Do buildings designed for high performance function as intended?  Do energy savings, improved occupants’ productivity and comfort materialize as promised?  Green buildings offer a lot of benefits, but building owners and tenants increasingly want proof that these benefits are actually achieved.

This is where post-occupancy evaluation (POE) comes in.  The objective of POE is to learn whether the building is performing as designed and whether it meets the occupants’ needs as intended.

POE originated in the 1960s, as a part of a movement to apply scientific approach to architecture and to explore the new-found connection between behavioral sciences and design.  Designers saw POE as a tool to test their hypotheses as they tried to use design to change people’s behavior and relationship with the built environment.  It was used to evaluate building systems as well as occupants’ responses to those systems.  After the peak of popularity in the 1970s and early ’80s, the use of POE declined, until the sustainability movement reclaimed it.  Today, building owners rather than building designers are driving POE.  For a building owner it is one thing to read in a study that green buildings on average perform 25-30% better, or that they command higher rents and occupancy rates, but it is another to be able to verify that their own building does so.

At the same time, growing popularity of building ratings, as well as the increase in local and state disclosure ordinances requiring building owners to publicly disclose actual energy consumption, makes POE almost a necessity.

This means that there will be pressure on building designers to incorporate features that will allow building owners to operate the building to design specifications.  Buildings will need to have feedback systems to help facility managers and occupants understand how their choices affect the building’s performance.  In this task, “smart” buildings have an enormous potential, as they can use the data they are constantly generating to engage users’ by providing real-time, visually appealing and easy to understand performance feedback via dashboards.

The classic POE involves surveys, targeted interviews, focus groups, and direct observation of the building and its occupants.

POE of the occupants’ comfort typically focuses on the work environment, elements such as lighting, acoustics, thermal comfort, privacy, and convenience.  POE of the building performance, also called “building performance evaluation”, focuses on energy and water use, and even financial performance.  In “smart” buildings, POE will include quantitative testing and measurements of building conditions, such as illuminance and temperature.  Depending on the interests and needs of the building owner, other sources of information, such as utility bills, maintenance records, and financial statements, might also be analyzed.

POE can range from one person walking through with a notepad and doing some interviews, to a team of environmental psychologists, sociologists, cultural anthropologists, architects, and engineers collecting data and conducting in-depth focus groups and extensive surveys.

Usually, POE is undertaken after the building systems are commissioned and fine-tuned so that occupant reactions are not distracted by technical problems with equipment.  However, it might also be beneficial to use POE-style occupant surveys as a part of a commissioning process.

LEED and POE

Green and high-performance buildings are especially good candidates for POE, as it allows to document the results of using innovative technologies and materials that might so far have limited or no track record.

POE creates hard evidence that green building advocates can use to make their case to skeptical clients, owners, investors, or tenants.  With data on the table, the conversations evolves from the argument that “this is the right thing to do” to using facts to demonstrate how green design meets clients’ financial or other critical interests.

POE is an important tool for supporting the LEED rating system.  Many of LEED requirements are normative, that is, they are based on theory, but largely haven’t yet been validated by practice.  There is a lot of interest in seeing whether LEED-certified and other green buildings really deliver on their promises.

The 2012 update to LEED has a newly created “Performance” category which includes two LEED credits: “Reconcile Projected and Actual Energy Performance” and “Occupant Experience Survey”.  This development shows that, as the green building market matures, LEED guidelines adjust accordingly.  LEED seeks to serve both the energy reduction goals and occupants’ comfort and wellbeing.  In this, POE has become a valuable tool which allows to measure satisfaction and integrate occupant comfort with energy performance.

The rating system that is currently best suited to incorporate POE is LEED for Existing Building Operations and Maintenance (LEED-EBOM)

LEED-EBOM (Existing Buildings – Operations and Maintenance)

LEED-EBOM is the fastest growing of the LEED Rating System.  It sets performance standards for the operation of existing buildings that are not undergoing major renovations.  It is different from the other LEED rating systems in that it documents the actual building performance, rather than an estimated performance based on design.

The first time the building goes through the certification is called the initial certification.  The initial certification happens in two phases:

1. Establishment period – assess the building, do cost-benefit analysis, select credits to pursue
2. Performance Period (PP) – implement new policies and building changes, as well as track ongoing building performance.

All buildings, even those that were LEED-certified for Design and Construction, must go through the initial certification.

A successful LEED-EBOM certification requires a collaboration from a variety of stakeholders: building owners, property and facility managers, general contractors, vendors and tenants.  This team will set up policies, procedures and targets to achieve for the certification.  This process is normally facilitated by a LEED AP specializing in EBOM.

LEED-EBOM is also the only LEED rating system that requires re-certification.  Re-certification verifies that the building has been operated and maintained in accordance with the standards achieved during the initial certification, or, ideally, that its performance has improved over time.  Buildings must get re-certified at least every 5 years, although more frequent re-certification is encouraged.  Once a building receives the initial EBOM certification, the re-certification process begins.  There is no fee to re-certify, and it should be fairly easy, since all the policies and procedures are already in place.  During the re-certification, a building performance evaluation is conducted in the form of audits, surveys and testing to track the on-going performance of policies established during the initial certification.  This evaluation may open up the opportunity to increase the building’s certification level.

Looking into the future: LEED and POE

Benefits of POE work well with the priorities of green buildings.  In the short term, POE can suggest adjustments to improve performance and occupants’ experience.  In the long term, designers and their clients can use the feedback to improve the design of subsequent projects.

