Energy Efficiency

The wholesale price of propane increased at 3.8% per year from 1990 – 1999. That is the lowest annual increase we are likely to see given:

  • propane is tied to the price of petroleum and natural gas
  • petroleum prices have increased and are likely to be unstable, and storage facilities for petroleum, and especially propane are limited

Natural gas prices have increased sharply in the 1st part of this millennium because

  • natural gas is difficult and expensive to transport, especially overseas
  • the United States has over invested in natural gas as a fuel for power generation.

The embodied energy (that is the energy used to make the building) can equal 5- 20 years of the energy consumption of a building. That one reason is why we prefer to use fly ash. It is a waste product that replaces part of the Portland cement in concrete. Portland cement production requires strip mining limestone, crushing the limestone, and enormous amounts of energy to convert the limestone to cement. Fossil fumes are consumed and carbon dioxide is produced both by fuel combustion and limestone conversion.

Buildings are a major source of the pollution that causes urban air quality problems, and the pollutants that contribute to climate change. They account for 49 percent of sulfur dioxide emissions, 25 percent of nitrous oxide emissions, and 10 percent of particulate emissions, all of which damage urban air quality. Buildings produce 35 percent of the country’s carbon dioxide emissions the chief pollutant blamed for climate change.

There are many opportunities to make buildings cleaner. As just one example, if only 10 percent of homes in the U.S. used solar water-heating systems, we would avoid 8.4 million metric tons of carbon emissions each year.

Sun & Earth Construction uses quality materials with low embodied energy, while caring about the environment around us and building cost efficient homes.

Reasons for Choosing Energy-Efficient Design
  • Tangibles
    • Economics– the short term returns to building owner
      • immediate reduction in utility bills
      • decreased household maintenance, especially cleaning
      • increased appraisal without increase in property tax assessment
      • qualification for energy efficient mortgage programs
    • Economics – long term returns to building owner
      • energy costs increase more rapidly than inflation, so energy efficient upgrades increase their cost effectiveness. They appreciate more
        rapidly than other building amenities, which may even depreciate
      • energy efficient upgrades will be saving money at the same time they are appreciating. Similar to rental property except that they are a passive investment.
  • Intangibles
    • Human rights and political self determination
    • Sustaining the environment

“We are very pleased. The house has exceeded our expectations in terms of aesthetics, quality, and energy efficiency.”

Durability

The Foundation


We offer post tensioned concrete, using fly ash as an additive material to concrete.

The roof

The advantages of metal as a roofing material are efficiency and sustainability.
We combine these attributes and integrate this roofing into the heating and cooling system.
To learn more please go our Solar Systems page.

Radiant Floor Overview

Radiant heating systems convert a floor into a large area, low temperature radiator. Warm water is circulated through closely spaced plastic tubing that is embedded in the floor slab or attached to the underside of wooden subflooring. Underfloor insulation is a critical component. Zoning depends on advanced manifolds that regulate flow or modulate the water temperature in different tubing runs. Sophisticated controls regulate the system using temperature sensors in the slab in each room being heated as well as outdoors. [Read more]

Jim Graham, Las Cruces New Mexico Contractor

Economics & Weather

Las Cruces, New Mexico

Las Cruces is located in a high desert climate. The weather is characterized by low humidity and abundant sunshine. The low humidity and relatively high elevation contribute to the large temperature swings encountered during the year. The winter days are usually sunny and mild, with a substantial temperature drop at night.

The summer has hot days and cool nights with low humidity early in the summer, increasing in July and August. With the increase in population in Las Cruces and possibly influenced by global warming trends, both the humidity and ambient temperatures are slowly increasing.
Homes are heated predominately with natural gas in incorporated areas and propane outside of them. The most common heating systems are forced air systems without return-ducts and wall mounted heaters.

The most common cooling systems are evaporative (swamp) coolers, but the use of refrigerated air (air conditioning) is becoming more common. These systems usually use the same ductwork as the furnace uses in the winter. The ductwork is usually located in the ceiling or attic where it is subjected to extremes of temperature and where air leakage from the pressurized ductwork is lost from the building “envelope.” 20% loss of heating and cooling is not uncommon with these systems.

Evaporative coolers commonly use over 10,000 gallons of water yearly and require at least twice-yearly maintenance because of the sediments and salts left after the water has evaporated. Pads have to be replaced and the units themselves have a limited service life. Moderately large houses of 2400 sq ft typically require two coolers.

