What we offer here is our proven assimilation of the “best and brightest” thinking we have discovered, tested, and improved upon along on our journey toward resolving the ever-increasing great American energy crisis

ZED cannot be digested in a 60 second sound bite by non-learning TV addicts with a short attention span. In writing my encyclopedic ZED material, we obviously hope and assume that YOU will take the time required to merge our experience with your own critical decision making processes, and become healthy, wealthy and wise from the time you invest exploring ZED possibilities, and our practical solutions developed over the decades. (smile) The longer you study a challenging problem with an open mind, the more chance you’ll have of working out all of the subtle issues you encounter over time.

"Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for." - Socrates

Albert Einstein said that if we cannot explain something to a six-year-old child we really do not understand it at all. His enlightened statement is very stimulating. We will do the best we can to help you become aware of what is now a formal set of ZED principles and practices – How and Why. If you care about energy conservation or living an abundant life in harmony with nature, then please take the time required to read and absorb this valuable information.

This quick outline does NOT explain everything you need to know to make it all happen. We are merely providing a snapshot of a 50,000-foot-high view of some of the categories of expertise required to solve the world’s current complex energy problems. There is a lot of physics and math behind what has become “intuitive” ZED to us in hindsight.

We will elaborate on the history, science, systems engineering, trade-offs, economics, esthetics, logistics, materials, products, practical construction techniques, and community planning issues on later web pages, and in our books, plans, specifications, Construction Checklists we are adding new detailed specifics every week right now.

We also offer classes and turnkey project consulting for architects, designers, developers, builders, tradesmen, executives, investors, teacher / professors, students, hands-on interns, politicians, and potential Zero Energy Home buyers. Our 25 years of practical ZED demonstrations have shown that the remaining issues in front of us are educational and political, more than technical.

Passive Solar Techniques and Thermal Buffering

To understand why our ZED Thermal Buffer Zone (TBZ) is so effective, we need only a fundamental understanding of the mechanisms of heat transfer. A simple engineering calculation of conductive heat loss through a wall is to take the difference in temperature on each side of the wall (Delta T) and divide it by the thermal resistance (R factor) of the wall. In a conventional house, if the inside temperature is 72 degrees and the outside temperature is 20 degrees the Delta T is 52 degrees (72 – 20). The larger the Delta T, the more heat is transferred. The lower the R factor, the more heat is transferred, and the higher your heating AND cooling bills will be.

If the R factor of the wall is R11, the heat loss will be 52/11 or about 4.73 BTU/HOUR /sq.ft. Houses with a lot of “architecturally attractive” cuts and jags have a high ratio of surface area to interior living space, and thus loose a lot more energy through their walls. A simple rectangle has less surface area to interior living space ratio, and thus requires less energy to maintain comfortable interior temperatures.

In a ZED double-shell home, if the inside temperature is 72, the outside temperature is 20, and the TBZ averages the 58, the Delta T is only 14 at each interface point. If the R factor of the inner wall is also R11 the heat loss will be 14/11 or about 1.28 BTU/HOUR/ Sq.Ft. (.27 of the single-envelope house). TWO SMALL DELTA T’S ARE MUCH BETTER THAN ONE LARGE DELTA T (where have I heard that energy science before?). How many architects do you know who live in a ZED double-shell home? Should you pay a dumb AIA architect to design your next building with any heating and cooling bills?

In this simplified illustration, the ZED double-shell made the inner house retain heat 3.7 times longer than a conventional single-envelope house. The more extreme the outside temperature (Winter and Summer) the more important the ZED thermal buffer becomes. If the wind is blowing outside, the wind chill makes the double-shell even more important. In this example we have not even considered the valuable reduction in outside infiltration and radiant heat transmission. We discuss these elsewhere, but for now, in simple summary: TWO SMALL DELTA T'S ARE MUCH BETTER THAN ONE LARGE DELTA T. We repeat because this is so VERY important, and overlooked by so many arrogant ineffective Johnny-Come-Lately GREENWASH ARCHITECTS, who are NOT energy research scientists or ZED engineers.

The ZED Passive Solar Thermal Buffer Zone (TBZ)

(introduced in Chapter Eleven) is extremely valuable thermally and aesthetically both winter AND summer. Two small Delta T’s are always better than one larger Delta T, whether the exterior is below freezing with wind chill, or hot and humid with a high apparent temperature heat index. The beautiful large glass area of a ZED solarium is ONLY possible with a Thermal Buffer Zone design, since it would be a thermal disaster on a single-shell home in a hot climate. In quick summary, the ZED Thermal Buffer Zone summer design:

(1) Helps reduce or eliminate most conventional cooling energy requirements, and

(2) Allows the most attractive visual home designs, and natural daylight throughout the entire home, of ANY architectural alternative design pattern available today.

