Rutland Architectural Blog - greenConstruction

Wednesday, June 08, 2011

Buildings, including residential, commercial, public, and industrial consume about one third of all energy use and about two thirds of all the electricity generated. Demand for electricity in the U.S. is increasing three times faster than new power plants and lines are being built to accommodate this rapidly increasing demand. Heating and cooling costs dominate most building's energy usage. A building's roof can have the greatest impact on the energy consumption by a building so any technological advances and improvements in roofing energy efficiency and performance will greatly affect both energy usage and consequent cost savings. Energy efficiency, durability, performance, sustainability, recyclability and life cycle costs are the focus of green building. Architects, builders and consumers have been changing the way they select building materials and designing buildings. They are increasingly shifting their focus to green building materials and energy performance with so called cool roofs becoming a key focus. Cooling costs significantly affect a building's energy consumption in most parts of the country and cooling is the predominant cost in the southern states. Cool roofs can save up to 40% in cooling energy as reported by several studies including Lawrence Berkeley Laboratory Heat Island Group. Cool roofs essentially are roofs which reflect much of the sun's radiation away from a building, employ above sheathing ventilation (ASV) cooling under the roof, readily emit any heat which they do absorb back away from the building and cool quickly at night. The less solar radiation and heat entering a building's interior space through the building's roof, the lower the building's cooling costs and energy use will be.

Net Heat Flux Through Roof (courtesy coolmetalroofing.org)

Cool roofs or reflective roofs can be comprised of a variety of materials including asphalt or fiberglass shingles, clay or concrete tile, EDPM rubber or PVC roofing membrane and variety of metals as long as they can reflect away much of the sun's radiation and readily release any heat they absorb into the atmosphere. White and the more lightly colored roofing materials are the most reflective but different material composition as well as special designed and engineered coatings or paints used on them can also greatly affect reflectivity and emissivity. Some of these new coatings or paints, especially those applied to newer more advanced metal roofing, incorporate special pigments designed to provide higher reflectance of solar infrared and ultraviolet radiation. Infrared and ultraviolet radiation can contribute even more to absorbed heat energy from the sun than visible light so any type of roofing material incorporating these special reflective coatings may outperform conventional light colored materials without them. Even darker colored roofing which incorporates these special IR and UV reflective coatings will outperform older non treated darker colored roofing saving as much as 25% in cooling costs.

cool metal tile roofing shown having solar reflective coating cool roof and green roof energy saving properties

cool metal tile roofing shown having cool roof and green roof properties

Reflective Cool Metal Roofing Tile (courtesy coolmetalroofing.org)

Even with the advent of newer reflective coatings, white and light colored roofing still is the best performing cool roof providing the most energy and cost savings. Consumers, builders and architects however still like the aesthetics in having varied colors and materials and many still favor darker roofing hues. Ultra violet (UV) represents about 3% of the total solar energy striking the earth’s surface. Visible solar energy amounts to 40% while infrared (IR) energy accounts for the largest percentage 57% of the solar energy spectrum and is felt as heat. Thus roof materials which can be coated with newer UV and IR reflective coatings, even the darker shades of roof color, can now be much more energy efficient than in the past. Darker shades of roofing still won't reflect near as much of the visible solar radiation as lightly colored and white roofing. Though with engineered reflective coatings they will now block a high percentage of the UV and IR radiation which actually constitute more of the solar energy radiation and heat gain than visible solar energy. In addition to solar reflectivity, heat emissivity of roofing materials must also be considered as a large factor affecting building energy usage and possible contribution towards heat island effects. Any solar radiation which is not reflected by the roofing surface is then absorbed, converted or transferred to heat energy and some of this heat can conduct and radiate down into the interior building space affecting cooling costs. If the roof material has good emissivity much of this heat can re-radiate back to the sky in the form of IR energy especially cooling off during the night and there will consequently be less heat build up. Any concentrated heat build up, especially in tight grouped urban areas leads to heat island effects where temperatures in the air above these heat islands can be up to 12 degrees hotter than normal, leading to higher air conditioning costs, higher use of energy and higher levels of ozone and smog.