Refrigerated air systems, a.k.a. air conditioning, require less maintenance but have higher initial cost, typically $4000-$10000, and much higher energy costs, usually $300-$800 more per year on a moderately large house. However, electric generating stations consume a great deal of water, the additional use of which is invisible to the refrigerated air consumer while contributing to global warming.

The square footage cost was high compared to homes in this area, but that was due to high quality stucco, roofing, insulation and other features that have saved money over time.”

Weather Considerations
  • Elevation 3850 to 4500 ft
  • 32°19’ N Latitude
  • Winter Design Temp 20F
  • Extreme Low Temperature 10F
  • Heating Degree Days/year ca 4000
  • Comparison:
  • New York City ~ 7000
  • Minneapolis ~ 10000
  • Summer Design Temp 97F
  • Extreme High Temperature 112F
  • Cooling Degree Days/year ca 1000
  • Daily temperature range 26F
  • Average Cloudy Days/year 9
  • Clear Day Solar Energy Available in January: 1900 BTU/Square Foot/Day (A BTU is approximately the heat released by a burning wooden matchstick)
Radiant Heating and Cooling

We always integrate the domestic hot water system with an active solar space heater. Then the system can produce savings 12 months a year. In this area domestic hot water heating requires as much energy as space heating.

Jim Graham, Las Cruces Contractor

How Good is that Wall?

How Good is that Wall?

With a conventional 2 x 6 wall, you get a nominal R-19 rating, but the effective R- value is usually only a little over ½ of that due to heat transfer through wood components, voids around the wiring, and real world conditions.

Our minimum preferred framing system is a 2 x 4 wall with sprayed-in-place cellulose insulation backed with R-7 rigid foam insulation on the outside. The asphalt-impregnated paper facing on conventional fiberglass insulation is extremely flammable and difficult to extinguish once ignited. The cellulose insulation is a recycled product that is treated with borax and boric acid. Another example of green products having unexpected side benefits. Additional benefits are: reduced air infiltration, reduced cleaning, increased the usable area of the house and the overall measured external square footage, controlled insects and mold, and increased fire resistance.

We have also built frame walls with a nominal R-value of up to R-35, which is about what a straw bale wall is, but requires much less floor space. This gives an effective R-value close to R-27.

Almost 20% of the heat loss in a conventional building is due to air infiltration under frame walls. About 15% is due to heat loss through the opaque wall areas. Air leakage under the walls is a more important factor than the nominal R-value of the wall, but it requires more research, more attention by the builder, and it is much harder to put in an advertisement.

A typical house with 2 x 6 walls might have 120 less usable square feet than if it were built with our minimum framing system. It would have an appraised value area of 60-120 feet more. At $100 per square foot, that would be an $18,000 to $24,000 difference in your taxed property.

More important are the long-term ownership benefits. As an example, if a $10,000 investment in energy conservation saves $800 the first year and energy costs rise at 10% per year while housing values increase at 8% a year, at the end of the second year the energy savings will be $1,680, while the $10,000 investment will have appreciated to $11,800. After ten years, that $10,000 investment will have appreciated to $52,338. It will have saved $12,750 in energy costs. Also, the initial investment is typically part of a mortgage and may be tax-sheltered.

This does not count intangibles such as protecting the environment, preserving indigenous cultures from exploitation, providing a stronger economy, and having lived in a healthier home. Experience has shown that over time intangibles are often the most valuable and the most profitable. Economy and ecology have the same root word: oikos, which is Greek for house. What goes around comes around. We pay now or we pay later with interest, and the hidden charges are the ones that hurt the most.

Jim Graham, Las Cruces New Mexico builder

Types of Solar

Passive Solar Heating


Buildings designed for passive solar heating with natural sunlight to light a building’s interior incorporate large south-facing windows, skylights, and building materials that absorb and slowly release the sun’s heat. Incorporating passive solar designs can reduce heating bills as much as 50 percent. Passive solar designs can also include natural ventilation for cooling. Windows are an important aspect of passive solar design. In cold climates, south-facing windows designed to let the sun’s heat in while insulating against the cold are ideal. In hot and moderate climates, the strategy is to admit light while rejecting heat. Interior spaces requiring the most light, heat, and cooling are located along the south face of the building, with less used space to the north. Open floor plans allow more sun inside.

