Housing

This page includes the following topic areas.
Density and human scale
Access to: Public transportation network, Recreation and Open Space, Employment, Cultural Amenities, Parking
Case Studies
Security, Aesthetics, Mixed use, Infrastructure
Housing Density

Introduction

Click thumbnails for a detailed view

Residential areas in urban environments must satisfy the basic human aspirations of attaining water, food, shelter, and security.

Security includes aspects of both safe neighborhoods and roads where families can spend time together outdoors and interact with neighbors. Security is also a component of the access to nearby employment. Crime should be rare and not physically threatening.

Mixed use development in urban areas can address access and safety issues by mixing residential units with retail shops, supermarkets, cultural amenities such as art, theatre, and dining; and to recreation and open space. When spaces are populated with users, crime rates drop.

You might think that communities could provide its citizens with each of the basic necessities but even in the US we know that a growing number of people live without decent shelter, have too little pure food to eat and are diminished by the fear of assault, burglary and rape.

There are secondary and tertiary human aspirations. Such as
Access to health care
Access to employment
Access to education, cultural amenities
Access to recreational opportunities
Access to transportation
Access to goods and services

Mixed use buildings adjacent to high quality open space

What four basic human aspirations must residential areas in urban environments satisfy?

Density and Human Scale

Density is generally expressed in Dwelling Units per Acre (DU). In small towns and typical subdivisions in America the densities range from 4 to 5 dwelling units per acre for detached single family housing.

Duplexes and cluster housing achieves 6 to 8 units per acre.

Two and threes story row or townhouses provide about 20 units per acre.

Three story apartment complexes achieve 25 units per acre.

Multiple story buildings can achieve densities from 50 to more than 100 units per acre. These high values are possible partly because underground parking becomes economically feasible in residential building 6 stories and taller. Surface parking requires more site area than the building if underground parking can not be provided. This results in dispersed buildings and lower residential densities.

The two images shown at bottom left are of a mixed use district in Turin, Italy. It is comprised of multi-family buildings ranging from 6 to 10 stories. Densities range from 50 to 125 units per acre.

Residential

In this aerial view of development in Florida, you can see almost exclusively single family housing that is replacing habitat.

View or a high density residential and commercial district. Density here is over 100 units per acre (Turin, Italy)

High quality multifamily housing with glass enclosed balconies

Density and Amenities

Higher densities often mean that developers provide high quality amenities for the residents.

In general, urban amenities increase with density. Name four such amenities that typically are attained at medium to high densities (of 50 to 100+ units/acre) that are not found at low densities < 50 units /acre.

Ten story residential tower

High density brings problems and opportunities. The table below suggests that urban amenities are more readily available as density increase.

*large retail—department stores, furniture stores, kitchen supply, hardware, appliance stores

Case Study One

As density increases, urban amenities increase in order to satisfy human aspirations. Higher density neighborhoods attract commercial amenities since the customer base is concentrated. Lower density neighborhoods don't merit these amenities from an economic return perspective. Some amenities are extremely expensive for the private or public sector to develop. These are often shared among adjacent neighborhoods.

The Millefonti District in Turin, Italy is one example that exhibits both extremes of the impacts of high density development. Comparing two contrasting neighborhoods identifies urban design strategies that are successful and ones that are not when density exceeds 50 units per acre.

This image shows a middle to upper middle class neighborhood as an example. The buildings are 8 stories and have penthouse units on top. The building are arranged around large landscape spaces. Density is about 50 units per acre. Notice that each unit has more than one balcony.

High Rise Condominiums

Describe the multi-family housing project in the Millefonti District, of Turin, Italy (case study one) in terms of density, private open space, semi public open space, parking, ground floor uses, security.

Name two problems encountered with the design and density of The Millefonti District in Turin, Italy.

Name two possible solutions.

Case Study One

Open First Floor

This complex is fenced and gated for security and privacy. Notice that the there are no units on the ground floor. Instead, building sits on one story columns that create a open landscape. There are views through the building from the street. This greatly increases the sense of space and openness of the urban landscape.

A negative aspect of this design technique is the fact that sound can travel through the open area under the buildings whereas in a ground floor buildings, it is blocked. This problem could be solved with the use of glass panels to preserve views but block noise. Privacy is also reduced but since the landscape is semi public and private balconies are provided this is not a great concern.

Case Study One - Project Design

The arrangement of the buildings established strong enclosure while framing views of other buildings in the complex to expand the sense of living within a landscape park. Since the open space is well enclosed and spatially organized, boundaries can better be identified and a sense of ownership can be obtained by the inhabitants. The distance between buildings is ample and the landscape is of high quality including semi private sitting areas, tennis courts and children's play areas.