We introduce “Passive Solar Cooling – Use Sunshine To COOL Your Home” in Chapter Six of our ZED eBook. Everything we discussed there applies to Thermal Buffer Zone home cooling.

We start with the basics of summer energy conservation, cool roof, radiant barrier roof decking, no west facing glass and well-insulated (low infiltration) roof, ceiling and walls. We make sure that things like clothes dryers and fireplaces are NOT sucking cool air out of the inner living quarters, and replacing it with hot, humid, dirty, unfiltered air from outside. We eliminate incandescent lighting and inefficient appliances. Minimized photovoltaic systems give us some solar-powered electricity to work with.

Where auxiliary air-conditioning and interior dehumidification are required part of the time, we are careful to NEVER run any air ducts in any unconditioned space (like the garage or the attic).

A Nutshell Summary Of Designs To Avoid in a true Zero Energy Home

Never Design A Complex Exterior with a high ratio of surface area to interior space – Excessive surface area causes unnecessary undesirable heat transfer summer r and winter. A simple rectangle costs less, performs better, and has less surface area and less turbulent airflow. Simple architectural features can be added to a rectangle to improve street appeal. Look at our Florida ZED Home for some ideas.

Making a Square ZED Home Fancy

Never Use 2 x 4 Wooden Exterior Walls On 16” Centers – 2 x 6’s on 24” centers are better, but ZED recommends "Tree Free" construction - use less wood, cost less, and allow more insulation. Use simplified 2-stud corner details, wall intersections, etc. Other non-wood alternatives have many advantages over wood framing. There are many modern good reasons to not use wood to frame a home.

Never Use Log Home Exterior Walls – Wood has much less-insulating effect per inch than other superior less-expensive materials, and logs waste a large quantity of a dwindling natural resource. Killing trees is bad for the environment and increases Global Warming.

Never Design A Long Distance Between Hot Water Source and Faucet - Wastes time, water, and energy to heat the replacement water. Use plumbing clusters (and possible re circulation just before hot water usage).

Never Design A Frequently-Used Single Exterior Door - ZED often uses a 2-door “airlock” in the thermal buffer zone. One door is shut before the next is opened, reducing the large volume of air infiltration on windy days.

Never Use Much Glass on a single-shell portion of the house – It is like a thermal hole in your walls. The ZED double shell design allows much more glass, daylight and views, with less undesirable heat transfer. Two small Delta T’s are better than one large Delta T.

Never Use Incandescent Lighting – Century-old Thomas Edison incandescent lighting is the least efficient way to provide light. It is the most common, least expensive to install initially, BUT incandescent lighting uses far more electricity, and is the most expensive to operate and maintain. Fluorescent lighting is much more efficient, but most of them have undesirable color temperature. RGB ultra bright LED’s are more expensive, but they are by far the most efficient, with the lowest total cost of ownership, and they allow full spectrum color control.

Never Run Electrical Wiring or Plumbing In Any Exterior Wall – They create poor insulation and air infiltration holes in the building thermal envelope. They can be run in the interior walls that are perpendicular to the exterior walls, or in air-sealed floor outlets, etc. All perforations in the building envelope (including interior wall / ceiling / attic / plumbing / electrical / lighting) must be carefully sealed and inspected. The goal is to eliminate unplanned air infiltration.

Never Design An Open Staircase Or Loft Area in the air-conditioned portion of a building – Warm air rises like a hot air balloon. The upstairs will ALWAYS be either too hot, OR the downstairs will be too cool (or both). A staircase should have a door at the bottom (preferred) or at the top. The staircase may have optional glass looking into a great room for visual appeal. Glass elevators are nice in more-expensive homes. An open staircase or balcony works well in a double shell thermal buffer zone (sunroom) where a ZED convection airflow loop is engineered to automatically equalize upper and lower temperature differentials.