Active Solar Heating

Active solar heating systems consist of collectors that collect and absorb solar radiation and electric fans or pumps to transfer and distribute the solar heat in a fluid (liquid or air) from the collectors. They may have a storage system to provide heat when the sun is not shining.

An active system may offer more flexibility than a passive system in terms of siting and installation.

Heating your home with an active solar energy system can significantly reduce your fuel bills in the winter.

A solar heating system will also reduce the amount of air pollution and greenhouse gases that result from your use of fossil fuels such as oil, propane, and natural gas for heating or that may be used to generate the electricity that you use.

Combined Passive/Active Solar Heating

We have learned to combine passive and active solar elements in our designs because they both have advantages. Passive heating allows us to use building elements (walls, floors, etc.) as heat storage, reducing the requirements for water storage while leaving the advantages of active solar systems.

A cubic foot of water will transport or store 3800 times the amount of heat the same volume of air will. Active solar systems allow the use of water to collect, store and transport heat.

While some of our houses have been completely passive, actually able to meet their heating loads with the elegant simplicity of passive heating, we believe that a combined system is most effective because the increased area of glass amplifies total heating and cooling load, and active systems allow the greatest flexibility of site design, landscaping, and room layout.

One advantage to using the sun to heat your building in New Mexico is that it allows you to use the unique ”solar right of way” law preventing neighbors from shading your collecting surface, and preserving
the open spaces to the south of your building.

Sun and Earth are distributors of ezinc Solar Water Heaters. What better way to save money than to use the Sun to heat your water!

Other systems are available as well. We help you decide what’s best for you!

Jim Graham, Contractor/Builder Las Cruces New Mexico

Air Conditioning in Southern New Mexico

For the next issue, I would like to start an article on air conditioning systems that are commonly used in Southern New Mexico. We will begin with a brief explanation of how an evaporative cooler system works, how it can be improved and how it should be operated and the environmental costs of an air refrigeration system in comparison to an evaporative cooling system.

The evaporative cooling system works on the principle of evaporating water by drawing air through a moistened media. The media is typically either fibers of aspen or pleated paper. It requires about 7,000 BTU’s to evaporate one gallon of water. The amount of cooling you can achieve depends on how much air you can put through the cooler and how much water you can add to the air as it moves through it. The air coming into it with a lower humidity is going to absorb more water and will be cooled more thoroughly, so the temperature of the air coming out of the cooler is going to be lower than if you are working with outside air with a higher relative humidity. Evaporative coolers are much more effective in places like the Southwestern United States. But they also have limited use even in more humid areas for industrial applications.

There are several ways to improve efficiency on an evaporative cooler – to move more air with the same amount of electricity or to add more moisture to the air that’s being moved through it. The more modern evaporative coolers, which are sometimes called a single-pad cooler, such as the Master Cool Unit, are much more effective than the older, three- or four-pad units. They have a single pad that’s 8- to 12-inches thick in comparison to the older coolers whose pads are typically only an inch and a half thick. The pad on the Master Cool Unit only have to be replaced once every three to ten years in comparison to once or even twice a year with the older style evaporative coolers.

Two ways to make the coolers more efficient by moving more air are by having larger ductwork or shorter ductwork. A third way is to have a higher efficiency motor. The motors that are typically used on evaporative coolers are very low efficiency, shaded pole motors. It’s possible to put a higher efficiency motor on there that will have up to three times the efficiency of the more typical motors. The fan speed should always be adjusted by means of changing the diameter of the pulleys. They typically have an adjustable pulley to optimize the efficiency of the motor. This is done by using an ammeter. The ammeter is connected to leads outside of the air conditioner, and the air conditioner is run in its normal condition with all panels closed, pads in place, and vents open. Then the pulley speed is adjusted if the amperage reading does not agree with the amperage rating on the motor rating plate.

A properly sized duct for the evaporative cooler should be at least as large as the outlet of the evaporative cooler. Most commonly, evaporative coolers are hooked up to duct works that are sized for refrigeration or forced air heating. Efficiency can be increased by a factor of two-fold. Combine that with an adjusted, high-efficiency motor, and it’s possible to move up to six-times as much air for the same amount of electricity. In addition, the high-efficiency motor has a much greater life expectancy and doesn’t require any maintenance. The payback period on the high-efficiency motor is less than two years.