thermal image of Atlanta at night time showing warming heat island effects

Atlanta at Night Thermal (Blue=cool, green=lukewarm, red=warm, white=hot)

In addition to emphasizing high solar reflectance and emissivity properties, roofs can additionally be kept cooler, limiting or preventing heat gain or heat flux down into a building' interior space below, by promoting convection cooling underneath the roof material using above sheathing ventilation (ASV). Heat emanating from the underside of the roofing can be removed using convective air flow (balanced ventilation) moving from soffit vents or eaves up to and out a ventilating roof ridge cap. Testing at Oak Ridge National Laboratory showed that by employing the natural convection of heated air below the roof covering, temperatures in an attic space are reduced. Air enters at the eave, is heated by the roof, and because hot air rises, it is naturally drawn up and vents to the outside. This natural convection controls heat gain and reduces the temperature in the
attic below. The Oak Ridge National Laboratory study found that dark-colored metal-shingle roofs using above-sheathing ventilation had similar heat energy flows compared to their lighter cooler colored counterparts. About 30 percent of measured reduction in heat gain was contributed by ASV. When a cool reflective roof surface was used with ASV, an additional 15 percent reduction in heat gain was achieved for 45% total. The improved summer performance of cooler roofs coupled with the reduced heat losses during the winter show cool roofs can both reduce energy usage in summer months while negating any supposed heating penalty in cooler months or northern heating dominated climates.
* (see http://www.metalconstruction.org/pubs/pdf/ORNL-TM-2006-9.pdf)

A convective air space below the roofing material can be easily set up by using a batten, cross batten or metal purlin framework on top of roof sheathing or a roof deck, on which sturdy roofing panels can be attached. Less sturdy roofing material can employ a 1 1/2" metal roof deck or else just a purlin spaced layer of OSB below the existing roof sheathing. Even darker roof materials such as weathered bare copper which does not have a great solar reflectance index (SRI), can provide good to outstanding energy efficiency results with the use of either an underneath or above sheathing ventilation approach. Additionally winter or cold weather heating performance is improved with the use of below or above sheathing ventilation as that convection air space between the roof material and lower roof deck or sheathing further acts as an insulative layer and helps to prevent heat loss and condensation. Ventilated cooled roofs work great and are energy efficient in any climate. They tend to last much longer too with less heat degradation.

roof deck batten - cross batten construction framework shown on top of which cool roofing will be installed

Batten - Cross Batten Above Sheathing Ventilation (ASV)

roof structure cut out showing an energy saving cooling ventilated convection space positioned below the roof sheathing of a copper standing seam roof installation

ORNL Copper Roof Ventilation Test (images courtesy CDA at copper.org)
roof heat gain chart comparing different kinds of roofing including asphalt and cool metal roofing to a ventilated copper roof

roof heat gain chart comparing different kinds of roofing including asphalt and cool metal roofing to a ventilated copper roof

* These test results reflect using a 1½” fluted metal roof deck, ¾” OSB (plywood would work just as well), underlayment and red rosin paper underneath a standing seam copper roof. The use of a fluted metal roof deck is optional; similar results can be obtained by using other designs that provide an air space below the deck. The test roof had a 4/12 slope and faces south. The ventilated copper roof system was compared with a control roof of typical black asphalt, a typical non-ventilated copper roof assembly and two very good examples of above-the-sheathing, ventilated stone-coated steel roofs using special Cool Roof reflective coating colors. The graph above shows the ceiling heat flux crossing the attic floors of the respective attic assemblies. The light gray stone-coated cool metal roof (SR246E90) dropped the ceiling heat flux by roughly 29% of that measured for the asphalt shingle roof (SR093E89). The copper roof with the fluted metal deck further dropped peak ceiling heat flux an additional 23% of that for the coated steel shingle roof, bringing the total reduction for the copper roofing system to 50% of the asphalt control. Peak heat flux dropped an additional 1.5 Btu per hour per square foot for the copper roof as compared with the stone-coated metal roof. These results show clearly that a vented copper roof assembly will greatly reduce heat gain resulting in lower energy costs for the structure. Further, it dispels the notion that copper roofing must have high reflectance and emissivity in order to be effective in saving energy. * See Copper Roofs Are Cool

