Concrete Homes Newsletter
Concrete Home > Concrete Homes Newsletter > 2009 > November/December

November/December 2009

• Autumn Trails Paves with Concrete for Green Building Profits
• Wisconsin Builder Uses ICFs to build Affordable, Green Home
• Texas City Serves as Model for Energy Efficient Community
• Conservation Center Preaches what it Teaches
• Building Better with Concrete: Research Gets the Fast-Track at MIT
• Better Buildings in Less than Half an Hour
• Decorative Concrete Courses at World of Concrete
• Announcing  the 11th North American Masonry Conference
• Ask The Expert
• Upcoming Events
• Tools of Our Trade
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Autumn Trails Paves with Concrete for Green Building Profits

Authored by Barrett Davis of the Interlocking Concrete Pavement Institute

An independent living community in Moline, Illinois demonstrates the cost savings of permeable interlocking concrete pavement for developers.

Developer George Bialecki, Jr. finds that environmentally responsible design saves money and can lead to faster sales. At Autumn Trails, permeable interlocking concrete pavement saved thousands of dollars by eliminating conventional stormwater drainage, making PICP cost-competitive with conventional asphalt.

PICP Benefits

Mr. Bialecki selected PICP for many reasons. Beyond the cost savings, PICP was a great fit with his environmentally responsible approach to development.

• These include eliminating the burden on Moline’s aged storm sewer system and associated stormwater runoff fees.
• By eliminating a detention pond more land was available for income-generating housing units at Autumn Trails.
• PICP met the municipal requirements for pervious/impervious ratio cover.
• PICP eliminated storm sewer inlets and pipes because the site contained pervious soils. The 39,000 sf street portion of the Autumn Trails project demonstrated that these savings made very PICP cost-competitive with asphalt, $10.95/sf compared to $11.50/sf for asphalt.

All-Weather Construction

This pavement was built in winter. Since precast concrete units are manufactured in a factory they are unaffected by the outside temperature—even during construction. A source of unfrozen aggregate was available nearby and the open-graded pavement base layers and pavers were placed in the winter months. Mechanical installation equipment reduced paver installation time by 50% to 70% compared to manual installation. All together, this reduced the construction schedule by months, positively affecting financing costs and accelerating the opening date. This would not have been possible with conventional or pervious asphalt.

PICP has the structural capacity for low-volume streets and heavier loads under stabilized bases. PICP is part of a green building solution that works toward saving money for the developer and residents. To learn more about permeable pavement visit www.icpi.org.

Wisconsin Builder Uses ICFs to build Affordable, Green Home

“The Wellhouse” is an affordable, durable, sustainable concrete home in Waupaca, Wisconsin.  Designed by Ken Dahlin of AIA Genesis Architecture, LLC, and Built by John Durrant of Elm Valley Carpentry, this energy efficient home was built for roughly $100/sq. ft. and showcases new green building technologies. 

The owner, Jay Radtke, chose a concrete framing system for its thermal mass.  Along with the passive solar features, the thermal mass of concrete helps keep energy costs down.  Concrete, steel, and Novomesh were used to help protect the home and its inhabitants in the case of severe weather or crime. The home is also finished with Hardie Plank fiber cement siding, a more durable and energy-efficient alternative to vinyl or wood siding. 

State-of-the-art HVAC systems, combined with concrete flooring and radiant in-floor heating help reduce the amount of energy needed to sustain the indoor temperature. 

For more information on AIA Genesis Architecture, please click here. 

For more information on Elm Valley Carpentry, please call John Durrant at (715) 572-0922.

For more information on fiber cement siding, please click here. 

Texas City Serves as Model for Energy Efficient Community

Lubbock, Texas boasts the most successful ICF low-income home construction program in the U.S.  For more than a decade, the city has used Federal grant funds to build 120 ICF homes in Lubbock for low income families.  The new homes are quite energy efficient, with monthly heating bills of $70 to $80, rather than $400 per month for the substandard housing they replace. To highlight the program’s success, the National Community Development Association (NCDA) Southwest Region hosted it annual meeting in Lubbock, attracting 50 public officials from more than 30 Southwestern U.S. cities.

NCDA is an organization of local governments that administer federally-supported community, economic development, and housing programs across the country.   Attendees were particularly excited about the $2.7 billion in stimulus funds available from the Energy Efficiency and Conservation Block Grant Program to local governments for implementing projects that improve energy efficiency and reduce emissions.

PCA and the Cement Council of Texas (CCT) have actively supported Lubbock’s efforts through the years and were, respectively, platinum and silver sponsors of this event, which has already sparked interest from several attendees.
For more information, contact Sean VanDelist (svandelist@cementx.org). 