Lots of ductwork is in the attic where it picks up a lot of heat, and it is often poorly sealed so there is a lot of leakage. If the duct is insulated and sealed, it will improve efficiency or if the ductwork is moved inside the house or just greatly reduced in scope, you can improve the efficiency a lot. Much of the air distribution in a house by an evaporative cooler should be done by opening the windows in the part of the house that requires the most cooling. You can usually tell when you have enough windows open in the house because a piece of paper held up against a screen by the air pressure inside the house should barely stay on the screen. If it falls off, you have too many windows open and it’s stuck on hard, you need to have some more windows open. You should open the windows in the part of the house that’s hottest. It is not unusual for the air in the ductwork to vary from 5 to ten degrees in temperature from one end to the other. That’s quite a bit when you’re talking about the relatively small comfort range that people tolerate.

Evaporative coolers should have a bleed-off system or a purging system that removes part of the water to remove excess salt from building up in the water, which will cause corrosion. It’s very easy to move part of this water to landscaping. With a typical bleed-off system, you need 50 feet of quarter-inch black plastic tubing and two or three drip emitters and then periodically move those drip emitters around. If there is supplemental irrigation applied periodically, you’re not likely to cause any damage from excess buildup in the soil around the plants.

At the end of each cooling season, it’s important that the coolers be maintained. The ductwork connected to the evaporative cooler needs to be closed off very tightly. It’s common practice to put a canvas cover over a cooler, but it’s much more effective to close off the ductwork. Some coolers will have their warranty voided if you put a canvas cover over it. The theory being that you will build up moisture there during the winter. With the single pad units, you should put a pint or so of vinegar in it and circulate it for a half hour and then drain it.

All coolers should be hosed down at the end of the season and drained and the belt that drives the pulley should be loosened or taken off for the winter. In the springtime, the pads need to be cleaned and replaced
as needed, and all the bearings need to be lubricated. If there is any accumulated debris in the pans, they need to be washed out and the ductwork opened again. The air that comes out of the evaporative cooler eventually comes out of the house. It retains the entire cool that has been generated by evaporating the water. Ductwork registers cause a lot of airflow restriction, and substantial improvements can be made by using more and larger ducts, or by just eliminating them.

In contrast, a refrigeration system works by pumping heat from the inside of the building to the outside. A refrigeration system’s efficiency is based on how many BTU’s it can remove per watt of electricity uses. A typical refrigeration system has an efficiency rating of ten. The highest available right now is about sixteen. They are requiring an efficiency rating of twelve on new construction now. The maximum by how highly you can compress the cages that are used in it, and that is going to be limited by how high a temperature your systems can tolerate. I think we are probably reaching the limits of our efficiency already. The higher efficiency units are quite a bit more expensive than the standard units.

A substantial amount of energy that goes into a refrigeration-cooling unit is used to remove moisture from the air. The evaporator coils in a refrigeration unit are typically -20 to -40 degrees; so even in an arid climate, much of the moisture from the air will be precipitated out. This will increase the operating cost because you will have the same 7,000 BTU per gallon of water, but in this case, there is energy that has to be supplied to the unit to remove water from the air even though typically our air is dryer than we want it to be.

In a more humid climate, the de-humidification is a useful thing, but around here, it usually isn’t. In addition, this moisture will remain on the capillary coils when the unit is shut off, which encourages air-borne fungus, which releases spores, which causes health problems. The water that is extracted from the air is put into the sanitary drain where it has to be disposed of by the city sewer system. It causes an
incremental cost there before it goes into a septic system. The water that is being used in an evaporative cooling system actually cools off the immediate environment, whereas the refrigeration system heats and
dries the environment.

Commercial electric generation stations only deliver about one-third of the power that they consume as electricity to the end user. Most of the rest of it is waste heat. Most of the waste heat has to be eliminated
by evaporation of water, so electricity that is being used by refrigeration units requires the evaporation of a large amount of water be electrical generating units. It requires a gallon of water to generate one-kilowatt
hour. For the typical generating station that makes up most of our power supply, (here we will insert some figures about how much water is required for each unit of cooling the building requires, and how much power is in how many units of fossil fuel required for each cooling unit in the building.