Another benefit to this housing arrangement is that the neighborhood is not surrounded by major streets on all sides. In the plan view of a portion of the complex shows one access street that is used by only the tenants for access to underground parking. This is also the only above ground parking located within the building area. Not having a major road through this area reduces exhaust and noise pollution for the inhabitants.

Plan

Framed Views

Entrance to Underground Parking

Name three major benefits of the design used at The Millefonti District in Turin, Italy (case study one).

Case Study Two

Since the project was originally constructed as a low-income housing development, underground parking was not provided although the buildings are 8 t 10 stories. This omission is the source of most of the problems of project. About half of the space between buildings is parking but not clearly identified with particular buildings. Since the population of the project is high, it is difficult to determine whether people parking in the lots are residents of the project. This anonymity resulted in criminal activity and a reputation that discouraged prospective residents.

The parking lots are visually unappealing and compromise the usable green space. Planting are poorly placed and are dense enough to hide shrubs that unwanted people, making the building entries unsafe. The size and shape of the open space is awkward and prevents a sense of ownership for the inhabitants.

Unlike many other urban developments, there are no retail or food stores on the ground floor of the buildings. As a result, the inhabitants do not have immediate access to those amenities and since there is no commerce and no street life, no attention is paid to the neighborhood.

One pleasant aspect is the street trees which provide shade for the buildings, the walkway, and the parking along the street side. Another negative aspect, however, is that the buildings lack in decorative facades that play such a large role in assigning an identity to other projects. This is possibly the a reason for the high amount of graffiti on the building walls as compared to other nearby buildings. Other reasons for the graffiti can be attributed to its lack of significance in the surrounding community.

Plan

Parking

Dense Planting

Name five typical problems caused by poorly designed high density housing, (case study two).

Landscape and Density

One hundred to 120 feet between high rise residential buildings provides adequate privacy. This can be augmented by planting rapid growing trees that reach 80' or more. This vertical buffer is in proportion to the buildings but out of scale with the pedestrian. Therefore, under story planting of trees, shrubs and ground cover is necessary to form a comfortable space.

For a through investigation of residential densities in detached, duplex and multi-family buildings see the housing density section below.

Landscape between Buildings

Mixed Use

This image shows a mixed use building that includes retail shops, restaurants and entertainment places on the ground floor and residential housing above. Notice that the commercial walkway is covered and about 1 1/2 stories high. The residential units extend over the commercial walk to the curb edge. The residences each have balconies for some outdoor space and the balconies shade the windows of the units below.

Mixed use development at this density means that all of the daily shopping requirements of the residents are met within a block or two. Mixed use should include urban open space in immediate proximity to residential units. Access to these shopping and recreation opportunities is the compensation the urban dweller must have for the sacrifice of private open space.

Mixed Use

Urban Open Space

What are the characteristics of the mixed use development presented on the "housing" web page?

Access	Access to diverse activities and amenities such as public transportation, recreation and open space, employment, cultural amenities (theater, art, music) and parking is a benefit of living in high density situations. The availability of resources draws people to a city out of the desire for an exciting environment. Be certain the new designs contain access to the full spectrum of opportunities.

Security

Urban design can not solve the problem of crime in cities because the reasons for crime include poverty, despair, racial and religious prejudices and other maladies of modern life. But urban design can discourage crime through thoughtful design of public areas, residential districts and the provision of the elements of healthy neighborhoods. Create designs where safety is a priority by lighting and planting design that emphasizes visual access especially near building doorways and on routes between pedestrian destinations.

Gated Entry to Residential Housing

Name two aspects of safe neighborhoods.

Aesthetics

Regional architecture and landscape character are important to tie new development to local history and give inhabitants a sense of appreciation in their surroundings. As a result of mixed income housing, diversity in building size and style prevents monotony while also providing for increased parking opportunities. Rooftop gardens are a positive feature in the urban setting. Tall buildings can view roof top gardens on top of shorter buildings.

Landscaped environments can offer aesthetic quality while being low maintenance. Plantings provide unity from one block to the next. Street trees provide vertical and overhead planes as well as shade for pedestrian walkways, parking areas, and buildings—thus reducing energy costs from air conditioning. Shrubs along the perimeters of buildings increase aesthetics and aid in preventing vandalism.

Dense planting in an enclosed space between residential towers.

Roof Garden

Infrastructure	A benefit of urban development is that the availability of water, sewage, gas and data lines are more economical for the city and the developer to provide than in suburban areas areas.

Conclusion	The design of urban residential project requires more than attention to densities above 10 units per acre. It means the provision of recreation, great public landscapes and architectural character, art, shopping, transportation and employment is a compact district.
Sitting area in a residential area

Housing Density

Town Houses

This plan utilizes two story townhouses. The lot area is 535' by 270' (3.3 acres). There are 20 units per acre (66 total units) with above ground parking for 83 cars (1.25 per unit). The units are 700 square feet each. The yards are 600 square feet. 25% of the site is dedicated to circulation and open space.