Never Overlook Any Of The Critical Human Comfort Issues – Temperature PLUS humidity (enthalpy), oxygen and CO2. Intelligent Heating Ventilating and Air Conditioning (HVAC) sensors and controls are desirable on larger homes and commercial buildings. Inexpensive intelligent programmable zoned HVAC with multiple sensors and controls can be used to help balance comfort factor differentials north/south, east/west, morning/afternoon, upper/lower, inside/outside, etc. - improving comfort while greatly reducing energy requirements.

Never Use Roof-Angled Glass (Skylights)– They create a Solar Furnace in the summer. In the winter, warm air rises and heat is rapidly lost through the cold conductive glass. Roof angled glass is always bad everywhere in every season. Eve n on sunny winter days, roof angled glass provides LESS solar gain than vertical south facing glass (in the northern hemisphere).

Never Use A Fireplace or A Clothes Dryer In Air-Conditioned Living Quarters- They suck out your expensive clean conditioned air, which must be replaced by unconditioned dirty air. ZED locates the laundry room in the un-air-conditioned thermal buffer zone. Folding and ironing can be done in comfortable interior rooms.

Get Much-More Information in Larry Hartweg's 850 page ZED eBook on Zero Energy Design EBook or CD ROM .


Two Small Thermal Delta’s Are Much Better Than One Large Thermal Delta- ZED

Some of the walls in a ZED home involve the important use of two thermal barriers with a thermal buffer zone between them (like a solar greenhouse and the SUPERINSULATED roof / attic / ceiling). When the buffer zone is maintained at a temperature BETWEEN the exterior temperature and the interior living quarters temperature, there are TWO SMALL DELTA T’s (temperature differentials) instead of one large one, which yields a MUCH lower heat transfer than single wall conventional construction. Lower delta T’s mean lower conductive, convective, and radiant heat flows – This is a VERY IMPORTANT ZED ENERGY CONSERVATION PRINCIPLE! (Often overlooked by most others)

When a single wall exists between the interior and exterior temperature extremes, special care is taken to minimize heat transfer by conduction, convection, and especially radiation (the most significant heat transfer mechanism). Quality control insures that cavity space insulation is neither too long (compression bends), nor too short (gaps), and that all exterior air gaps are filled, and insulation is NOT going to settle over time, creating future problems.

Undesirable air infiltration (common conventional construction air leaks) are of significant ZED concern. It is difficult to seal a home when it is first built, and over time air leaks gradually become worse. To see how bad it is in your current home, the U.S. Department of Energy recommends lighting an incense stick on a windy day and holding it next to your windows, doors, electrical outlets / switches, plumbing fixtures, and any other spot where there's a possible air path between the interior of your home and the exterior. If your windows “whistle” on windy days it is NOT a sweet sound - you have serious air leak problems that may be difficult to correct. Even interior wall electrical outlets (on the ceiling or vertical interior walls) can leak air to the attic, etc. Recessed ceiling lights are almost always air leak problems. There can be air leaks under the base plate of an exterior wall where it sits on uneven concrete.

In new construction ZED houses in cold northern climates, where the number of degree days of heating far exceed the cooling requirement, vapor barriers are used on the heated (interior) side of the wall to prevent moisture build up inside the wall cavity space of exterior walls and ceilings. (If humidity condenses and is trapped inside convective-cavity-wall insulation, it acts like a wet sponge and loses most of its conductive R-value, since water is a good thermal transfer medium). ZED homes normally do not allow plumbing or electrical wiring in any exterior wall.

In contrast to cold climates, in warm climates (where the number of degree days of cooling is much larger than the heating requirement), air infiltration barriers (and radiant barriers) are placed on the outside of walls, without interior vapor barriers, since the outside of the wall is the hotter side most of the  year.

To minimize common air infiltration sources, ZED does NOT allow perforations in exterior walls (for plumbing, electrical wiring, etc.), (or they are minimized and very carefully sealed before they are covered up). This sometimes requires clever placement of interior electrical wiring, fiber optics, and plumbing to avoid running any lines in the thermally sensitive exterior walls. Plumbing and wiring (switches and outlets) can often be run in walls that are perpendicular to the exterior walls. Floor outlets can replace exterior wall electrical outlets, etc. Exterior wall framing techniques at house corners and perpendicular wall intersections often make it difficult or impossible to properly fill the space with insulation. ZED specifications show innovative framing details to make sure this does not happen, and every cubic inch of exterior walls is filled with uncompressed insulation (or less thermally resistant wood).