Beating the Heat

From the El Paso Solar Energy Association:
The simplest way to keep cool is to first design and build your home for our unique climate, but that’s another article. For now we’ll concentrate on cooling an existing home.

If your goal is to keep a home cool in our desert climate, turning on the air conditioner or evaporative cooler is the LAST thing you should do. They’re expensive to operate, they use water and they’re noisy. There is no single answer to being comfortable but taking the shotgun approach is easier, and less expensive.

The three major sources of unwanted heat in your house during the summer are heat that conducts through your walls and ceiling from the outside, heat that is given off inside your house by lights and appliances, and sunlight that shines through windows.

Keeping the sun out of your home is obviously a major goal. Closing curtains and drapes makes your home darker but doesn’t effectively stop the heat. Stopping the sun’s energy from entering your home is best done on the outside of the window. Solar screens or shade cloth can stop as much as 80% of the sun’s heat before it enters your home. These materials are available at most home centers and window and screen suppliers. Windows on the west side are typically the biggest problem followed by the east and north facing windows. South facing windows are often protected by your roof overhang, which shades the glass when the sun is at its highest point. High-performance windows with “low-emissive” coatings (Low-E) and low “shading coefficients” will stop heat from the sun while allowing visible light to pass through the glass. These same windows help keep heat on the home during the winter.

Landscaping can play a large role in achieving comfort. Trees located on the west, east and north can not only put windows in shade, but also shade the walls of the home as well as the ground area. This shaded
area keeps the home cooler and cools breezes as the reach the home. On the south side, you should choose low growing shrubs and plants so as not to block the winter sun from entering south facing windows. This
vegetation will reduce the amount of solar energy, which is reflected
into windows by lighter colors.

The colors of various materials around your home can have a dramatic effect on your comfort and wallet. A dark colored roof can reach temperature 40 degrees hotter than a light colored reflective roof. This heat not only increases the cooling load of your home but also decreases the life of your shingles. Ventilate your attic space to reduce heat build-up during the summer, which finds its way into your home. Darker colored
walls especially brick and stone will actually absorb solar energy, which increases cooling problems and slows the nighttime cooling process. To reduce heat gains through walls and your ceiling, you can add insulation
and seal up cracks to reduce air infiltration.

You can reduce heat from lights and appliances by purchasing energy-efficient products. A conventional, incandescent light bulb uses only 10% of its input energy to produce light and the other 90% is wasted heat. Compact Fluorescent lights can produce the same amount of light as an incandescent lamp but use about one-fifth the energy and produce about one-fifth the heat. Check out the EPA’s Energy Star web site (www.energystar.gov) for energy smart options for your home.

Natural ventilation by opening windows is only effective when outdoor temperatures are lower than interior temperatures. An indoor/outdoor thermometer is a useful tool to determine the optimum time to open your windows. Open your windows when this temperature difference is reached in the evening and then close your windows in the morning. Opening windows more on the downwind side will increase airflow.

Evaporative Cooling

Opening windows is very important when operating an evaporative cooler. A common mistake in the El Paso area is not opening windows enough. If we think of an evaporative cooler as providing a nice breeze, then the best way to kill that breeze and its cooling effect is to close windows. You can increase the amount of cooling in one particular room simply by opening those windows more. The amount of force from an evaporative cooler is limited and can’t compete with a strong summer breeze/wind. If you have a 100-degree breeze coming from the west, then close those windows. When checking the operation of your cooler, make sure that the entire pad(s) is wet. Hot, outside air will flow freely through dry openings and dry pads drastically reducing the cooler’s effectiveness.

It’s very important to supply fresh water to an evaporative cooler and flush out the salts etc. left behind in the evaporation process. Typically this is accomplished with a bleed-off line but there is better, water saving method available at most home centers. Sometimes referred to as a “power dump” this new pump is installed in addition to your regular pump. This new pump operates on a timer and is designed to flush all the water in the pan once every 8 to 12 hours of operation.

The more attention you pay to the sun’s impact and the way you operate your home, the less you’ll spend while being more comfortable.

Don’t Forget your Ducts!

