Green roofs, also called living or planted roofs, are systems of living plants and vegetation installed on the roof of an existing or new structure. The green roof concept is not new. The Hanging Gardens of Babylon constructed around 500 B.C. were perhaps one of the first green roof systems. Terrace structures were built over arched stone beams and waterproofed with layers of reeds and thick tar on which plants and trees were placed in soil.

Popular in Europe for decades, technology has improved upon the ancient systems, making green roofs available in and appropriate for nearly all climates and areas of the United States. All green roof systems consist of four basic components: a waterproofing layer, a drainage layer, a growing medium, and vegetation. Some green roofs also include root retention and irrigation systems, but these are not essential.

Green roof systems are often broken down into two types—extensive and intensive systems. An extensive system features low-lying plants such as succulents, mosses, and grasses. They require relatively thin layers of soil (1-6 inches), and plants usually produce a few inches of foliage. Extensive systems have less of an impact on the roof structure, weighing 10-50 pounds per square foot on average, and are generally accessible only for routine maintenance. Most residential applications are composed of extensive green roof systems. Intensive systems feature deeper soil and can support larger plants including crops, shrubs, and trees. Intensive systems can be harder to maintain, depending on the plants used, and are much heavier than extensive systems—they range from 80 to more than 120 pounds per square foot. Intensive systems are typically designed to be accessible to building inhabitants for relaxation and/or harvesting.

There is a wide variety of materials used for each component of the green roof system, depending on the chosen plants, type of system employed, climate, and underlying structure. Growing mediums include soils, peat and other organic materials, gravel, and other aggregates. A drainage layer is required to adequately distribute water and prevent pooling. To minimize the weight of the system, drainage layers are often made from plastic or rubber, but may also be made of gravel or clay. The drainage layer may or may not include filter media to ensure aeration. The waterproofing membrane is a critical component of the system and should include a root barrier to ensure the underlying roof surface is not compromised. If the weatherproofing material is not root-resistant, an additional layer must be applied to serve this purpose.

Plants used in green roof applications must be easy to maintain and tolerant of extreme weather conditions including heat, freezing, and drought, and must have relatively shallow, fibrous root systems. The plants should also be resistant to diseases and insects, and not generate airborne seeds in order to protect surrounding plantings. Climate-appropriate succulents, mosses, and grasses are often best suited for extensive green roof systems. These types of plants are available in a variety of colors, in both deciduous and evergreen options. Many nurseries throughout the country specialize in vegetation for green roofs.

(Lightning): The added mass and thermal resistance of green roofs reduces the heating and cooling loads of the building. These systems reduce the ambient temperature around the roof, decreasing the building’s urban heat island effect; reduce the ambient temperature of the roof’s surface; and slow the transfer of heat into the building, reducing cooling costs. They also provide added insulation to the roof structure, reducing heating requirements in the winter.

(Leaf): Green roofs reduce stormwater runoff by absorbing and retaining the water in the soil medium for plant growth. The plants can filter pollutants and carbon dioxide from the air and rainwater. These systems reduce rooftop temperatures and can reduce air and noise pollution. They also serve as living habitats for birds and other wildlife.

(Star): Vegetation protects the roof from extreme temperatures, ultraviolet radiation, and harsh weather conditions, resulting in a longer lasting roof system.

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Like insulating concrete forms for wall construction, ICFs for decks are reinforced stay-in-place polystyrene forms that become the structure of the floor or roof assembly when placed and filled with concrete. The forms provide an thermal resistance of approximately R-3.8 per inch, and provide sound attenuation once assembled. After shoring, bracing, and reinforcement are installed, 2” to 4” thick concrete is placed on top of the deck assembly. The concrete can be finished decoratively, and can include piping for hydronic or radiant heating systems.

Form shapes and method of installation vary between manufacturers. One manufacturer produces a two-foot wide foam panel by the overall span length, with integral steel joists that provide temporary support for the deck. Another manufacturer produces foam forms that measure 32” long x 24” wide x 12” thick, that rely on steel joists, spaced at 16” o.c. and purchased separately, for temporary deck support. However, most systems require temporary shoring of the deck.

The maximum span capability of the systems depends on the thickness of the form and concrete and placement of reinforcement. Span capability of ICF deck systems, under residential loading, ranges from 20 to 40 feet, depending on design and specifications. Some manufacturers supply forms that can also be used as temporary forms for precast concrete walls and decks.

(Lighting): ICF floors over unheated basements or crawl spaces will provide a well-insulated thermal barrier.

(Star): Reinforced concrete construction is an inherently permanent, fire-, termite-, and water-resistant material.