As the performance evaluation tools are perfected and commoditized, they will inevitably become more widely used.  When they are more widely used, the great flow of information will serve to improve our understanding of how buildings work.  Incorporating POE into LEED will help to ascertain that our buildings are serving their intended functions.  Shouldn’t that be a prerequisite for green buildings?

In some cases, however, building owners purchase or manage facilities built before the 1980s. With these buildings, there is a good probability that asbestos products such as drywall, insulation and tiles are present. Owners then face special challenges when having construction work done on their buildings.

Before hiring renovation crews for potentially asbestos-disturbing tasks, these building managers are required to perform asbestos inspections. Federal regulations mandate these surveys for all public schools and most government buildings, as well as for all older buildings that are set for demolition or renovation. By identifying and acting on any potential hazards, owners can avoid Clean Air Act violations and major risks to their workers’ health.

Non-Construction Related Asbestos Management Surveys

Property owners not planning construction in the near future can conduct these surveys on their own schedule – or not at all. However, even when asbestos management surveys are optional, owners should still consider regular testing. This simple process is a major step in protecting the general health and well-being of the building’s occupants.

If asbestos is present and friable (loose), the building’s occupants are at risk for a number of serious conditions, including mesothelioma and lung cancer. Initial prognosis for someone exposed to asbestos, may not come for 30- 50 years. During this latency period, anyone who inhaled asbestos may develop these illnesses at any time. Asbestos management is one of the only proven ways to help prevent people from developing these conditions.

Surveys help building owners identify all the asbestos-containing materials on their property, then determine which ones are imminent health hazards. Inspectors also can provide suggestions for remedial action for these products; in most cases, owners can choose between removal and encapsulation. The inspection crews can make recommendations based on the location and condition of the asbestos-containing materials.

Additionally, asbestos surveys provide documentation of non-friable asbestos products that may become a threat in the future. If the property was to change hands, these surveys can help the future owners make environmentally conscious construction decisions.

Scheduling Asbestos Surveys

Before scheduling an asbestos management survey, building owners should check the credentials of the company they plan to hire. The surveys should only be done by accredited asbestos management companies, and all inspectors should have up-to-date licenses.

Owners should evacuate the building during the survey, since inspectors may take samples of the fibers. To provide the most accurate results, surveyors should review the following details before the survey:

• Site layout
• Building specifications
• Future building plans
• Past asbestos inspection history

Depending on the type of asbestos and its condition, surveyors should inspect an asbestos-containing building every six to 12 months. If any construction work occurs, inspectors should perform another follow-up inspection to ensure the safety of the building’s residents. The diseases, such as pleural mesothelioma, that can arise from asbestos exposure are serious; therefore all precautions should be taken to prevent such exposure.

Every house is unique and foundation-type is one distinct difference between them.  A home typically has a crawl space, basement or a concrete slab foundation.  In this three part article series author Joe Provey explains how foundation-type should be taken into consideration when upgrading a home’s energy efficiency. Joe’s first article explains how a home with a crawl space foundation can increase their energy efficiency.

 
Save energy with the bonus of controlling excess humidity and improving home air quality!

Like it or not, your crawl space and living space are joined at the hip. Holes for wiring and pipes, plumbing chases, leaky heating ducts, gaps in subflooring, ensure that your living space and your crawl space communicate freely! It is no surprise that the U.S. Department of Energy recommends you insulate your crawl space. Insulation in the floor joists is typically inadequate to offer much of a barrier. To make matters worse, the laws of physics actually cause the air in your crawl space to be pulled up into your living areas. As warm air rises in the upper levels of your home, it creates a draw on the lower areas. As much as 40 percent of the air in your crawl space eventually mixes with the air inside your home.

This creates a whole series of problems, ranging from energy loss to breathing unhealthy air. In summer, cool air is lost to the crawl space. In addition, excess humidity from the crawl space causes your air conditioner to work harder and use more electricity than it should. In winter, cold air entering through the crawl space makes your floors cold and first level rooms drafty. Heating bills climb. Winter and summer, you’re apt to be breathing unhealthy air laden with allergens and soil gases.

There are five steps you can take to turn a crawl space into a clean, healthy, energy-efficient part of your home. Here they are roughly in the order you should tackle them:

1. Seal and insulate rim joists
The first framing member attached to a foundation is called the sill plate. It lays flat atop the home’s foundation wall and is fastened to it with J-bolts or by some other mechanical means. Because the top of the foundation is often uneven, there may be gaps under the plate. In new construction, a gasket helps to solve this problem, but in older homes it is a major cause of air leakage. The second framing member is the rim joist. It rests on edge upon the sill plate and provides a way to secure floor joists. Subflooring is installed over the rim and floor joists. Air leakage may occur at the joints between the sill plate and rim joist as well as between the rim joist and subfloor. In addition, the R value of the rim joist (its ability to stop conductive heat loss) is only 1.88 – about the R value of a single pane window with a storm window in place.

To stop energy loss from the framing assembly that rests upon your foundation wall, seal all joints with a bead of closed-cell foam insulation. Then install rigid foam board insulation against the rim joists wherever possible. For example, cut the board insulation to snuggly fit between the floor joists and between the sill plate and subfloor. Then press it against the rim joists. If the fit is loose, fill the gaps with spray foam insulation.