Cool roofs with their large energy saving and cost saving benefits can be realized by employing light colored roofing materials with very good solar reflective properties or roof materials using special engineered reflective coatings or most any type of roofing utilizing balanced and well functioning below or above sheathing ventilation (ASV). White or lightly colored highly solar reflective roofs employing ASV still provide the greatest energy and cost savings. It must also be stated that using higher R-values for ceiling insulation or better insulation below the roof in structures without attics will also control or limit heat gain into a building interior and consequently also lessens the heat gain differential using less reflective roofing materials or darker roof colors. Adding a radiant barrier and insulation board underneath your lower roof deck and convection space can further prevent the intrusion of heat gain from roofing into attic and living space. Additional attic vents, gable vents, dormer vents and roof vents will also reduce heat gain from roofing. More sloped roofs also perform much better and have less heat gain than flat or low sloped roofs and should be considered for any new construction. Some buildings with flat or low slope (<2:12) low-rise roofs may also be candidates for retrofitting them with a lightweight sloped roofing structure framework when re-roofing them especially with lighter weight roofing such as metal roofing. That framework could simultaneously also provide a convective roof cooling space underneath the new roofing. Resulting lower energy costs, less maintenance and no roof replacement for 50 years or longer could provide a good return on that investment. The bottom line is that when evaluating roofing energy efficiency, heating and cooling costs, looking only or primarily at roofing material properties such as SRI, reflectivity and emissivity is not sufficient to see the whole picture. You have to look at what effect the entire roofing system and structure has on heat gain, cooling load, heat loss and energy usage of the building and it's systems. The performance of the whole system must be examined in totality when the end goals are reducing energy costs and going still further, in achieving the most eco-friendly green buildings. In a subsequent blog article, the green building aspects of roofing will be discussed in more detail. Then again there are specialized roof systems such as KME's Tecu Solar System copper roofs below which are expressly designed as efficient solar heat collectors for heating a building's interior space, it's hot water and even swimming pool. Where do such technically advanced roofs fit into energy efficient roofing guidelines, requirements, ratings and green design certification?

copper roof integrated solar heating collection system shown in patinated green copper finish

Copper Solar System Roofs (photos courtesy KME.com - Italy)

copper roofing solar heating collector system for heating building and hot water system - shown in new raw copper finish

6/8/2011 8:55 AM Eastern Daylight Time

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Friday, July 23, 2010

Green Building Materials - Copper - Natural Stone

Copper and natural stone make ideal green building materials for both the exterior and interior of all buildings, including commercial, public and residential buildings. What is green building? Simply put green building means the construction, renovation or remodeling of houses, public and commercial buildings so they are more durable, environmentally responsible, energy efficient and healthier for their occupants throughout the building's lifespan or life cycle. This is basically accomplished by designing and constructing buildings that last a long time, are more efficient, use less energy and water and are healthier spaces to occupy and live in. Historically, well designed and constructed buildings have delivered short term goals of utility, economy, durability and comfort. Green building really just takes the next step in building even better homes, commercial and public buildings by improving on their long term durability, quality, efficiency, high performance, human health, environmental impact, life cycle cost and sustainability. A building's total life cycle cost includes it's design, siting, construction, operation, maintenance, repairs, replacements, renovation, deconstruction, salvage, disposal and recycling. Green building materials typically include: renewable plant materials such as quick growing straw, bamboo and wood from sustainably managed forests; materials which are non-toxic, reusable and recyclable such as dimension natural stone, recycled stone and recyclable metals. Eliminating construction materials and interior finishes which have emissions of toxic gases such as formaldehyde and VOC's improve a building's indoor air quality and is healthier for occupants. Moisture control and eliminating biological or organic sources of mold, bacteria, fungi and pathogens will also promote healthier air and living space. Implementing green building techniques reduces negative impact on human health and the environment during multiple phases including the production of building materials, building construction, occupation, building operation and maintenance of a green design building. While many green buildings cost a premium which averages just less than two percent initially, green building will typically yield a financial return or savings of over ten times that initial premium during the life of the building. Green building simply saves money, protects the environment and provides healthier living spaces. The strong case for green building is abundantly clear considering the positive impact on human health, our environment and our finances.