From the US Department of Energy:

Identify any leaks with diagnostic equipment. Seal your ducts with mastic, metal-backed tape, or aerosol sealant. Duct tape should not be used; it cannot withstand high temperatures and will not last. Test airflow after ducts are sealed. Your new or existing cooling and heating equipment is only as good as the system that carries its heated or cooled air. Central air conditioners, heat pumps and forced air furnaces rely on a system of ducts to circulate air throughout your home. To maintain comfort and good indoor air quality, it is important to have the proper balance between the air being supplied to each room and the air returning to your cooling and heating equipment. Leaky ducts can cause an unbalanced system that wastes energy. Sealing your ducts improves your system’s ability to consistently cool and heat every room in your home.

Duct Improvment Checklist

To improve your ducts, make sure to have your contractor:

  • Insulate your ducts where it counts to keep the air at its desired temperature as it moves through the system.
  • The contractor should use duct insulation material rated at R-6 to insulate ducts located in unconditioned spaces such as the attic.
  • Conduct a combustion safety test after ducts are sealed to be sure all gas or oil-burning appliances are working properly.

Green Building: Minimal Impact on Environment

A green building is any building that is sited, designed, constructed, operated, and maintained for the health and well-being of the occupants while minimizing impact on the environment.

Green building construction refers to those practices that promote occupant health and comfort while minimizing negative impacts on the environment. There are different degrees of “greenness.” Often it is necessary to strike a balance between many different sometimes conflicting “green” options based on the particular conditions of a given project. For example, proper strategy for a sustainable retrofit
project may differ from that of new construction design.

Green building practices offer an opportunity to create environmentally sound and resource-efficient buildings by using an integrated approach to design. Green buildings promote resource conservation by including design features, such as: energy efficiency, use of renewable energy, and water conservation.

By promoting resource conservation, green building design creates healthy and comfortable environments, reduces operation and maintenance costs, considers environmental impact of building construction and retrofit, and concentrates on waste minimization.

In the interim, green building design addresses such issues as historical preservation and access to public transportation and other community infrastructure systems. The entire life cycle of the building and its components is considered, as well as the economic and environmental impact and performance.

Jim Graham, Las Cruces Contractor

Post-Tensioning Concrete

Post-tensioning is a method of reinforcing (strengthening) concrete or other materials with high-strength steel strands or bars, typically referred to as tendons. Post-tensioning applications are commonly used in office and apartment buildings, parking structures, slabs-on-ground, bridges, sports stadiums, rock and soil anchors, and water-tanks. In many cases, post-tensioning allows construction that would otherwise be impossible due to either site constraints or architectural requirements.

In building construction, post-tensioning allows longer clear spans, thinner slabs, fewer beams and more slender, dramatic elements. Thinner slabs mean less concrete is required. In addition, it means a lower overall building height for the same floor-to-floor height.

Post-tensioning can thus allow a significant reduction in building weight versus a conventional concrete building with the same number of floors. This reduces the foundation load and can be a major advantage in seismic areas.

A lower building height can also translate to considerable savings in mechanical systems and façade costs.

Another advantage of post-tensioning is that beams and slabs can be continuous, i.e. a single beam can run continuously from one end of the building to the other. Structurally, this is much more efficient than having a beam that just goes from one column to the next.

Jim Graham, Las Cruces Builder

Metal Roofing

Metal roofs add energy efficiency and a reflective surface when natural metal or light colors are selected. They can enhance the look of your home and provide attic space/storage area.

A Metal Roof will increase the appraisal value of your home and last for years and years–far longer than a typical roof system. Aesthetically pleasing and energy efficient, metal roofs can be an enduring and attractive option.

High solar reflectance and high infrared emittance roofs incur surface temperatures that are only about 3°C (5°F) warmer than the ambient air temperature, while a dark absorptive roof exceeds the ambient air temperature upwards of 40°C (75°F).

In predominantly warm climates, the high solar reflectance and high infrared emittance roof drops the building’s air conditioning load and reduces peak energy demands on the utility. In North American climates, being predominantly cold, a more moderate reflectance and a low emittance result in a warmer exterior roof temperature, which reduces heat loss from the building.

Temperature, heat flow, reflectance, and emittance field data have been catalogued for a full 3 years for 12 different painted and unpainted metal roofs exposed to weathering on an outdoor test facility. Habitat homes were tested unoccupied for a full summer in Ft. Myers, Florida.

Measurements showed that the white reflective roofs reduced cooling energy consumption by 18-26% and peak demand by 28-35%. The houses were side-by-side, and had different roofing systems designed to reduce the
attic heat gain.