(Badge): ICF floor decks are water-resistant. They may provide a solution for decks on raised foundations where flooding can occur.
Many homeowners recognize the value of solar energy technologies but have been leery of the highly visible collectors on their roofs. Although the term "solar power" may be synonymous with environmental-friendliness and freedom from fossil fuel dependence, some types of solar systems have been avoided because of their unattractive (or unique) appearance from the curb. For this reason, photovoltaic (PV) modules,, which convert sunlight directly into electricity, have been integrated into roofing or other building materials as an alternative to traditional PV modules that are mounted above the roof on racks. The result is a photovoltaic system that is less noticeable but has benefits that are hard to miss. Once installed, BIPV components not only protect the home from storms and rainy weather but produce free electricity for use in the home. The residential industry most often uses building-integrated photovoltaic roofing products; however PV systems can also be integrated into façade materials, awnings, and covered walkways.

The many types of photovoltaic roofing products compliment many different roofing materials including asphalt shingles, standing seam metal roofing, and slate or concrete tiles. BIPV roofing products are produced by manufacturers whose products are designed to serve both functions -- as a roofing material to protect the home and as an electrical device to produce electricity. PV systems can be sized on a small scale to produce a limited amount of energy or be large enough to power an entire home and send excess electricity to the utility.

Most residential BIPV systems are used in conjunction with utility-supplied power. In addition to the PV-active roofing, an inverter, located near the electrical panel, converts the PV produced electricity into utility compatible alternating current (AC) electricity for the home. PV systems that utilize battery storage can produce electricity for the home even when the utility power is disconnected or when the sun is not shining.

Utility-provided electricity is used when the house demand is greater than can be supplied by the photovoltaic roofing. .PV systems can be sized on a small scale to produce a limited amount of energy or be large enough to power an entire home and send excess power produced during daylight hours back into the utility's lines. Typical residential PV systems commonly have a peak power production of between 1,200 and 5,000 watts, AC - requiring 150 to over 1000 square feet of roof area depending on the efficiency of the PV technology used.

(Lightning): PV systems reduce the amount of electricity purchased from the utility.

(Leaf): Electricity produced using the sun’s energy reduces the amount of energy used from non-renewable resources such as coal, gas, oil and nuclear, and energy is not wasted as transmission losses. In addition, there are significant environmental benefits resulting from reductions in air pollution from burning fossil fuels, reductions in water and land use from central generation plants, reductions in the storage of waste byproducts. In addition, the solar technologies produce energy with little noise and few moving parts.

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Walls, floors and roofs made of composite high density foam and stud panels Ray-Core Inc.®™ manufactures a patented Structural Insulated Panel (SIP) comprised of a high density polyurethane foam that is formed around pre-positioned wood or PVC studs with a radiant vapor barrier on both sides. These panels are used for walls, floors and roofs. The manufacturer states that the composite high density foam and stud panels are stronger than traditional wood and fiberglass construction and can cut heating and cooling costs by up to 50 percent.

The Ray-Core Building System combines foil-faced polyurethane foam panels with integrated wood or PVC studs into a 4' wide and up to 10' long lightweight highly insulated module. Top and bottom plates are dimensional 2x4 lumber and the skins are commonly an OSB exterior with a gypsum board interior that are installed on the job site by the builder.

Dimensional stability, rigidity, racking, creep and overall strength are provided by the foamed in-place studs placed 16" o.c. The manufacturer claims an R-value of 26 in the 3½" wall panel, and R-42 in the 5½" roof panel with 2" x 6" studs at 24 o.c.

(Lightning): Wall panels are rated at R-26 and roof panels are rated at R-42.

(Leaf): Factory panelization makes efficient use of resources and often reduces waste compared to site-built construction.

(Star): The panelized walls are dimensionally stable, rigid, strong, and provide resistance to racking forces.

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The SmartVent technology is a “total attic ventilation system” including components for ridge and eave vents. These components can also be used to easily ventilate other difficult to ventilate roof areas (e.g., dormer roofs, jack rafters at valleys, etc.). The product is a corrugated polyethylene plastic that comes with a synthetic fabric water guard to prevent bulk water and insect entry. SmartVent installs much like other roof venting products at the roof ridge. At the eaves, the SmartVent is installed on top of the roof (not under the soffit) and underneath the roof underlayment and cladding. It vents air from the drip edge through a gap in the roof sheathing. The product is about ¾” thick at the air entry (lower) edge, tapers to 1/8” thick at the top edge and is sized similarly to that of a standard composition roof shingle.

(Star): SmartVent can be used in new or existing construction applications to provide code compliant or improved roof ventilation. Excessive heat in the attic can result in decreased life expectancy of asphalt or composition shingle roofing, so shingle manufacturers recommend ventilation.

(Badge): Wind-driven rain that penetrates roof vents and damages home interiors is a source of property damage during hurricanes and severe storms. SmartVent provides an integral weather guard (synthetic fabric) that restricts bulk water movement through the vent.

