Green building design is focused on enhancing the positive aspects of a building site while minimizing the negative impacts that adding a building can have on that site and the surrounding area. There are a wide variety of green systems and building products that are being created to meet the growing trend of sustainable design. One of those product categories that has been instrumental in helping to achieve this goal is concrete masonry. Generally, there are four areas that concrete masonry has helped achieve this overall goal for sustainable sites:
1. Development Density
Providing denser buildings with smaller footprints has been demonstrated to be an important part of sustainable and walkable communities. The fire resistance capability of concrete masonry directly enables greater building density by meeting fire code requirements for separation of spaces. Further, the structural attributes of CMUs allow for vertical building design that can help minimize building footprints. In particular the modular aspect of concrete masonry lends itself to working well within small or irregular shaped building lots as easily as larger ones.
In terms of optimizing the most appropriate use of a site, it is worth noting that segmented retaining walls (SRW) made of concrete masonry has the potential to allow for the utilization of sites previously considered to be unsuitable due to slope or irregular terrain. In all, creating denser clusters of buildings can be coupled with a high ratio of open space that promotes biodiversity and effective environmental site design.
2. Community Connectivity
The modular nature of concrete masonry is actually quite optimal for dense sites that are short on space but high on pedestrian or vehicular traffic. The use of concrete masonry pavers of different types and styles introduces a design element that helps weave a particular building or series of buildings into the community fabric it is located within. This can be an attractive and effective way to create pedestrian access between the project site and neighborhood buildings and services.
3. Stormwater Management
In the interest of reducing disruption to natural hydrology patterns and minimizing the potential for pollution due to stormwater runoff, permeable paving has emerged as a very effective strategy. CMU pavers that are non-pervious and allow stormwater to permeate between them are not only effective in this regard, they provide an attractive aesthetic with a variety of colors and textures compared to monolithic paving choices such as asphalt or concrete. By properly specifying and designing with CMU site pavers, green building objectives can be met by reducing impervious ground covering thus increasing on-site infiltration and reducing stormwater runoff. From a general design standpoint, this approach can also increase the usable space on a site while requiring very little maintenance. Open grid paving systems are also recognized as reducing heat island effects and can thus provide this additional benefit as described further below.
4. Heat Island Reduction
Developed areas are known to have higher air temperatures than non-developed areas due in large part to the presence of dark- colored surfaces that produce heat when the sun shines on them. This phenomenon is referred to as a “heat island” and can notably affect the localized microclimate, producing an unwanted warming effect on people and buildings. As such, strategies to reduce this generated heat focus on either shading dark surfaces or providing hardscape surfaces that reflect rather than absorb sunlight to keep temperatures cooler. The unit of measurement for a material to be effective in reducing the heat island effect is the solar reflectance index (SRI). Based on a scale of 1 to 100 per standard ASTM procedures, a score of 0 would apply to a standard black surface (highly non-reflective) while a score of 100 would apply to a white surface (very reflective). The green building standard is to achieve a minimum SRI of 29 across hardscape materials. Happily, typical new gray CMU pavers have been tested at an SRI of 35 thus exceeding the minimum benchmark by over 20 percent.
By using a combination of these four CMU-based strategies in sustainable site design, designers can readily achieve a substantial number of points under the LEED rating system toward an overall green building certification level.
A special thanks to Echelon Masonry and Architectural Record for supplying us with this article.
Interested in sustainable design? Download our free guide on concrete masonry in green buildings.