Plan

What are the typical housing densities for single family (detached), three story apartments and 6 to 10 story condominiums (or apartments)?

Apartments	This plan features three story walk-up apartments. The lot area is 535' by 270' (3.3 acres). There are eight buildings of 12 units each for a total of 96. Each unit is 1600 square feet and the ground floor units have a small patio. The density is 30 units per acre. Circulation and open space amount to 25% of the site.
Plan

Six Story Building

This scheme includes six story apartment buildings with 40 units per building for a total of 240 units. This figure is reduce by two units per building to account for lobbies for an adjusted total of 232 units. The resulting density is 70 units per acre. The parking is on two levels accommodating 290 cars ( 1.25 per unit). The top of the garage structure serves as plaza or recreation space.

Plan

Ten Story Buildings

The site is 3.3 acres. One level of underground parking for 300 cars (1.25 cars per unit) is indicated by the shaded area. There are 120 units per building for a total of 240 units. The resulting density is 72 units per acre. Examples of this housing is shown at left. You can see that given ample space between buildings, views and access to high quality open space this pattern can result in a desirable permanent residence. When transportation and space between buildings is not adequately provided for then the quality of life for the residents is compromised. Therefore, comprehensive planning and urban planning controls are necessary to assure that the cumulative effect of many projects does not compromise the neighborhood.

Plan

Cul-de-sac Development	Theses plans are based on the need for a private yard in a suburban setting. The resulting densities are too low of effectively support mass transit (except) park and ride options.

Size/Density Comparison

The images at left show a variety of single family development patterns or attached housing with private yard. The table compares designs according to several measures. An estimate of seven to ten units per acre to support mass transit systems illustrate the marginal application of most of the designs to urban centers.

	Duplex	Duplex	Triplex	Quadplex
Square feet per unit	2440	2200	1800	900
Average lot size	7854	4888	6375	4628
Off-street parking	4	2+	2	2
Minor Street width	20	20	20	20
Minor street right-of-way	28	28	28	28
Street pavement per dwelling	761	615	715	535
Linear feet of street per dwelling	36	30	34	25
Curbs and gutters per dwelling	68	55	63	47
Density	4	7.25	6	8.25

Table

Duplexes

Maximum site utilization with semi-detached houses with no open space and straight street grid. The distance between pairs of units is 13'. The gross site area is 20 acres. There are 198 dwellings of 1,400 square feet each. The density is about 10 units per acre.

Plan

Mixed Density

This plan mixes single family housing, duplexes and row houses. Some public open space is provided for the row housing sections.

Plan

Townhouse Development

This plan features townhouses arranged in clusters. Small private outdoor spaces are provided. No public space is provided but social open space (intended for residents not strangers) is provided to each housing group with access through the private open space.

Plan

For this townhouse development what types of open spaces are provided?

What density would you anticipate?

Townhouse Development	This is another version of a townhouse development. It utilizes a typical city street grid making it a part of the fabric of the city. However, the grid is modified to eliminate through traffic routes that would encourage higher traffic volumes and speed.

Cluster Development	This plan groups pairs of duplexes into a cluster. Open space and exterior views. A series of these cluster developments could include interior parks. Access from two collector roads is a positive aspect of the plan. Private garages or carports are efficiently grouped near the collectors. The density is about 6 units per acres.
Plan

Three Units per Lot

This development provides for a compact development development pattern while providing semi-private outdoor space and garages. Enlarge the section first to discover how the dwelling s are distributed. The resulting density is 14 units per acre with shared social space and private balconies for private open space.

The last two images show how the clusters would be distributed in a large development. Images are from The New Urbanism by Peter Katz

Section

This section shows three units and represents a mix of housing types (single family ownership to rental apartment) on a single lot. What is the density of this type of development?

Guidelines

Development

Townhouse Group

This townhouse cluster groups units in a way that breaks the typical row house impact. Garages are included under two stories of living space. The units are tall and narrow. The density of this pattern is quite high if large private yard are not provided.

Elevation

Subdivision

This plan is of a single family residential subdivision. It is the model for much suburban development in the United States. The disadvantage of this model, and many of the examples above, is the single use. No commercial retail or office uses are included in the development. The combined impact of many of these subdivisions adjacent to each other is that residents are entirely dependent on the private auto to gain access to shopping and work. Mass transit can not serve subdivisions like this because the density is to low to justify the cost of the transit system.

Plan

This table of thumbnail images show additional images of the housing projects featured in the discussion or additional examples. All of the projects are in Turin Italy. All copyrights are reserved to Gary Austin. Do not reproduce without permission
			Suburban density

High density residential project	Pedestrian garage entrance	Vehicular garage entrance	Urban mixed use density