2. Seal ducts that run through crawl space

Heating and cooling ducts often reside in the crawl space. Typically fabricated from sheet metal, they’re used to distribute warm or cool air to the rooms of your home. Unfortunately, ducts typically leak a large percent of the air they carry. This means your HVAC equipment must work overtime and that your energy bills are higher than they need to be.

To stop energy loss from ducts, seal all metal-to-metal joints and holes with mastic sealant or with metal tape. Do not use duct tape because it will eventually fail. Seal joints between the subfloor and ducts with spray foam insulation. If you do not plan on insulating the walls of your crawl space, consider insulating the ducts with duct wrap. Duct wrap is fiberglass product with a foil vapor barrier to the outside. Be sure to seal all seams with aluminum duct tape. Otherwise, air leaks will allow moist air to penetrate the wrap. In summer, that moisture is likely to condense on the cooler ducts and wet the fiberglass – and wet fiberglass is ineffective as an insulator.

3. Insulate walls

The above- and below-grade portions of your crawl space wall will lose heat in winter, so you will save energy and be more comfortable by installing wall insulation. Rigid foam boards can be adhered to or mechanically fastened to either block, stone or concrete walls. They are waterproof and will not support the growth of mold. The recommended R value depends upon where you live. Check with D.O.E. recommendations or with local building department officials for recommendations in your area.

4. Encapsulate

A continuous vapor barrier that covers both floor and walls adds another layer of insulation by sealing out air leaks. It will also help control moisture and stop soil gases from infiltrating your home. For a vapor barrier to be effective in the long term, it must be durable. If interested in taking on this project yourself I recommend this great guide that explains how to install a vapor barrier.

If your crawl space is susceptible to water infiltration, install drainage matting before installing any liner. It will allow water to drain toward either a drainage pit (no pump) or to a sump basin and sump pump for discharge. Here is a great resource explaining in detail what needs to be done to fix crawl space water leaks.

5. Dehumidify

If you’ve opted for encapsulation, install a dehumidifier in your crawl space to dry out framing and flooring that has long been exposed to excess humidity as well as to ensure against excess humidity on an ongoing basis. Lower humidity in your newly conditioned crawl space will translate to lower cooling costs and greater comfort in warm weather.

An investment in any or all of the above will make your home more energy efficient and improve the comfort level and health of family members. In addition, controlling moisture levels protects your home from structural damage due to rot, corrosion, termite infestation and can give your home extra storage space.

Interested in learning more about crawl spaces? This very informative crawl space learning center can educate you on this often overlooked part of a home.

Have any other tips to help make your crawl space more energy efficient? I would love to hear about them in the comments below!

“In the day”, I was sent to Siemens Photovoltaic Cell manufacturing plant in Santa Barbara to visit with the Southern California Edison customer, document the manufacturing process and take some pictures for my bosses presentation.  It has been years since then and the United States, the once leader in cell manufacturing, has given way to others overseas (~four(4) cell manufacturers remain in U.S.).  As a result, a manufacturing goal of 100% “Made in the United States” cannot be achieved for photovoltaic (PV) modules with mono-crystalline cells at cost effective prices.  Never the less, other quantifiable goals like USGBC LEED Material Resource Credits can be achieved.

Various products can claim to be as much as 80% made in the United States and anywhere from $1.80 to $4.50/Watt installed (including but not limited to, additional structural systems like; racking, ballast, lagging or wood lattice).  Using a goal to be the “Greenest” possible without additional expense, the owners of EcoGym Worldwide set out to design a PV System that met some of these goals.  Seeking the guidance of A Solar Studio, a small 2-3 man studio in Naperville who’s principal has been involved with PV off and on for the past twenty years, they learned they could achieve some of these goals using the Solon Sol quick 295.

Ecogym’s solar renewable system was designed for a flat roof commercial tenant space approximately 10,000 square feet, few obstructions in the roof, 5 air handling units and a 4′-6″ south facing parapet.  The system is is expected to produce 7.93 kW of AC power  each solar hour per day and has been designed for a future second phase development if needed.  Yellowlite, Inc., a regional solar installer located in Cleveland, Ohio was selected as general contractor and installer.  Solon Corporation is a subsidiary of Solon Group located in Tucson, AZ provided the modules for the system.

The Solon Solquick 295 module is largely manufactured in the United States. The critical monolithic rack (perhaps 60% by weight) is made in Minnesota where it is then shipped to Arizona for assembly and testing prior to shipment.  They are a fixed tilt (~9°), ballasted, non framed rack.  The 295W modules are connected in series and provide designers with a low profile tilt thereby reducing wind loads significantly and with no snow drift issues caused by the array.  In addition to the interconnection ties and cinder blocks used for ballasting, the A Solar Studio design team required an additional 5 positive connections on both the east and west sides of the arrays.  These connections are lagged through the roof reducing uplift most prominent in the winter months of northern Illinois.

The net metering process was very simple by comparison to other utilities in the northern Illinois area. The City of Naperville has its own municipal utility where it gets a large portion of its electricity from renewable resources west of the community in the form of wind turbines. Its net metering process consists of a one (1) sheet application submitted at the time of permitting with no other communication exchanges needed unless a copy of the application is not available on-site when final inspection is conducted.

A look at today’s architecture and design magazines, or at new construction projects in NYC, confirms that the current material of choice is glass.  Floor-to-ceiling windows, 360° views, natural daylight, connecting inside to the outside are the design vocabulary du jour.  Glass, and lots of it, is intended to convey modernity, sophistication, and, increasingly, green design.

