The design intent for the 27 residences at Atwater Crossing in Los Angeles was to create homes with open floor plans that were filled with natural daylight and that would also meet the highest level of environmental standards. That goal was the starting point for a number of unique decisions that would ultimately result in LEED Platinum certification for these homes.
Atwater Crossing Residences are CMU, Not Wood
A combination of materials was selected to express the design, including concrete masonry, not a typical material solution for low-rise, townhouse or single-family home construction in Los Angeles. But, according to architect Charles Kluger, AIA, of Kluger Architects, Signal Hill, CA, along with using recycled building materials whenever possible, the design team included many features that make the project friendly to the environment. One surprising decision was to avoid the use of wood.
Wood accounts for less than 1 percent of building materials in the homes at Atwater Crossing. Using concrete masonry units readily contributed more material points for Platinum LEED certification because it was a long-lasting sustainable material, according to the designers. The exposed concrete masonry materials contributed about two LEED points to the project. To earn a Platinum LEED designation, the building construction is expected to surpass California Title 24 Energy Code Standards by 15 percent or more. The energy-conserving envelopes of the homes were reported to be more than 30 percent better than Title 24 requirements, with the concrete masonry shouldering the additional energy loads imposed by the front and back glass walls.
Instead of wood, the homes are constructed of materials the designers deemed “recyclable, renewable, and abundant.” The homes are constructed primarily of steel and concrete masonry, along with aluminum and glass. The hybrid structure combines CMU shear walls on the sides of the homes and a steel moment frame, according to Kluger, to account for potential seismic loads. The intent was to highlight, not hide, construction materials, so very minimal wall finishes were employed. The minimal finishes used were selected to harmonize with the simple nature of the design. Even the garage doors almost seamlessly integrate into the glass curtain walls. The designers chose the rusticated look of split-face block for exterior walls, and inside the smoother side of the block is left exposed for half of the wall surfaces.
The first floor includes a two-car garage with a dumbwaiter to the kitchen above and also to a usable roof deck. There is a flexible space intended as an office or extra bedroom, and a fully retractable glass wall at ground level. The second floor contains open plan public spaces, and the living room space has more retractable glass walls. Elevated ceilings in the private living spaces on the third floor contribute to the strategy of featuring the masonry materials as a design focal point, again with judicious use of other finishes. A walkable roof comprises the fourth floor, with its concrete masonry walls, outdoor kitchen, private bath, garden and lounging area.
Concrete block, steel beams, and even mechanical systems were left exposed by design. The full-height masonry walls offer many aesthetic and maintenance advantages in the individual units, and serve to visually anchor the front and back curtain wall ends of the homes at the street. The homes have been virtually maintenance free.
The materials selected for the residences at Atwater Crossing provided the design solution of vertically integrated open volumes with cantilevered floors. The open plan means that daylight can reach into all spaces.
“The idea of natural light filling every space was significant,” according to Kluger. The glass curtain wall systems open front and back walls of the envelope to natural light. The architects specified glass doors for interior rooms, so spaces that are typically illuminated by artificial light in most housing developments are instead filled with natural light at Atwater Crossing.
Kluger points out that all the materials used, but in particular concrete masonry,“are very low maintenance and highly durable, which means that future resources will not be required for upkeep and repairs. The block is natural and enduring, reinforcing the idea that these are timeless buildings.”