When a wooden stud wall sits on a concrete foundation, there is often significant air infiltration between the bottom (sill or sole) plate of the wall and the uneven concrete surface. Frame carpenters can rapidly layout the walls on the slab and stand them up with no concern for air leakage between the wood and the uneven concrete. The lack of a good air seal between the bottom plate and the foundation can account for 10% to 50% of the undesirable air leaks, AND pest entry, into the home. This can be eliminated by carefully applying a generous amount of oil-based sealant before standing up the wall. Carpenters do not normally do this, so it requires quality control supervision at the critical moment when this process must be done. After the wall is in place, it is difficult to ensure that the infiltration seal was properly installed.

Another superior technique to obtain a good air-and-moisture seal is to roll out a layer of polyethylene foam “sill plate sealer.” It is slightly wider than the sill plate, and thus can be easily inspected to ensure that the carpenters installed it properly. The polyethylene sill plate sealer foam automatically fills (all but the largest) irregularities between the wood and concrete foundation.

It is critical to essentially eliminate uncontrolled air infiltration to reduce heating and air conditioning costs, prevent water and insect intrusion, and future structural damage (from sill plate rot) when inexpensive wooden stud walls are used, instead of concrete wall construction.

Concrete wall construction normally has much lower air infiltration than wooden stud walls, but it is more expensive. When concrete exterior wall are used, we recommend Insulated Concrete Forms (ICF’s), which add cost, but reduce labor cost to thoroughly insulate the concrete walls’ high thermal mass.

In ZED homes, we don’t normally allow any plumbing or electrical wiring in the exterior walls. This eliminates perforations in the bottom (and top) plates of exterior stud walls, and it greatly simplifies sealing the exterior home envelope against air infiltration

Passive Solar Radiant Barriers - How to make them work well during hot summer days- ZED

It is VERY IMPORTANT that the roof and west wall have effective “radiant barriers” of the house to block solar heat gain through the roof and hottest afternoon wall. Conduction and convection are significant thermal transfer mechanisms in sideways heat transfer through shaded walls, but radiation is just about the only mechanism that causes downward heat transfer through roofs into your hot attic and interior ceilings (something that very few architects understand).

A conventional house attic can be more than 40 degrees hotter than the peak outside daytime air temperature. Naive Americans just assume that this has to be, but it does NOT. In stark contrast to a conventional house with hot attic, our ZED attic space acts like a Buffer zone, with a temperature that is LOWER than the peak outside air temperature. (which cannot possibly be cooler an the outside intake air temperature). On the hottest Summer days, you would rather be in a ZED attic, than outside. This surprises almost everyone.

Installng Radient BarrierDoes “fiberglass insulation” block radiant heat flow? NO, not very well! Radiation goes right through glass, even if you spin it into small fibers. Hold some fiberglass insulation up to the sun and you will see the light. The Florida Solar Energy Center has documented the fact that a radiant barrier can reduce the heat flow through standard insulation by an impressive 40%.

“Conductive heat flow” R-value is NOT the critical issue in blocking Summer solar radiation through the roof into your very hot attic. Radiant e shines on it. It IS very important that radiant barriers have at least a 3/4 inch air gap on one side of them (or conductive insulation like Dacron, etc.), to also block conductive heat flow. How do we do this cost effectively, with no additional labor cost?

If dust settles on top of a radiant barrier, it becomes much less effective. Its ability to reflect radiation drops, and its emissivity increases in a negative way that increases undesirable heat flow.

Older methods of constructing a simple radiant barrier system (RBS) decades ago were nowhere as effective (functionally and cost wise) as modern new-construction zero-labor-cost RBS. Retrofitting a RBS into an existing home is labor intensive. It is so much better to include ZED from the ground up in all modern home construction, than to add it as an afterthought.

The well-engineered ZED radiant barrier thermal buffer zone greatly reduces (or eliminates) the need for expensive air conditioning systems in well-designed, passively-cooled Zero Energy Homes. On a conventional home a radiant barrier roof can reduce your air-conditioning bill by 12%. In a passively-cooled home (with cool tubes for solarium replacement air, or Earth buffering, etc.) the RBS is even more functionally effective. The (1 + 1 = 3) synergy of ZED integrated systems engineering can in many cases completely eliminate the need for electrical-compressor-based air conditioning systems in a modern Zero Energy Home, even in a warm humid Summer climate like Florida.

Storing Heat Energy in your Passive Solar Home

Solar designers use "thermal mass" to store excess daytime energy. The concept they use is that items with high thermal mass (like concrete, brick or water) must be incorporated into the holistic systems engineering to provide the desired “thermal lag."

