The Wide View On Shade

The season has arrived when Valley dwellers look for parking spaces under trees rather than the closest parking spaces to their ultimate destinations. This is the time we mimic the habits of native creatures: seek shade, stay inside, search for water and moisture and venture out in the early mornings while it is still bearable. This primal strategy becomes a way of life for Phoenicians five months out of the year. What many of us don’t know is that we can expand upon such shade techniques by incorporating them into our homes, thereby staying cooler and keeping energy bills down.

Shade is usually associated with blocked or filtered light, but it isn’t the visible light with which we are concerned; it is the accompanying radiant heat. If we expand our definition of shade to the idea of eliminating or deflecting radiant heat, we broaden our strategies for living within the desert climate while holding onto visible, nourishing daylight. These strategies include: orientation, vertical shading, horizontal or canopy shading, high-performance glazing, reflective roofing, hardscape minimization and microclimates.

Orientation is the most elemental and most undervalued form of shade maximization. Structures should be built with the lengths facing north and south. Garages or least-occupied spaces should be situated on the west end of the structures to shade the conditioned, habited area from late afternoon heat. Homes should also be designed with the main entries, as well as major windows, facing north. Developers and builders often ignore these design basics because of the inconvenience they place on maximizing the number of lots in a given development, much to the detriment of the homeowners’ comfort and future residential resale value.

Vertical shading is important for east- and west-facing windows and walls. Shading can take the form of trees, high shrubs, trellised walls, perforated metal screens, shade screens, landscape walls, mounded earth, exterior window security blinds, ceramic radiant barrier paint and anything else creative architects and homeowners can design. While interior blinds provide some relief, they suffer a losing battle since heat has already entered the home.

Horizontal or canopy shading is universally beneficial. Residents can experiment by employing overhangs to keep heat off of the walls and windows; however, on the south side of structures, overhangs should be designed to shade sun in the summer, but allow the sun to generate heat in the winter. High or clerestory windows underneath overhangs are a great way to let in daylight with reduced direct radiant heat. Shading roofs provides the same thermal benefit as parking under a tree in commercial parking lots.

Continuing technological improvements in energy efficiency give us greater design freedom like the availability of high-performance glazing. Windows are the weakest link in the building thermal envelope, but are getting better. Until recently, Low-e2 was the performance benchmark for windows. The new SunCoatMax coating by Milgard reduces solar heat gain by an additional 34% while only cutting visible light by an additional 7%. At 65% visible light transmittance, your eyes have an easier time adjusting between outdoor and indoor views. Other manufacturers have come out with similar technologies, too. SageGlass products allow homeowners to control the amount of light peering through their windows. They can dramatically reduce solar heat gain in their darkened state. Other options allow daylight without views, such as tubular skylights and Kalwall daylighting panels.

Reflective roofing also serves as a strong strategic ally in the effort to block radiant heat, as roofs receive the brunt of the annual summer assault. Energy Star-certified roofing products or high-scoring Cool Roof Rating Council products reflect radiant heat off buildings, dramatically reducing the workload of attic insulation and effectively “shading” the home. Spectrally-selective cool, metal roofing comes in a variety of colors and a “green” or vegetative roof will also block heat from getting through the roof.

Hardscape minimization reduces the heat island effect, as well. Hardscape both reflects heat onto the house and stores heat. Even with overhangs, a concrete slab on the south side of a building will bounce heat toward windows and walls creating an oven effect. Improvements include plants, ground cover, decomposed granite, mulched landscaping, permeable concrete (vs. solid slab), planters buffering the hardscape from the home, canopy-shaded hardscape and thermally-broken hardscape (such as pavers with soil joints between them).

Microclimates, such as entryways, create many benefits in shading against summer heat. Entryways should be protected with shade, but they can also be framed with vegetation, with the greener vegetation located closely to the entrance. The combination of shade and plant evaporative cooling creates a thermal decompression zone. This results in less energy loss when doors are opened and also allows the human body to adjust more smoothly to the harsh outdoor climate or the conditioned indoor climate. A similar concept applies to the entire landscaping scheme. Xeriscape zones should be located further from the building, while grass and water features (used sparingly) should be located next to the home, cooling the building.

So as the season turns from hot to hotter, keeping shade strategies in mind will help get Valley residents through the harsh summer. Applying such strategies on a larger scale will also help the Valley combat the urban heat island effect and provide some relief for us all.