copper mining quarry in Chile pictured here

natural stone quarry shows dimensional stone from mined natural stone deposits in Beijing, China pictured here

Copper Mining Quarry and Natural Stone Quarry

Natural resources such as copper and natural stone are mined or quarried and minimally processed natural materials as opposed to artificially manufactured materials, faux or simulated materials. Pure copper and natural stone share many green building material qualities: they are mined or quarried directly from the earth and minimally processed using environmentally conscious techniques; all waste material can be used or recycled; they require no external finishes or chemical treatments; they generate no harmful emissions or byproducts; they do not promote growth of mold, germs or other harmful pathogens; they are healthy, hygienic and non-toxic; they promote more even indoor temperature and healthier indoor air quality; they are moisture and corrosion resistant; they weather extremely well naturally; they are not flammable materials; they are not damaged by water; they do not break down, decompose, decay or deteriorate like previously living organic materials and most man made materials; they age beautifully and gracefully as natural patina formation, discoloration, pitting, dents or cracks enhance character and natural appearance; they require little upkeep or maintenance; they are extremely durable, outlasting the owner's lifetime and the building's lifespan; they are salvageable, reusable, absolutely recyclable and retain their value extremely well. Copper and natural stone are two of the oldest, most durable building materials used by mankind and countless buildings and structures incorporating natural stone and copper architecture stood for centuries. Copper and natural stone were used because they were abundant resources found directly in the natural environment, required minimal processing and were fairly easy to work with. Today spending even a little more for natural, earth friendly, durable materials has proven cheaper in the long run because they won’t have to be replaced as often, maintained as much and can be recycled. Considering on building materials life-cycle cost, rather than focusing solely on initial cost can yield some eye opening results.

green building Sala at Penn State with Gold LEED certification pictured here

City Center building with Gold Leed certification in Las Vegas pictured here

LEED Gold Penn State SALA and City Center LEED Gold in Las Vegas

We spotlighted the Penn State Sala building above in a previous blog for it's heavy use of copper (over 80,000 pounds) helping it achieve it's U.S. Green Building Council Gold LEED certification and remarkably at no additional cost over conventional building. The recent City center in Las Vegas also received LEED Gold certification by the U.S. Green Building Council for six of it's buildings, including Aria, Vdara, Crystals, Mandarin Oriental, Las Vegas and Veer Towers. That made City Center one of the largest sustainable green building developments in the entire world. The immense project entailed collaborative involvement by eight renowned architecture firms. Green building material selection, included extensive use of natural stone for interior spaces and exteriors of the buildings. While other green materials were considered, natural stone provided the architecture with a natural textured, tactile feel and the richness, warmth, comfort, earthy look and colors they sought. The Aria building encompasses 70,000 square feet of natural quartzite stone cladding in a varying thickness mosaic pattern on it's exterior walls. Inside the buildings, different uses of natural stone were employed including a mosaic stone, stacked stone, flat honed or polished stone, to provide contrasting looks and changes in texture. Everyone involved with the project was happy with the results and the buildings continue to garner positive feedback and compliments. See additional pictures of City Center and information on it's green building features in the Stone World article Stone Contributes to LEED Certification for New Las Vegas Landmark