The first glass was made about 2,000 years ago.  It was used to seal off small apertures made to let in light.  However, it was not until many centuries later that the use of glass in buildings became widespread.  Still, window sizes were constrained by practical considerations: impact on the load-bearing capacity of the walls, material limitations, energy conservation requirements, expense.  In the 20^th century, the development of structural steel, and later reinforced concrete, allowed to transfer bearing loads from the exterior walls to interior columns.  At the same time, glass came in increasingly bigger unbroken sheets.

The International Style in architecture, made simple glass façades and huge opens spaces synonymous with modernity.  In the late 1940s, double-pane glass with thermal insulation was created.  Windows were becoming bigger and bigger, until eventually the entire exterior skin of a building was made of glass – it was called the curtain-wall.  Lever House, built in 1952, was the first curtain-wall building in New York.  By 1970s, coated, laminated glass, and other innovative glass products were created.  Today, fully-glazed office buildings are ubiquitous, and in residential buildings, especially on the higher end, panoramic, huge, often floor-to-ceiling windows became a requisite amenity.

What is it that makes glass so appealing to architects and building owners? 

Aesthetics: A successfully designed glass building looks sleek, simple and modern.  It is in harmony with the environment.  On the outside, it disappears against the sky, reflects and blends with the surroundings.  On the inside, natural daylight, views, openness, make the inhabitants feel connected to the outside, not confined in a box.

Ease of design and construction: Most, although not all, of heavily glazed façades are curtain walls.  The entire curtain-wall glazing system is engineered and manufactured offsite, essentially outsourcing the entire façade design to a curtain-wall manufacturer.  Even a traditional structural wall with inset windows requires less design effort, as glass itself becomes the main design element.

Glass as a green material?

Today, big windows are often presented as a part of a building’s sustainable design solution.  Glass is billed as a green feature.

Green design criteria emphasizes resource efficiency, well-being and safety of building occupants, and energy efficiency.

Does glass meet the green design criteria?

Resource-Efficiency:

• Glass is a resource efficient material which is made of abundant natural raw material such as sand and glass waste (cullets).
• Glass is 100% recyclable, it can be recycled in close loop over and over again.
• Glass recycling saves energy as cullets melt at a lower temperature than raw materials.
• Glass is very durable, short of breaking, it ages better in an urban environment than most building “skin” materials.

 Well-being and safety of building occupants:

• Glass brings in the natural daylight.  Daylight increases light levels and provides good color rendition.
• A study commissioned by the USGBC confirmed that daylighting improves office workers’ productivity, students’ performance, and brings increases in retail sales.
• Daylight has physiological and psychological benefits, and it positively impacts the immune system health.
• Well-designed glazing system combined with effective interior design can distribute daylight deeply into the building and minimize glare, thus maximizing the number of building occupants who benefit from daylighting.

 Energy Efficiency:

• Glass has high thermal conductivity, which means it has poor insulation qualities (for comparison, thermal conductivity of glass =1 W/(m.K), while insulating materials have <0.065 W/(m.K)).  This means that glass has high U-factor*.
• Glass, even the most technically advanced, has R-value** (insulation) below the cheapest legally allowed conventional wall assembly.  Most typical office buildings don’t even approach a third of that.
• Inefficient windows are responsible for up to 15% of a home’s heating and cooling losses according to the U.S. Department of Energy.
• Glazing needs to be no more than 25% (± 5%) of the total area of the building envelope in order to get the full benefit of natural daylight, according to data from the University of Oregon’s research on high performance envelopes (subscription only).  Beyond that percentage, glazing does not contribute more daylight, and starts to create a net energy loss.  ASHRAE 90.1-2007 energy code already specifies the amount of glazing that can be installed in commercial buildings.  Its prescriptive performance path sets a maximum glazing area at 40%.  To exceed that glazing percent, the building owner and the architect would have to show that a building will use less energy than it would with 40% glazed façade.

*U-factor – heat transfer coefficient that describes how well a building element conducts heat.  U-factor is generally only used to express the insulating value of windows (the smaller is the U-factor, the better are insulating properties)

**R-value = 1/U – measure of thermal resistance (insulation).  The higher is the R-value, the better is the insulating quality of an assembly.

Based on this assessment, it is not yet possible to apply a green material label to glass.  While it scores top marks on resource efficiency and occupants’ well-being, it does not score well on energy efficiency.

However, developments in glass technology combined with design solutions intended to maximize glass performance are working to mitigate this limitation.

Design solutions for maximizing glass performance

Sustainable building design seeks to gain the most solar heat possible in the winter, and minimize heat gains in the summer.  A successful design solution will take into account the climate, identify the most effective building footprint and orientation, and select the appropriate glass and framing options.

Climate: 

In cold climates, the most important energy consideration is heat loss, therefore the U-factor becomes the main concern.  Architects and builders should select glazing systems with low U-values and high R-values.  In warm and sunny climates, the most important energy consideration is solar heat gain, therefore a product with low SHGC (solar heat gain coefficient) that transmits less solar heat into the building is approprate.

Building footprint and orientation: 

Energy modeling exercise done by the engineering firm Arup for Environmental Business News (subscription only), showed that square building shape is the most economical.  On elongated buildings, which have larger façade area, the impact of increasing the percentage of glazing is greater.