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Harnessing energy from the sun to heat water is nothing new. Solar water heaters have been commercially available since the 1800s. What's new is how solar water heaters look these days. Most modern solar water heaters mount flush with a home's roof and resemble skylights. Solar water heaters are an environmentally sound way to reduce energy bills.

Solar energy can meet part or all of a home's domestic hot water needs. Geographic location, system design, collector orientation, and collector size will determine how much energy can be provided for domestic hot water heating. Solar water heaters come in a variety of configurations. Each differs in design, cost, performance, and level of complexity. Most systems have back-up water heating such as electricity or gas. A solar water heating system usually consists of a hot water storage tank, a solar collector that absorbs solar energy, a back-up energy source, and (for forced circulation systems) a pump and controls.

There are two main types of systems: passive and forced circulation. Within each type, there are several configurations. A passive water heater consists of a water tank integrated into or located above a solar collector. In an integrated collector storage (ICS) system, also called batch water heater, the water is heated and stored inside the collector. These systems are suitable only for warm climates where there is no risk of freezing. In a passive system where the storage is separate from the collector, as water in the collector warms, water flows by natural convection through the collector to the storage tank. A forced circulation system requires a pump to move water from the storage tank to the collector. Most solar water heaters in the United States are the forced circulation type.

There are several types of solar collectors. Most consist of a flat copper plate, painted black, that has water tubes attached to the absorber plate. As solar energy falls on the copper plate and is absorbed, the energy is transferred to water flowing in the tubes. The absorber plate is mounted in a casing that has a clear covering and insulation to protect the absorber plate from heat loss. Other collectors include an integrated collector and storage system and the evacuated tube collector. Integral collector and storage systems combine the function of hot water storage and solar energy collection into one unit. Evacuated tube collectors produce higher temperature water and are more complex than flat plate collectors. Evacuated tube collectors consist of a series of tubes that contain a heat pipe to absorb solar energy and transfer it to a liquid medium. The tubes are evacuated (vacuum) so that there is very little heat loss from the tube. Most solar collectors are roof-mounted. Solar water heaters are used for domestic hot water, pool heating and space heating needs.

(Lightning): Solar water heaters can help save on water heating costs by reducing the amount of gas and electricity needed to heat water.

(Leaf): By using sunlight to heat water instead of a combustible source or power plant-produced electricity, less pollutants are being introduced into the environment.

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Until the twenty-first century, most residential sloped roofs received a layer of asphalt-saturated felt building paper underneath the roofing material. Mimicking the attributes of housewraps, synthetic roof underlayments are now available to serve the same function as a secondary weather barrier with better resistance to tearing, moisture, and ultraviolet rays than traditional roofing felt. Synthetic underlayments are typically made from polypropylene, polyester, or fiberglass fabric which weighs less than felt building paper, can be manufactured with an anti-slip surface, and can withstand exposure to the elements for six months.

Recent natural disasters and subsequent rebuilding efforts highlighted the versatility of synthetics as roof underlayment by providing a real-life test environment. After several hurricanes ravaged southern coastal areas of the United States, many people were forced out of their damaged homes. At the same time, large numbers of homes required quick roof repair and "drying in" to minimize further damage due to water intrusion. With limited resources, contractors triaged homes, repairing the critical components and installing synthetic underlayments as temporary roofing. The underlayments performed better than FEMA’s blue tarps and didn’t require removal and discard when a roofing crew eventually arrived to install shingles.

One manufacturer offers a Class I fire-rated synthetic underlayment for roofs that require resistance to fire, as well as, the durable attributes of synthetic fabrics while the building is under construction.

(Star):Moisture resistance and hardiness make synthetic underlayment a good choice as a secondary weather resistant barrier under roof cladding.

(Badge): Polypropylene and similar synthetic materials resist moisture, tearing, and degradation from UV rays, making them a durable, relatively long-term covering that can be utilized for disaster response. Fire-rated synthetic underlayments can provide added protection against fire spreading through the roof in multi-family housing and/or regions of the country that are prone to wildfires.

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Many homeowners enjoy the natural lighting that skylights provide. However, skylights often do not distribute light evenly, are a significant source of energy loss, and can cause UV damage to carpets and furniture. Tubular skylights, on the other hand, use the sun for lighting interiors without the drawbacks associated with conventional skylights. They are generally easier to install than typical skylights and, from the home's interior, resemble conventional lighting fixtures.

Tubular skylights have a roof-mounted light collector typically consisting of an acrylic lens set in a metal frame. Most have a reflective sun scoop in the rooftop assembly that directs sunlight into a metal or plastic tube which has a highly reflective interior coating. The reflective tube guides the sunlight to a diffuser lens, mounted on the interior ceiling surface, that spreads light evenly throughout the room. The shape of the scoop is generally parabolic to reflect sunlight into the home regardless of the sun's angle in the sky.