Properly-designed, cost-effective "thermal mass" is essential to the success of Zero Energy Design® - especially in extreme hot-or-cold climates. Improperly designed thermal mass of the wrong type, in the wrong place (near glass, etc.), and poorly-insulated thermal mass can have a NEGATIVE impact on thermal lag and undesirable heat transfer.

Centuries ago, a large stone would be heated in an oven and then taken to bed to provide cozy early evening warmth. But, waking up later with a cold rock in bed with you was NOT a comfortable thing. (smile)

Well-meaning, modern designers have placed masonry walls or large containers of water in greenhouses to directly gain solar energy during the day, and radiate it back at night. Although this does improve the solarium performance by providing a desirable thermal lag in the early evening, it also produces high Delta T on cold nights across the southern glass wall (which has a low thermal resistance). The obvious (often ignored) result is a rapid thermal loss. (I think I would rather have a hot rock in bed with me . . . at least I could cover it up to reduce the heat loss a few hours later.)

Another problem with too much thermal mass is that it SLOWS DOWN THE WARMING PROCESS AT SUNRISE, when you want to warm your home as quickly as possible. Trombe Walls and water tubes are EXTREMELY BAD in this regard.

Some modern solar designers have tried to minimize the significant nighttime loss through the glass by using exotic, expensive, (sometimes ridiculous) items like bead walls, Freon-driven eyelids, and various automatic or manually-operated dampers, shutters and drapes. I have chosen not to give them any more space in this book, since they have no place in a properly-designed Zero Energy Home. The old HUD Survey of Passive Solar Buildings is full of all sorts of exotic, expensive experiments that failed to perform as their designers had hoped.

It is much more fun to learn from the errors of others, than to learn from our own expensive failures. This is the important difference between an energy research scientist, and a do-it-yourself home design experimenter.

Get More Information in Larry Hartweg's 850 page book on Zero Energy Design EBook or CD ROM .

Earth Sheltered Thermal Buffering (Part of Chapter 6)

Consider the use of insulated earth-sheltering berms to reduce conduction, convective wind chill, and radiant heat transmission loads on the building envelope. The use of earth berms, sod roofs or roof planting “green roofs” to essentially bury part of a building will minimize solar gain and wind-driven air infiltration. Earth sheltering will lessen thermal transfer caused by extremely high or low temperatures. They rely on the ambient temperature of the earth, which is much milder than seasonal temperature extremes.

Water resistant “Hycrete” is highly recommended. Moisture barriers, subsurface “French Drains” and surface water diversion are extremely important earth-sheltering design issues.

The energy requirement for such a beautiful Earth berm home will be the minimum possible. In the hottest climates, a cool tube, with downhill condensation drainage can be used for hot Summer days, but the properly developed Earth Berm will eliminate the need for a cool tube, since much of an Earth sheltered house is underground (depending on site characteristics).

2400 years ago, the ancient Greek city planners accurately determined that the most desirable place to locate buildings was the South / Southeast side of a hill (or mountain) with a nice view to the South (like the city of Priene). If you can find and afford such a near-perfect piece of real estate, consider yourself very lucky. A cut into the hillside, and an Earth berm buffer zone on the North (east and/or west side, and optionally an Earth covered roof with greenery) is a VERY ENERGY EFFICIENT, esthetically pleasing Zero Energy Home location.

Location-Specific Environment Requirement – Place-Based Design

All of ZED begins with a detailed understanding of the location-specific environment including: degree-day heating and cooling requirements, solar gain potential, latitude, elevation (sea level to mountains), seasonal weather / winds / cloud cover patterns, weather trends (e.g., Florida summer: Clear mornings with cloudy afternoons and frequent afternoon showers), site-specific desirable natural views, transportation requirements, available public utilities (if any), predictable growth trends (rising costs, future development, growth potential for the family / community / business), budget, funding source goals / objectives, building codes, political challenges, material supply, and any other pertinent planning details.

Your location’s seasonal heating and cooling requirements are of particular importance, since they have a major influence on the overall solution architecture that we will recommend.

American homes VARY WIDELY in their location-specific energy requirements, and solar energy potential. One ZED solution does NOT fit all, by any means. In general, the farther from the equator, the more heating requirement and the less available solar energy, but this is not always true. Climate is also impacted by altitude, mountains / valleys, prevailing winds, humidity / evaporation / cloud cover, albedo (surface reflection: white, black, green, etc.), heat index, wind chill, thermal mass, large bodies of water, oceans / lakes, cool trees versus hot concrete / asphalt, urban heat sources, nearby large buildings, smog and seasons.

