Light-reflective floors- including several concrete surface treatment methods- can improve illumination inside buildings by reflecting light from both the sun and ambient lights, according to the Portland Cement Association.

Instead of adding more costly lighting units or increasing the intensity of artificial lighting, the project team can create a polished floor using white cement, or by using shake-on bright colors before a slab treatment. Either method can increase light-reflectance. Polished concrete can require high levels of expertise to achieve proper surface quality, so mock-ups are often suggested.

The specifier has several options for the slab-full depth, two-course toppings, and shake-ons-to create a permanent reflective surface that will not wear off as paints and coatings can over time. In some cases, slag cements can be used to save on the cost or scarcity of white sand or brightly colored crushed rocks; slag and portland cement can significantly brighten concrete though other pozzolans may darken concrete.

Fine white sands or crushed white stone aggregate within the mix can achieve uniform concrete color if white concrete is not cost-prohibitive. Before polishing a 28-day cure slab, shake-on pigments can be applied to achieve the same reflectance as white concrete. Such a floor surface is a passive means for improving illumination and can add to the potential for nearzero-energy construction.

For more information about zero-energy construction, see the October edition of The Construction Specifier, at http:// www.kenilworth.com/publications

Sources: Greg Schwietz, CSI, CDT, and Paul Nutcher, CSI CDT, "Zero-Energy Buildings;" The Construction Specifier, October, 2010, p. 52.

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