Mixed-use development refers to the practice of containing more than one type of use in a building or set of buildings. In zoning terms, this can mean some combination of residential, commercial, industrial, office, institutional, or other uses.
History
Throughout most of human history, the majority of human settlements developed as mixed-use environments. Walking was the primary way that people and goods were moved about, sometimes assisted by animals such as horses or cattle. Most people dwelt in buildings that were places of work as well as domestic life, and made things or sold things from their own homes. Most buildings were not divided into discrete functions on a room by room basis, and most neighbourhoods contained a diversity of uses, even if some districts developed a predominance of certain uses, such as metalworkers, or textiles or footwear due to the socio-economic benefits of propinquity. People lived at very high densities because the amount of space required for daily living and movement between different activities was determined by walkability and the scale of the human body. This was particularly true in cities, and the ground floor of buildings was often devoted to some sort of commercial or productive use, with living space upstairs.
This historical mixed-used pattern of development declined during the Industrial Age in favor of large-scale early capitalist-style manufacturing in single-function buildings. This period saw massive migrations of people from rural areas to cities drawn by work in factories and businesses that grew up around them. These influxes of new residents needed to be accommodated and many residential districts arose at this time with domestic housing being their primary function. Thus began a separating out of landuses which had previously occurred in the same spaces. Furthermore, many factories produced substantial pollution of various kinds. Distance was required to minimise adverse impacts such as noise, dirt, noxious fumes and dangerous substances. Even so, at this time, most industrialised cities were of a size that allowed people to walk between the different areas of the city.
These factors were important in the push for Euclidian zoning premised on the compartmentalisation of land uses into like functions and their spatial separation. In Europe, advocates of the Garden City movement were attempting to think through these issues and propose improved ways to plan cities based on zoning areas of land so that conflicts between landuses would be minimised. Modernist architects such as Le Corbusier advocated radical rethinking of the way cities were designed based on similar ideas, proposing plans for Paris such as the Plan Voisin and Radiant Citythat involved demolishing the entire centre of the city and replacing it with towers in a park-like setting, with industry carefully sited away from other uses.
In the United States, another impetus for Euclidian zoning was the birth of the skyscraper. Fear of buildings blocking out the sun led many to call for zoning regulations, particularly in New York City. Zoning regulations, first put into place in 1916, not only called for limits on building heights, but eventually called for separations of uses. This was largely meant to keep people from living next to polluted industrial areas. This separation however, was extended to commercial uses as well, setting the stage for the suburban style of life that is common in America today. This type of zoning was widely adopted by municipal zoning codes.
With the advent of mass transit systems, but especially the private automobile and cheap oil, the ability to create dispersed, low-density cities where people could live very long distances from their workplaces, shopping centres and entertainment districts began in earnest. However, it has been the post-second World War dominance of the automobile and the decline in all other modes of urban transportation that has seen the extremes of these trends come to pass.
Benefits
Throughout the late 20th century, it began to become apparent to many urban planners and other professionals that mixed-use development had many benefits and should be promoted again. As American cities deindustrialized, the need to separate residences from dangerous factories became less important. Completely separate zoning created isolated "islands" of each type of development. In many cases, the automobile became a requirement for transportation between vast fields of residentially zoned housing and the separate commercial and office strips. Jane Jacobs' influential The Death and Life of Great American Cities argues that a mixture of uses is vital and necessary for a healthy urban area.
Zoning laws attempt to address these problems by using mixed-use zoning. A mixed use district will most commonly be the "downtown" of the community. The mixed use guidelines often result in residential buildings with streetfront commercial space. Retailers have the assurance that they will always have customers living right above and around them, while residents have the benefit of being able to walk a mere number of yards to get groceries and household items, or see a movie.
Drawbacks
Mixed use development is seen as too risky by many developers and lending institutions because economic success requires that the many different uses all remain in business. Most development throughout the mid to late 20th century was single-use, so many development and finance professionals see this as the safer and more acceptable means to provide construction and earn a profit. Christopher B. Leinberger notes that there are 19 standard real estate product types that can obtain easy financing through real estate investment trusts. Each type, such as the office park and the strip mall, is designed for low density, single use construction. Another issue is that short term discounted cash flow has become the standard way to measure the success of income-producing development, resulting in "disposable" suburban designs that make money in the short run but are not as successful in the mid to long term as walkable, mixed use projects.
Mixed use commercial space is often seen as being best suited for retail and small office uses. This precludes its widespread adoption as the trend to ever-larger corporate and government employment accelerates.
Mixed use residential space is best suited to those who prefer public amenities to private, regulated personal space. The lack of private outdoor space for kids and pets is anathema to some, particularly in some North American cultures.
Construction costs for mixed-use development currently exceed those for similar sized, single-use buildings[citation needed]. Challenges include fire separations, sound attentuation, ventilation, and egress. Leinberger explains,
Good urban architecture costs upward of 50 percent more than typical suburban buildings. In urban areas, residents and businesses demand a higher quality of building, since you are walking past them, not driving by at 45 miles an hour with the buildings set back 150 feet.
Additional costs arise from meeting the design needs: In some designs, the large, high-ceilinged, columnless lower floor for commercial uses may not be entirely compatible with the smaller scale of walled residential space above. Often the parking space requirements for businesses exceed those of residential development. Thus, mixed use projects often require a large number of parking spaces that may be difficult to finance. It should be noted however that in mixed-use developments in some denser areas, owning an automobile might be considered a luxury rather than a necessity.
Others maintain that modern consumers prefer big box retailers, as evidenced by the fact that most grocery shoppers today would prefer the convenience of weekly shopping, as opposed to picking up each day's food items from many small shops.