With elongated building shape, building orientation plays a big role: when the longer façade faces east-west, the annual energy consumption can be up to 9.4% higher than when the longer façade faces north-south (depending on the type and percentage of glazing).

Glass Selection: 

To help architects and builders navigate product offerings, National Fenestration Rating Council offers, besides Energy Star, a comprehensive rating system with specifications in five categories:

1. U-factor – heat transfer coefficient
2. Solar heat gain coefficient (SHGC)
3. Visible light transmittance (VT)
4. Air leakage
5. Condensation resistance.

Glass selection becomes one of the most important decisions in creating a green glazing solution.  These are the most common types of glass products:

Insulated glazing (IG)

Most typical are double-pane windows.  Two window panes are separated by an airspace and sealed around the perimeter.  In the US, the airspace between the two glass panes is ¼” or ½” in most models.  Triple-pane windows are now becoming more common in the highest-performance buildings.  Triple glazing increases insulating properties of glass, but the extra glass panel correspondingly increases the risk of seal failure.  Also, due to weight considerations, glass and frame material choices are currently limited.  While triple-glazed windows offer superior insulation, they sacrifice passive heating opportunities in the winter.

For better efficiency, the airspace between glass panes can be gas-filled with argon or krypton.  An alternative is vacuum glazing, where panes are separated by a vacuum instead of inert gas.  Another energy efficient option is warm-edge glazing, where the spacer either incorporates a thermal break or is constructed from a low-conductivity material, as opposed to typical aluminum.

Low-E glazing

Low-E glass uses microscopically thin transparent coating of silver or tin oxide to allow short-wavelength sunlight to pass through, while blocking long-wavelength heat radiation, thus lowering the U-factor.  Low-E glass costs about 10% – 15% more, and can reduce heat flow by 30% – 50%.  The type and positioning of the Low-E coating affects the glazing performance and durability.  The problem with Low-E glass is that the sunlight it reflects contributes to the “heat island” effect outside of the building.

Spectrally selective glazing

One of the most common solutions to reducing the solar heat gain (lower the SHGC) is by using tinted glass.  The problem is that it blocks most of the visible light as well.  For this reason, spectrally selective clear glazing is more popular today, it selectively blocks out the solar spectrum outside of the visible band.

Dynamic glazing

Dynamic glass responds to changing light and heat conditions.  There are three types of dynamic glass:

Photochromic – when exposed to sunlight, photochromic glass darkens or becomes opaque, but it doesn’t control heat gain and may darken more in the winter when the sun’s rays are more direct.

Thermochromic – blocks out sunlight in response to rising heat, but the inability to control the glass’s response is a major disadvantage.

Electrochromic – is the most promising technology, in which the glazing is tinted on demand by supplying a low-voltage current.  These “smart” windows can be controlled by the homeowner or a building-management system.  In a clear state, electrochromic glass also blocks more UV light than typical Low-E glass.  When fully tinted, it blocks most wavelengths of visible light, protecting artwork and furnishings from fading in sunlight.  Electrochromic glass is expensive, but the costs have gone down significantly just in the last couple of years.

Frit on the glazing panels

Frit is a screen-printing pattern that serves to block heat gain while still allowing fairly good visibility through the glass.  There exist both translucent and opaque frits.  However, while frits are effective in reducing solar heat gain, they are not helpful with poor insulation qualities of the glass.  Therefore, they are best used in temperate climates.

Photovoltaic glass (PVG)

Solar-powered window is an insulated window with integrated photovoltaics.  A layer of transparent solid-state solar cells, at most three microns thick, is added to conventional glass.  It turns around 12% of the solar energy received into low-carbon electricity.  The current application of PV glass technology is mainly used power the building, and not yet even the whole building.  However, as technology develops, it has the potential to turn buildings into energy generators, not only supplying their own energy needs, but exporting the energy into the grid.  One of the manufacturers of this technology, estimates that it adds no more that 10% to the overall cost of the façade.

Framing: 

Energy-efficiency of glass cannot be discussed without discussing energy-efficiency of framing.  In fact, in today’s glass products the frame almost always perform worse than the glass.  Selecting the appropriate framing material will make a big difference in windows’ performance.

Aluminum is the most common frame material, but it is highly conductive, which causes high heat loss and cold interior temperatures in the edge-of-glass region during the winter. The result is a band of condensation or frost at the bottom of the glazing unit.

Wood frames are energy efficient, and can be obtained from a sustainable supplier.  However, they are expensive and need regular maintenance to avoid water or moisture damage.

Fibreglass frames are energy-efficient, low-maintenance and can be painted and repaired, but are expensive.

PVC frames, also known as uPVC, are made of vinyl and are not expensive.  They are energy efficient, low maintenance, and have very good moisture resistance, but once their original exterior finish fades or chips, they cannot be repainted or repaired.

Looking into the Future

Technological developments will continue to improve the energy-efficiency and performance of glass.  The development of new materials and new structural concepts will continue to perfect curtain-wall and window manufacturing techniques.  Developments in silicone chemistry will continue to enhance sealing and insulation materials.  With the maturing of PV technology, glazing will increasingly take on the energy supply role.

In short, the windows and the frames will become increasingly high-tech.

However, hopefully, the architects will also turn their attention to the simpler options: fine-tuning window placement to maximize passive solar design and maintain daylight; accounting for local climate and site conditions; finding the optimal glass to wall ratio for the specific needs of the project; seeking quality, rather than quantity of views.  These are basically free, if you take time to do them.