Results show that a judicious selection of the roof surface properties of reflectance and emittance represent the most significant energy and cost saving options available to homeowners and builders.

Superior Durability

Metal roofing is a proven product, more durable than most available roofing systems. Metal roofs simply last longer, and is often the roofing choice for many government, school and industrial buildings.

Excellent performance

Metal roofs rate high in wind, fire, and hail resistance.

Energy Efficient

Not only will a metal roof keep your house comfortable, regardless of the weather outside, it may actually lower your air conditioning and heating bills.

Environmentally Friendly

According to the National Association of Homebuilders Research Center, 20 billion pounds of asphalt shingles are dumped into US landfills every year. The recycled content of the steel in a metal roof is far superior to asphalt. Metal roofs also have a low per unit area weight, making it possible in most cases to install directly over existing roofs, saving removal and disposal costs.

Using Fly Ash to Improve Concrete Quality and Reduce Environmental Impact

Sustainable Construction For A New Millennia
www.sunandearth.net
Jim Graham Sun & Earth Construction LLC.

This article is about using fly ash to improve the quality of concrete while reducing its environmental impact. We are all concerned about the quality of Portland cement concrete used in our projects, and I hope also about reducing the environmental impacts of our built environment. There is a way to achieve both of these at the same time by the addition of fly ash to concrete.

Fly ash is a byproduct of the emission controls of coal fired power plants. Most fly ash is landfilled but can be recycled as an ingredient of concrete. It consists basically of tiny spheres of silica and is considered a “pozzolan” additive. Pozzolans are essentially inert fillers that take the place of much more reactive Portland cement and have been used since the Romans learned to make extremely durable concrete 2,000 years ago, even in aggressive marine environments. Portland cement production uses lots of energy and produces massive amounts of carbon dioxide.

Typically Fly Ash is used to replace 10-60% of the Portland cement in concrete. The effect on the concrete is to reduce shrinkage and reduce heat from the hydration of the more active Portland cement. It can lead to a much more durable concrete with less cracking and increased resistance to adverse reactions including Alkali Silica, chloride, and sulfates. It is widely used in highway construction, pre-casting plants, and dam construction. It is less widely used by residential concrete contractors, primarily as a minor hot weather additive to retard setting and reduce cracking, however it can be used in higher amounts and in cooler weather. The key to its successful use is by controlling the water/cement ratio, as are so many other aspects of good concrete.

There is often considerable resistance to fly ash use by trade contractors and even concrete producers. Let’s face it, construction is often very conservative about adopting “new” practices and there is a learning curve to fly ash adoption.

The most common concerns about using Fly Ash is that it will slow concrete setting time and will reduce high early strengths. These can both be addressed with water reducing additives. We can classify water reducers as standard or super plasticizers. Essentially their purpose is to make concrete more workable while using less water. Concrete use is often a conflict between more workability, which make the subs life easier, and a lower water to cement ratio, which does good things for the concrete and makes the engineer happy. Plasticizers can make everyone happier. So how do we use them, how much do they cost, and what is this about a learning curve?

Standard plasticizer is often included with regular concrete mixes, is added during batching at the plant, and shouldn’t have much effect on the cost. Superplasticizer can be added either at the batch plant or at the jobsite, is usually used at 40-90 0unces per yard, and might cost $.10/ounce. This incremental cost increase should be offset by the substituting of inexpensive fly ash for more expensive Portland cement.

Superplasticizer can be thought of as dehydrated water and is useful for other places in residential construction such as making concrete countertops and Portland based tile grouts on floors.

I would recommend learning to use superplasticizer in smaller projects at the jobsite such as sidewalks or driveway sections, before doing a large slab or foundation. The most challenging aspect of its use is probably timing. When used at the batch plant it may lose its effect by the time the concrete is placed. When added at the site it may delay setting time unacceptably. Avoid the temptation to add more water if it sets too soon and instead add more superplasticizer, which is a reason to keep some on the job, even when most of it is added at the plant. If setting is delayed it may be that the plant is adding too much water to improve mix ability and should add “super” early on. Properly used fly ash with super makes for a more workable concrete with higher early and ultimate strengths and improved pump-ability. Since fly ash is a recycled product it can be used to achieve points in LEED rating.

Hopefully this article on fly ash use in concrete will help you make better concrete while reducing its environmental impact.