Some tubular skylights have integrated electrical lights so the fixture can provide light both day and night and some have integrated baffles to regulate the amount of incoming sunlight.

The performance of tubular skylights varies widely between brands. Tests performed at the Alberta Research Council indicated that one 13-inch tubular skylight had equivalent light output of up to one 700-watt incandescent bulb in December and one 1,200-watt bulb in June.

(Dollar): Some of these systems cost less than conventional lighting systems, and most cost much less than a conventional skylight.

(Lightning): By utilizing the light from the sun during the day, considerable energy savings can be realized by not using electric lights. Energy savings attributed to tubular skylights will depend on the application.

(Star): Because tubular skylights fit between rafters or other structural elements and are lightweight, there typically does not need to be any modifications to a structure. Their simple design, complete with self-flashing kits, leads to their longevity.

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Roofing may include many different materials and techniques, yet it can greatly alter the appearance and energy efficiency of any structure. There are many materials that may help provide high quality roofing while minimizing its impact on the environment.

• Natural Slate
• Wood Shakes or shingles (FSC Certified)
• Fiber Cement
• Concrete
• Recycled content (typically made from recycled plastic and cellulose fibers, tires, and industrial rubber)
• EPDM (ethylene propylene diene monomer)
• Green or vegetated roof

• Provide a Light-colored or reflective roof
• Install radiant barriers on the underside of your roof
• Use your roof to harvest rainwater

If not insulated and weatherstripped, attic access covers can be a big source of energy loss for a home. Not only can conditioned air escape around the access panel’s perimeter, but uninsulated access hatches also facilitate heat gain and loss through the opening itself. Moisture-laden air from the house can condense on attic surfaces and deteriorate sheathing and insulation. To reduce energy loss and enhance a home’s durability, there are several prefabricated systems designed to insulate attic access hatches and to prevent drafts through them. In addition, there are many do-it-yourself methods and materials available for customized thermal sealing of attic openings. The various systems and methods for insulating and sealing the attic access utilize zippers, hinges, and an insulative box and cover. Several sizes are available from each manufacturer to fit different opening dimensions. Some attic stair units come with integral insulation for an all-in-one system that can be installed in one step.

(Dollar): Dependent on climate, cost of energy, and method used, attic access insulation systems can provide simple paybacks between one and ten years.

(Lightning): Estimates are that 250,000 Btus of energy can be lost through a two foot by four foot insulation void in the ceiling.

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Continuous attic air intake vents for rafter framed roofs The combination ventilation and drip edge system is an innovative approach to providing continuous attic air intake vents on homes with no eave overhangs. This type of vent remains hidden behind the gutter and does not detract from the architecture of the home. The use of ventilation and drip edge systems combines the steps of installing attic intake ventilation and drip edge, which directs rainwater flow from the roof into the gutter and saves installation time.

Roof and attic ventilation allows excess heat and moisture to escape from the home to reduce summertime cooling costs, pre-mature deterioration of roofing materials and moisture condensation that can lead to costly repairs. An effective attic ventilation system relies on natural convection to pull air into the attic from a low position, commonly through vents in a soffit, and exhaust heated attic air through a vent at a high position, such as through gable or ridge vents. Many new and existing homes do not have soffits, or their architectural style may not permit perforations in soffits for ventilation. Instead of sacrificing a proper ventilation system, builders and owners of these types of homes can install ventilation and drip-edge systems to improve the effectiveness of attic ventilation.

Ventilation and drip edge systems are made of either extruded vinyl or roll-formed aluminum and are manufactured in five or eight foot sections. They are designed to allow air into an attic or roof assembly from an inconspicuous location and simultaneously force roof runoff away from fascia boards and into the gutter. Manufacturers of ventilation and drip edge systems inform they work most effectively when installed in conjunction with exhaust vents located at or near the peak of a roof.

(Dollar): The system is relatively inexpensive and savings from improved efficiency can overshadow the cost.

(Lightning): By allowing natural ventilation to occur and help regulate temperature and moisture in the attic, heating and cooling loads due to the attic can be reduced.

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Many manufacturers now offer solar powered attic fans to ventilate attics and help keep attics cooler. Solar powered fans rely on a small (typically 10- or 20-watt) solar panel to power a DC motor when the sun is shining. The fans, which exhaust air at a rate of 800 to 1200 cfm, are installed with intake vents (such as soffit and gable vents) to provide high-capacity powered ventilation without electric operating costs. Most vents are mounted high on the roof, near the ridge, and combined with soffit or gable vents for balanced intake and exhaust air streams. Solar powered gable ventilators are also available.

(Dollar): Because they cost nothing to operate, solar attic fans are more affordable to operate than conventional powered attic fans. (Lightning): By reducing attic temperature, attic fans can help reduce summertime cooling loads while at the same time providing ventilation without added utility load.

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