LEDs and CFLs are two of the most popular “green” light bulbs on the market today, but what is it that classifies them as “green”? Surely, efficiency isn’t only thing that makes truly environmentally-friendly light bulb. Does the light bulb contain harmful pollutants? Is the light’s efficiency or rated-life easily damaged by a rough environment? The light bulb’s packaging only reveals so much.

So, on that trip down the lighting aisle, which light bulb do you walk away with?

When you sit down and compare LEDs and CFLs, you’ll soon realize that one is decidedly greener. It’s not so hard to find out why; you just have to ask the right questions:

How Efficient Is Each Light Bulb?

Just like every other light source, the efficiency of the LED is measured in lumens per watt (lm/W), which is the amount of light produced by one unit of electrical power. Generally, a good LED lamp can generate twice as many lumens per watt as a CFL (60-100+ lm/W vs 30-50 lm/W). But that’s not the final score. LED technology is still improving. The U.S. Department of Energy believes that LEDs could easily attain an efficacy of 200 lm/W.

Less power used to make more light makes the LED the more sustainable choice.

How Does Each Rated-Life Compare?

In general, an LED will last around 10 times longer than a CFL. The rated life range of most LEDs can vary between 25,000 and 60,000 hours, while CFLs can last between 6,000 and 15,000 hours. Even after LEDs reach their estimated rated life, they continue to emit light but become progressively dimmer over time until they no longer emit enough light to be useful. On the other hand, CFLs do, in fact, completely burn out at some point in time.

So, LEDs last for a longer amount of time, and need to be replaced less often. That means less material waste in the long run, making LEDs the greener choice once again.

Does Either Light Bulb Contain Harmful Elements?

Mercury, a toxic substance that can attack the nervous system and brains of humans, is not found in any LEDs made by any manufacturer. But a CFL, like all fluorescent light bulbs, can’t work without very small amount of mercury placed within its glass envelope. The excited mercury is what allows the CFL to generate light in the first place.

Since LEDs contain no mercury, you don’t have to worry about releasing it into your home, or having it build up in waste facilities around the world.

How Durable Is Each Light Bulb?

External, environmental factors can easily degrade the rated-lives of CFLs. They’re extremely vulnerable to low temperatures, having a difficulties even turning on in temperatures lower than 32 degrees Fahrenheit. They also have sensitive electrodes that are easily disturbed by jarring vibrations or by turning on and off frequently. LEDs, however, are much more durable. The diodes they use to produce light thrive in the cold, and they don’t contain sensitive electrodes.

This means that well-made LEDs are much more likely to reach their rated-lives, meaning you’ll get more light out of each light bulb, and have to replace them less often.

Is Either Light Bulb Dimmable?

Due to the very nature of their technology, CFLs, like all fluorescent lamps, are difficult to dim.  They often need a special dimming ballast and a special dimmer control, and even then the CFLs seem to blink and then suddenly turn off near the lower end of the dimmer range. Every week more and more dimmable LED lights are introduced into the marketplace. A small number of LED lights are even beginning to mimic incandescent light bulbs while they’re dimmed; they appear to change their color temperature from white to a yellowish-white to an orangish-white to a reddish-white.

This feature offer more than an aesthetic benefit, it’s a sustainable one too. Dimming light bulbs is another way to save energy. A dimmed light bulb uses less electricity than one operating at full brightness.

What Does The Future Look Like For LEDs And CFLs?

CFLs are still a popular green lighting choice on the market today, but experts agree, they’re only a light source of the present. The development of the CFL has reached an endpoint, while the LED continues to improve. LEDs are truly the light source of the future. It’s a bright future, and a sustainable one too.

Conventional wisdom says that buildings are a sprawling, untamable black hole for energy. But a new analysis of federal data shows that the U.S. buildings sector has made enormous strides in efficiency over the last six years — potentially eliminating the need to build any new power plants to support growth in the sector through 2030.

When sustainable architecture guru Edward Mazria looked at the EIA’s latest Annual Energy Outlook, he noticed two surprising things: one, that 2030 projections for building energy consumption continue their steep decline; and two, that America plans to add over 60 billion square feet of new buildings by then. So even as a huge portfolio of new buildings is constructed in the next two decades, the energy needs in those buildings will be low enough to prevent the need for any new power plants to service them, concluded Mazria.

“There is no longer any need to build power plants to meet growth in the buildings sector,” said Mazria. “This is a monumental shift.”

Read More at Green Tech Media

With Carbon Dioxide Approaching a New High, Scientists Sound the Alarm

If uncertainty runs rampant in the global-warming debate, it is in part because scientific data is often too complex to be well understood by anyone but climate scientists.

This month, however, the world is likely to reach a scientific milestone that appears impressively scary even to those with only a cursory knowledge of climate science.

For the first time in human history, atmospheric carbon dioxide levels will surpass 400 parts per million, according Scripps Institution of Oceanography, which has been measuring carbon dioxide in the atmosphere at the Mauna Loa volcano in Hawaii since 1958.

“The 400-ppm threshold is a sobering milestone, and should serve as a wake-up call for all of us to support clean energy technology and reduce emissions of greenhouse gases, before it’s too late for our children and grandchildren.”

Read more at IHT Rendezvous NY Times Blog

LEED Passes First Green Light En Route To Federal Government-wide Use

“Those doing business with the federal government, civilian and military, should be cognizant that the GSA is on track to continue pursuing LEED certification.”