One quantifiable scientific measure of location-specific design difference is the number of “Degree Days of Heating and Cooling Requirement” for a particular location. It has been gathered for decades by the national weather service, and is well published for about 300 diverse American locations – one of the close to you. The following is a partial list of only a small part of what is readily available. No reasonable home can be properly designed without this (and much more) information.


This is a primary NEVER-VIOLATE ZED MANDATE. It may look like a good solar energy thing to do (to a person who is clueless about ZED) but, Roof-angled glass is a huge heat loser on winter nights, when warm air rises to touch the low-thermal-resistance highly-conductive glass. It is also a huge heat gainer on hot sunny summer days. This is the plain and simple absolute scientific truth, often overlooked by those who should know better

Bad Roof Glass


These two stupid houses were costly failed experiments - by other Johnny-Come-Lately GREENWASH ARCHITECTS

Their arrogant non-learning architects thought they were wonderful BUT - They used more expensive energy than conventional houses It is expensive to remove the glass from the roof and then insulate.

In the summer, huge exhaust fans with fresh air intakes cannot possibly make a greenhouse with roof-angled glass cooler than the outside air temperature. However, in a ZED greenhouse, the peak interior greenhouse air temperature is much lower than the peak outside air temperature, by using intelligent design and NO ROOF-ANGLED GLASS EVER!

Roof-angled glass is often leaky, and is difficult to shade or insulate. When the huge expensive Houston Astrodome was first built, they quickly wound up painting the glass. Many important issues had been completely overlooked by the expensive (but clueless) architects. As the expensive special paint peeled off the glass, the roof became REALLY UGLY.

Condensation forms on the inside of roof angle glass on cold days, and especially winter nights. Roof angle glass with stuck-on leaves, grass, debris, or rained-on dust, dirt, mold, mildew or algae is UGLY and difficult to clean. Just look at the windshield of your car, if you leave it outside very long. The sticky stuff on the glass exterior builds up and becomes worse over time. Small twigs carried by the wind often get stuck in the glass mounting system. I’ve even seen a mis-delivered newspaper lodged on a glass roof. That really impresses your guests (negatively). Would YOU like to slide around on top of a large glass roof to do maintenance?

Bad Solar Design Bad Solar Design

STUPID, expensive, modern roof-angled glass architecture

Roof angle glass is at high risk of breaking in hailstorms, and possible heavy ice-and-snow loads in some northern locations. Rain and ice get caught uphill of a skylight mounting system, and can build up and expand underneath the roofing materials, causing leaks and rotting the surrounding roof decking. Water leak discoloration often forms below skylights on the ceiling, walls, or carpet. Large roof glass metal mounting systems can oxidize, rust, corrode and lose their paint over time – a real ugly maintenance headache.

Roof angle glass is ALWAYS BAD ON ANY BUILDING in any location. Roof angle glass is NEVER GOOD. New England settlers learned this important lesson hundreds of years ago by simple observation of poor thermal design, when every house was “off the grid” (no public utility companies back then). Old homes with roof angled glass simply did not survive for long. I can’t imagine why this dumb thing is happening today.

Plenty of cheery natural light can be designed into an intelligent modern Zero Energy Home using efficient vertical south-facing glass only. Even the most-northern rooms can make advantageous use of southern glass, using interior glass and mirrors – look at any of our ZED floor plans. We can easily accommodate artists who want diffused daylight, WITHOUT using north-facing roof-angled glass.

If you see a building with ANY roof-angled glass (skylights, domes, etc.) it’s clueless architect is BLIND, DUMB and COMPLETELY STUPID about the most critical issues of passive solar design, and ZED. Listen to NOTHING that such an idiot has to say about energy. If they have not discovered this foundational principle by now, they are a Non-Learning Entity with Zero Powers Of Observation. Let them experiment with someone else’s money, NOT YOURS.

Non-learning architects’ first experience with designing a passive solar house should be with their own home, so they will learn well the true price of ignoring the wisdom of others, and repeating the stupid mistakes that many have made before them, like roof angled glass. A few years of high winter night and summer day energy bills should be a memory they will never forget.

Get More Information in Larry Hartweg's 850 page book on Zero Energy Design EBook or CD ROM .

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