Conservation Center Preaches what it Teaches

The 2008 NCMA Design Awards recognized the Arnold and Mabel Beckman Center for Conservation Research with an award of excellence in sustainability. As a state-of-the-art facility at San Diego Zoo’s Wild Animal Park, the Beckman Center is a leader in research and wildlife conservation. Architects established goals for energy conservation, and selected concrete masonry units for the exterior (and some interior) walls. The building is registered with USGBC and owners are pursuing LEED Silver Certification for it.

The Right Look with a Sustainable Pedigree

By selecting various colors and textures of concrete masonry units, designers were able to create an aesthetic that works well in its setting, a nature preserve, and also harmonizes with the Center’s existing neighbors. The masonry materials have a high recycled content and are made locally, both of which contribute to them being sustainable. The architect also appreciated how the solid material performs. The high thermal mass of masonry provides a cooling effect in the Southern California desert-like climate. And because concrete materials are durable, they’ll not only create a long-lasting system, but they’ll also convey a feeling of permanence to visitors—which fits with the building’s educational focus.

Beyond the concrete masonry benefits just noted are other design considerations that make this building environmentally friendly. High ceilings and light shelves reduce the need for artificial light on the interior, saving energy to operate the building. A photovoltaic array located behind the building provides about 10% of its annual energy needs. High efficiency mechanicals and low flow water fixtures round out the green aspects. Inside and out, the Center focuses on using resources wisely to teach about conservation.

Jurors for the awards felt that this structure deserved to be recognized as an excellent example of sustainability. From structural walls to architectural appeal to efficient performance, concrete masonry is the key to this building. It contributed greatly toward achieving a sustainable structure, along with design approaches sensitive to the project goals.

For all the ways in which concrete masonry can contribute toward credits in the LEED rating system on any project, see the summary of categories in the table below.

Concrete Masonry and LEED® v3 Rating System

For more information on concrete masonry for low-rise construction, contact Jamie Farny or Donn Thompson.

For more 2008 NCMA Design Awards, please click here.

For information or to submit a project for the 2009 NCMA Design Awards, please click here.

Building Better with Concrete: Research Gets the Fast-Track at MIT

Concrete is the backbone of our housing, schools, hospitals and other built infrastructure, including highways, tunnels, airports and rail systems. To address sustainability and the environmental implications of using concrete, the Massachusetts Institute of Technology (MIT) has announced the creation of the Concrete Sustainability Hub, a new research center at MIT in collaboration with PCA and the Ready Mixed Concrete (RMC) Research & Education Foundation.

Although the construction industry is sometimes viewed as slow to embrace change, the Hub’s goal is to accelerate emerging breakthroughs in concrete science and engineering and transfer that science into practice. It has $10 million of sponsored research funding during the next five years to do this.

Better Buildings in Less than Half an Hour

Everybody’s busy, but wouldn’t you be willing to spend 25 minutes to find out how to build better buildings for future generations? Beyond good energy performance, sustainability is also about saving taxpayer dollars, improving safety and security, protecting property, upgrading aesthetics and addressing community issues. You can learn about PCA’s new High Performance Building Requirements and how PCA is working toward new standards in sustainable construction via a 25-minute recorded webcast, white paper, and adoption-ready amendments to the 2009 International Building Code.

Listen to the webcast
Download white paper
Download the High Performance Building Requirements for Sustainability, Version 1.5

Decorative Concrete Courses at World of Concrete

With a 5-day program, World of Concrete offers you a chance to educate yourself on many popular construction topics. Decorative concrete continues to be a favorite with attendees. Among the 10 seminars on decorative concrete are topics covering stamped, stained, overlays, polishing and sealing, and outdoor rooms. This is an opportunity to learn the latest techniques from experts in each field. And live demonstrations in the outdoor displays allow you to talk with installers, artists, and product representatives to learn as much as possible about the products and techniques that appeal to you.

Read about course descriptions and schedules here.

Announcing  the 11th North American Masonry Conference

The Masonry Society is now accepting abstracts for the 11th North American Masonry Conference (NAMC), which will be held June 5-8, 2011 in Minneapolis, MN. An abstract submittal form and other details about the conference are available at this link.

Ask The Expert

John Ries President Expanded Shale Clay and Slate Institute

Q: In what ways can lightweight concrete masonry be considered a sustainable building material?

A: Lightweight concrete masonry has several characteristics that make it sustainable. These include excellent energy performance, local manufacturing and availability, and decreased transportation and installation costs. Let’s focus on the energy performance as this is such an important area of green building that affects operating costs and occupant comfort for the life of a building.

