For years, apartments have been designed without regard to building efficiency. Commercial projects have always considered the net-to-gross ratio (the ratio of net rentable space versus total gross building space) and are usually 82 percent to 85 percent efficient, while apartments have been far less efficient, with an average ratio of 70 percent to 75 percent.
In both small and large apartment complexes, the loss of rentable square footage due to excessive wasted space, poor product, and inexperienced designers can have a sizeable effect on the overall cost of construction and the financial return on the owner's investment. Developers are anxiously seeking ways to maximize usable space on sites that would not typically be economically viable, while at the same time reduce construction costs.
However, they also must find ways to edge out the growing competition in this market. In order to compete, communities must maintain design appeal and quality construction. By addressing and prioritizing new design concepts and key construction line items, developers can build communities that maintain a competitive edge by offering architecturally exciting exteriors, attractive and efficient floor plans, and technically sophisticated amenities.
Cost-Saving Techniques In an effort to drive down costs, some developers will use modular products or eliminate critical design components. In many cases, the benefits are strictly short-term – communities tend to be poorly designed and constructed. Exteriors are ordinary, materials don't last, and units are small and inefficient. Ultimately, these projects can't compete in class A markets and instead must compete in secondary and tertiary markets with limited rents.
Today, we are seeing numerous opportunities to affordably build rental multifamily housing that achieves a density of 28 to 30 dwellings units per acre (dua) using new building technology that can cut construction costs by 10 percent to 15 percent. The savings are achieved through design by addressing efficiency and creating a much higher net-to-gross ratio, rather than removing components that sacrifice the overall design of the development.
Structural elements, such as the foundation, exterior walls, roofing, framing lumber, and drywall, are the heart of the budget. These aren't public elements. Residents cannot see them, and they don't enhance the community. But by giving considerable design attention to line items such as trusses, doors, windows, or cabinets during the predevelopment stage, we attack inefficiency without sacrificing design. When these items are standardized and used repeatedly throughout the project, a significant savings in construction costs will be achieved.
Alternative Concepts Conventional multifamily buildings have often been designed and constructed with breezeways or corridors that extend from one side of the building to the other. Individual units open out to the breezeways, and residents may exit the building using stairways on either side of the building. However, these breezeways are inefficient. They reduce the usable space available within the total area of the building footprint, and they increase the overall size of the building.
Because breezeways, balconies, and stairways account for a large percentage of wasted space, an alternative is to minimize them. One idea is to remove them, allowing the developer to reduce the gross square footage without altering the net square footage. The building maintains the same net rentable space as conventional garden apartments, but the efficiency ratio has increased to 82 percent or higher.
Minimizing the excess circulation space leads to smaller, more efficient buildings that not only allow densities to be higher, but also require less exterior wall construction, slab, and roofing materials. This will reduce hard construction costs – savings of 10 percent to 15 percent per square foot.