Last week, the Green Building Advisory Committee recommended to the U.S. General Services Administration that “GSA strongly encourage the use of the LEED standard across the government.”

This is huge, not only because the federal government operates a portfolio of almost one milli

on facilities (429,000 buildings and 482,000 other structures), making it the largest owner of improved property in North America, but it is also the owner of more LEED® certified buildings than anyone else. The federal government is also the largest tenant in LEED certified buildings on the planet.

Possibly most significant, the federal government has become an important agent of disruptive innovation improving the knowledge base on high performance buildings and leading the way in installation of cutting edge energy efficiency and sustainability technologies, that then find their way to the private sector.

Read more on GreenWizard

Overview and a bit of history

The very first house to achieve LEED for Homes Platinum Certification was a factory made modular home in Santa Monica, CA, in 2006.

Factory made modular houses, also referred to as prefabricated or prefab, are inherently more sustainable than their built on-site counterparts.  Factory process, by nature based on standardization, precision and efficiency, automatically minimizes raw materials and construction waste.  Another important advantage of prefab houses is the high quality of the exterior envelope, which is the most important precision assembly in a green building.  In a factory, a house is assembled from the inside out, with the drywall installed first and sheathing and siding last.  All the caulking and insulation work is done from the back of the drywall, behind any electrical or mechanical boxes, which creates an airtight seal.  Modules are often prefabricated with plumbing, electric and HVAC infrastructure.  Modular homes are built to a higher structural standard, because they have to be loaded on and off trucks and transported, possibly on un-paved roads.

Because of the process efficiency and economies of scale, modular homes cost 5 to 20% less than comparably sized built on-site homes.  Savings can be used towards offsetting the expense of energy-efficient and eco-friendly technologies, such as solar panels, geothermal heating, high performance windows, green non-toxic interior finishes, and high-efficiency appliances.

There are intangible benefits to consider as well, such as reduced construction time, lesser dependence on the weather and climate conditions, as well as minimal neighborhood disturbance and damage to the landscape.

The ideas of bringing prefab homes to the masses has been around since early 20^th century.  Sears Roebuck offered a house in a box in 1908.  Visionary architects from Frank Lloyd Wright to Le Corbusier, to Walter Gropius all designed prototypes for modular housing.  However, the ideas rarely went beyond the prototypes, derailed by high costs, lack of consumer demand, building regulations, and unanticipated maintenance issues.

Modular housing is much more widespread in Europe, where in some parts it makes up to 70% of all new construction.  In the US, according to the U.S. Census Bureau, modular construction accounted for about 5% to 9% of all new homes built in 2010. Nevertheless, technological advances, ever rising demand for energy efficiency and growing public preference for green design are making modular houses an increasingly attractive option for architects, developers and buyers.

LEED for Homes gives modular homes an initial certification advantage of 4 points (under MR 1.5 Off-site Fabrication), due to inherent manufacturing efficiencies, with added points for advanced framing and other elements easily incorporated into the factory building process, and points for recycling.  Under NGBS, 13 points are awarded under Section 601.5 (4) Modular Construction for the portion of the building prefabricated and located above grade.

It is important to understand the difference between the terms “manufactured” and “modular” houses, which are not synonymous and are often misapplied.

Manufactured homes (formerly known as mobile homes) is a term that refers to factory-built homes that meet the National Manufactured Housing Construction and Safety Standards, developed and enforced since 1974 by the U.S. Department of Housing and Urban Development (HUD).  This national standard is referred to as HUD-Code, and can be applied to houses in any jurisdiction without having to meet state and local codes.  Manufactured houses are typically single story, on a steel frame with wheels.

Modular homes, on the other hand, are built to state and local codes rather than a federal standard.  The modules are built in a factory and then transported to the site for final assembly on a permanent foundation.

Today, many architects use hybrid approach, mixing both built on site and prefabricated elements in a single project.  This allows to offer clients flexibility and highly customized details, while also taking advantage of the precision assembly and cost, materials and time savings of modular construction.

• Predictable outcome, both in terms of quality and aesthetic.
• Lower cost due to the process efficiency and economies of scale.
• Cost savings allow to offset the expense of energy-efficient solutions and green interior finishes and appliances.
• Efficient building envelope ensures high energy efficiency and good indoor air quality.
• Superior structural strength due to intrinsic requirement that the house be transported, sometimes on unpaved roads, and moved by a crane
• Factory-quality pre-installation of plumbing, electric and HVAC infrastructure reduces future maintenance issues.
• Architect-designed homes without having to hire an architect.
• Ability for clients to create customized layouts.
• Limited on-site construction.  Less dependence on weather and climate.
• Minimal neighborhood disturbance, and reduced construction-related noise, dust, erosion, and damage to existing site landscape
• 4 points in the LEED for Homes rating system ;  13 points under NGBS.

• Narrow floor plan and the boxy configuration works for functional areas such as bedrooms and bathrooms, but offers limited design options for grand living spaces that many affluent home buyers want.
• Lack of aesthetic appeal.  Until recently, the focus in prefab housing was more on efficiency and less on looks.
• Balance between cost and flexibility.  Prefab houses are most cost-effective when produced at a high volume, but most clients, especially on the higher end, require customization and flexibility.
• Cost of the house does not include site work and permits.
• Successful implementation, requires a contractor who is capable to correctly assemble the house on site according to specifications

In London, Murray Grove, a five story, 30-unit apartment building, completed in 2000 is a game-changing showcase project for what prefab construction can be.  The project was made out of factory-built modules in 27 weeks, with practically no construction waste.  Not only it is affordable and resource efficient, it is a bold piece of architecture.