Reinforced concrete masonry is a proven system for a wide range of applications in both commercial and residential construction. The U.S. specification for concrete masonry units (CMUs) is ASTM C90, Standard Specification for Loadbearing Concrete Masonry Units, which includes three density classifications for block: lightweight (≤105 lb per cu ft (pcf)) and normal weight (> 125 pcf) with medium weight in between. When appropriately designed, any density of masonry is suitable for any application.

Energy efficiency is a complex topic, and it’s important to look at all aspects that impact performance of a wall system.  For instance, R-values are a quick way to rate insulation, but there are other properties of concrete masonry that contribute to energy savings. ASHRAE 90.1, the Energy Standard for Buildings Except Low-Rise Residential Buildings (2007), is able to consider the factors affecting energy use, three main ones being:

• thermal mass
• thermal bridging
• insulation (thickness, rating, and location within the wall section)

Thermal Mass. Thermal mass can be described as the ability of a wall to store heat. One reason masonry (at any density) is effective with lower energy input is “thermal lag” which is sometimes referred to as the “flywheel effect.” [See figure] As outdoor temperatures fluctuate, masonry is slow to respond to changes. When air temperatures rise, masonry remains cooler. Alternately, with dropping temperatures, masonry doesn’t cool off quickly. This allows HVAC systems to be sized smaller yet still heat and cool effectively, providing comfortable interior temperatures while saving energy.

A concept related to thermal mass that’s a little less obvious is called thermal inertia. Thermal inertia is the combined effect of heat storage capacity within the wall and the thermal resistance to movement of heat through the wall. In concrete masonry, higher concrete densities increase thermal mass, but lower the wall’s thermal resistance. It is the combination of the two factors –thermal inertia– that determines how the wall contributes to building thermal performance in a dynamic environment. Even though lightweight masonry walls store less total heat, compared to normal weight masonry walls of the same thickness, they also release it more slowly which can improve overall building thermal performance.

Even lightweight CMU provide substantial thermal mass compared to truly “lightweight” wall systems such as wood frame or steel stud. IECC 2009 contains exceptions to its R-value requirements, allowing lower R-values for above-grade mass walls compared to frame walls in commercial buildings. (International Energy Conservation Code (IECC) 2009, International Code Council Inc., Country Club Hills, IL, 2009.  www.ICCsafe.org) IECC 2009 recognizes that lightweight CMU have adequate weight to provide the required thermal mass to qualify for the masonry mass wall exceptions. And of course they provide improved R-values compared to normal weight masonry.

Thermal Bridging. Bridging can be thought of as the “path of least resistance.” If a CMU contains insulation in its cores but the concrete is very dense, the webs of the block can still act as thermal bridges. The Expanded Shale Clay and Slate Institute has termed their lightweight block walls as SmartWall Systems® to indicate that this approach balances thermal mass with low thermal bridging, thereby maximizing effectiveness of the core insulation. This leads to optimum energy performance.

Using ASHRAE as the criteria, a simple example shows that a 12-in. SmartWall System® with perlite insulation in the cores outperforms a steel stud wall with R-19 batt insulation. And a single-wythe masonry wall is a simpler system to construct than a steel stud frame wall with batt insulation, veneer, and an interior finish.

Insulation. As energy considerations become more and more of a factor, all wall systems will be required to contain increased insulation. The strategy is certainly beneficial. But depending on when and how this is enacted, it’s already possible to build energy-efficient masonry construction with current products.

In Summary

Lightweight block satisfies mandatory criteria for building structural walls, such as strength to support live and dead loads, and provides inherent fire resistance. Yet the lightweight aggregate enhances energy performance of the system and reduces costs associated with transportation, handling, and labor—all of which can contribute to increased sustainability. The reduced weight of the block offers other advantages as well. It has great sound absorption characteristics, low shrinkage behavior (which may lead to fewer cracks in the wall), and a reduced seismic loading, which can be beneficial where earthquake forces are considered in design.

For more information on lightweight concrete masonry and SmartWall Systems®, please visit the Expanded Shale, Clay, and Slate Institute website at www.escsi.org or email jries@escsi.org.

 Share your own Concrete Homes technical questions by forwarding them in an email to: concretehomes@cement.org.  We will respond by email and may even publish your question in our next Concrete Homes Newsletter.

Upcoming Events

Tools of our Trade

Thermal Mass Comparison of Wall Systems

This 49-page report provides the thermal performance of 11 different structural wall systems: concrete masonry, insulated cast-in-place, insulated concrete forms (ICFs), and autoclaved aerated concrete (AAC) as well as wood and steel frame. The results illustrate the benefits of thermal mass, depending on climatic conditions for most of North America.

For more information, click here.

Standard Practice for Bracing Masonry Walls under Construction

This standard is intended to improve safety on the job site by providing design criteria for masonry and bracing systems used on free-standing masonry walls to resist specified wind loads during construction.

For more information, click here.

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