architectural copper work and natural stone masonry on home pictured here

natural stone wall cladding and copper gutters on house pictured here

Architectural Copper Work and Natural Stone Wall Masonry

View additional natural stone pictures of genuine natural stone installations at the Rutland Minstone website, encompassing natural stone tile flooring, natural stone walls, natural stone patios, garden stone paving, landscaping, slate roofs and stone columns. Slate, travertine, quartzite, limestone, sandstone and flagstone tiles, wall veneer panels and pavers are some of the featured natural stone applications. With large advances in mining, processing and shipping technology, use of natural stone has grown from use primarily only in major buildings and large expensive estates to becoming a staple in homes and buildings of every size and budget today. There has been a drastic reduction of genuine stone prices over the last decade or so. Around the world there is now an enormous inventory of natural stone and even more is being discovered every day. A combination of many technological advances and this very plentiful supply have combined to make natural stone very affordable and price competitive with man made materials, while having better green building characteristics and life cycle cost benefits. People have embraced the beauty and elegance of this unique, all natural material for their floors, wall coverings, kitchens, baths, outdoor landscaping and paving. Consumers prefer natural stone because it is the real thing which can not be duplicated in a laboratory or factory but is nature's very own genuine product. Natural stone is created by nature in many thousands of color variations with no two natural stone pieces exactly the same. Nothing approaches the uniqueness, durability, wide applicability of genuine natural stone and pure copper. From the beginning of time to far into the future, copper and natural stone have always been excellent green building materials while having natural beauty, grace, warm richness and timeless elegance.

7/23/2010 9:06 AM Eastern Daylight Time

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Wednesday, December 16, 2009

LEED Certification Green Building

LEED or Leadership in Energy and Environment Design is a third party certification and building rating program for building performance across several key areas. LEED attempts to measure a building's performance and sustainability across such areas as: optimizing energy efficiency as well as use of renewable energy; efficient and sustainable use of building materials and resources, including reuse, renewability, recycling and durability; innovation of design, incorporation of high recycled and regional content; water conservation; ensuring infrastructure and limiting neighborhood and environmental site impact; indoor air and environmental quality, including occupant comfort; reduction in CO2 emissions; efficient operation with low or reduced maintenance and energy costs. Developed by the U.S. Green Building Council (USGBC), LEED is a voluntary certification which strives to verify and promote sustainable high performance buildings or communities with less environmental impact, improved livability and long term savings. While LEED is still evolving, incomplete and not nearly perfect, building rating systems, certification and verification are raising our awareness and expectations for building performance and helping shift the construction market and demand toward healthy sustainable building, our long-term well-being and environmental responsibility.

copper cladding exterior walls are recycled from regional sources in Penn State's SALA green building shown here

Penn State SALA Building - Recycled Copper Cladding

Copper used in green building materials and strategic building components contributes to high environmental and building performance in many areas, most of which qualify for credits towards LEED certification of a building. For example Pennsylvania State University's School of Architecture and Landscape Architecture (SALA) used over 80,000 lbs (35,000 kgs) of copper in its construction and it was the first building to achieve a gold LEED certification at no additional cost. Most noticeable is the pre-patinated, 95% recycled copper cladding used for the exterior walls as shown above. This green building project used copper extensively for copper's green properties: high recycled content; local or regional availability; durability; high rate of recyclability at end of building's useful life; low or non-existent maintenance costs for copper; workability of copper. To maximize these benefits, in addition to wall cladding, copper was used for all soffits, sun shading and even on ceilings of large atriums. Looking at long term cost factors also ensured copper's prominent role in this green building project. Copper's legendary durability is measured in generations rather than years or decades with little to no maintenance required throughout it's lifetime. Virtually 100% of the copper can be recycled upon eventual demolition or replacement of the building and recycled copper maintains 95% of the value for new mined copper. Copper also has the best heat and electrical conductive properties of any viable metal as well as superior resistance to corrosion. Copper's many attributes are reflected in copper's contribution to green building high performance with 13 possible LEED credits across 3 performance areas. Copper's aesthetic qualities also ensure green building architects achieve attractive, visually appealing green LEED designs without sacrificing any efficiency, performance or environmental objectives.