In New York, a seven story mixed use building is being assembled from modular blocks in Inwood.  Start to finish, the project will take 9 months, as compared to 16-18 months of on-site construction.  Atlantic Yards, a planned 34-story affordable housing project in Brooklyn, N.Y, will use nearly 900 stacked modules and is also expected to cut costs and cycle time in half.

New computer modeling tools and rapid advances in material sciences and building technologies are changing both industry’s and buyers’ view of prefab housing.  Where a decade ago it was mostly associated with “cheap”, these days it is starting to become associated with “modern”.

The high cost of renewable energy is a common argument against building such power plants in developed countries, and this misconception also keeps many investors away. Yet, at the GEA conference it was shown that even lesser developed countries, such as Kenya (202 MW of installed geothermal) and El Salvador(204 MW), have already begun to install significant amounts of geothermal. Furthermore, if the levelized cost of a power plant is taken into account, including capital and operating costs, geothermal energy is the cheapest source apart from wind; the latter being an intermittent source. One must wonder why many more developed countries have not yet taken to this kind of energy?

Is it a Reliable Energy Source?

Geothermal energy is a renewable energy found abundantly around the globe. The technology takes advantage of the earth’s subterranean thermal energy. It has been used to produce heat for humans for thousands of years (think Roman bathhouses). Using geothermal energy for electricity began in Italy in 1904 in a plant in operation since then.

Today, twenty-four countries around the world employ geothermal energy to produce energy on a large scale. Total geothermal energy used worldwide is estimated to be 11,224 MW (GEA 2012). The top four countries utilizing geothermal are the U.S.(3,386 Megawatts), Philippines(1,904 MW), Indonesia(1,222 MW), Mexico(958), and Italy(883 MW). These numbers are not small considering it takes 1-2 Megawatts to power 1,000 homes. Yet, geothermal electrical energy in the U.S.only accounts for about 3% of all its renewable energy sources. However, an additional 5,150-5,523MW are under commission or “in the pipeline” (GEA estimate).

How does it work?

Geothermal energy is, by the nature of the technology, completely dependent on unmovable resources—the location of reservoirs beneath the earth’s crust. Wherever geothermal reservoirs happen to lie beneath the earth’s surface, there is potential to tap into its energy. However, new research has allowed developers to use geothermal energy in many more places in the world because it is now possible to tap into reservoirs with much lower temperatures and still produce electricity (by using what is called a binary plant).

Three types of electrical geothermal energy exist: flash, dry steam, and binary (as well as some hybrids). In a flash plant, water and steam are separated at the earth’s surface, with the steam used to power a turbine, which in turn creates electrical energy. In a dry steam plant, steam already exists and thus a separator is not required. Binary geothermal plants, employing new technology, require much lower temperatures (300 Fahrenheit as opposed to 500+ for the others). In this type of plant, the hot water is used to heat another “working fluid”, (such as pentafluoropropane), which can reach higher temperature more easily than water. The evaporating water (or steam) is mimicked by these working fluids to drive a turbine the same as a conventional geothermal plant.

Geothermal technologies tied to production of electrical energy are not feasible in many parts of the world which are far away from hot water reservoirs. However, the constant temperature of the earth’s core provides another ingenious way to heat and cool buildings (thermal energy), using the same concepts. Geothermal heat pumps (GHPs) pull heat down from a building during the summer; while in the winter, heat is driven up. This system can be used in virtually every corner of the globe to regulate building air temperatures and to produce hot water.

Bringing Light to Africa

If Kenya can develop geothermal energy on a grand scale, the technology is most likely proven and financeable. The Kenyan government has been largely responsible for the recent success of geothermal development projects. Through the Geothermal Development Company, (an autonomous state-owned company formed in 2009), the government mitigates the risk of geothermal plants; financial risks often impossible for the private sector to absorb.

This helps secure much needed foreign direct investment, without which would stymie exploration and procurement. Another clever policy tool employed by the Kenyan government was setting the import duty on renewable energy equipment and accessories to zero. This lessened the burden of importing expensive parts from around the world for renewable energy plants.

Geothermal energy in Kenya already accounts for nearly 16% of its total supply. Africa was once considered The Dark Continent, but may soon be lighting up with help from geothermal energy and other renewable energy sources. Indeed, Kenya is an integral part to Africa’s energy revolution.

Drill, baby, Drill!

What if developed countries began to seriously consider geothermal as a reliable, efficient, and sustainable energy source? Unlike other renewable energies, such as wind and solar, geothermal energy is not intermittent; meaning that a geothermal power plant can replace a coal or natural gas power plant quite easily.

New policy tools can help alleviate the burden of upfront exploration costs for geothermal energy, as the government of Kenya has done. And although the U.S. government and other governments of developed countries with geothermal energy promote, and in some cases subsidize geothermal energy, it is often confused with other renewable energy technologies. The confusion lies in the assumption that geothermal energy is like wind or solar energy, and is thus relatively new and unreliable.  Whereas the reality is geothermal needs policy that can attract new finance schemes, while also pushing further technological research (research which recently helped develop binary plants).