Measuring Urban Density
Quantitative and Qualitative analysis
Authors Note: As an architect, I often get frustrated when peers talk and showcase designs without any proof or data to back them up. It's not their fault as this is just not given importance while studying in universities. Having said this I understand how difficult it is to measure the intangible at times, hence a system or standards need to be devised. This is an attempt at precisely that.
From the previous article Art, Architecture and Archeology, we learnt architecture has the ability to be mechanical and at the same time show empathetic concern which can be associated with the intangible — Art!
With densifying urban landscapes, efficient and humanised landscapes become essential. Measuring— predicting — executing become the workflow for any future design. In this article, we delve deeper into the first two parts about how and why we measure and predict.
Why do we measure density?
Measuring density aids design, future-proof cities, provide essential housing, improve livelihood, reduce environmental impact and reduce the strain on our infrastructure.
The data-backed design ensures the functionality of the design. Although a lot of factors play a role in affecting the path to design hence we have summed up a few essential metrics to be followed.
What kind of data needs to be measured?
Data can broadly be divided into measurements of the tangible and intangible. In other words, the quantitative and qualitative. One is not better than the other but a successful combination of both can get us the desired results.
Measurement Through Quantitative
Quantitative simply means data that is universal and can be calculated using mathematics.
Who needs this kind of data and why?
Within the current scenario urban planners are most concerned with FAR measurement, realtors with dwelling units to maximise profitability, the government agencies care more about population numbers, which are tied to city services and infrastructure needs and the residents with network density which deals with the porosity and livelihood of the fabric.
What are these metrics?
- Floor Space Indes/ Floor area Ratio: Size of buildings(Built-up) on a given size [Floor Area/ Site area]
- Dwelling Unit Density: The number of homes in an area [Dwelling Units/Area]
- Population Density: People Living in an area [People/Area]
- Network Density: Infrastructure for passage of a certain width [Total length of street/ Total land area m/ha]
How to analyse the data?
Spacemate (Typomorphology): Berghauser Pont and Haupt developed “Spacemate”, a tool to represent the built environment. Showing FSI and GSI simultaneously within the graph, spacemate showcases morphological typologies and built form in detail allowing comparisons to be made with spaces with similar densities but having very different built forms.
The graph is formed by FSI and GSI on the y- and x-axis respectively and network density on the z-axis. The combination of FSI(intensity), GSI(compactness), L(height) and OSR(pressure on non-built space) on a 2-dimensional graph can help differentiate urban forms and network density in 3dimentions showcasing the porosity of a fabric.
Agreements made on the basis of spacemate have an objective nature assisting in supporting the design. Spacemate also increases control opportunity at a high level of scale and design freedom at a low level.
At an early stage of design, it can aid by setting upper or lower limits, and zones in the diagram can be delineated.
How to calculate?
Floor Space Index (FSI): FSI is the total floor area of the building divided by its site area; for an urban area, this is the total floor area of all buildings divided by the land area. FSI can be any positive value. It is also called ‘built potential’, ‘plot ratio’ or ‘floor area ratio (FAR)’.
Dwelling Unit Density: Dwelling units is the number of dwelling units within an area
Formula
Population Density: Population density is defined as the number of people within a plot of land. However, high population density doesn’t lead to a better livelihood. It is also often co-related to dwelling unit density as the higher the number of units, the higher the population but this does not stand true for all cases.
Use
By increasing population density, it boosts the productivity and affordability of a city
Formula
Network density: A network is defined as an infrastructure with a certain robustness and of a certain width. The length of the network is used to define network density.
Use
The average distance from street to street (Fabric width/ grain size) -The porosity of the fabric ( Width of open space) -The street profile
Formula
Ground Space Index (GSI): For an individual building, GSI is the ground floor area of the building divided by its site; for an urban area, this is the total ground floor area of all buildings divided by the land area. GSI can be any positive value up to 1, where 1 would represent a building entirely covering its site. GSI is sometimes referred to as ‘site coverage ratio’.
Formula
Pressure on non-built space(OSR): As the name suggests it refers to the unbuilt green spaces
Formula
Height(L): The number of floors of the structure
Formula
TareSpace: Surplus land which may be public or private
Formula
Grain of the Network and Street Profile width (w and b): Network density can be used to calculate a vindictive grain size (w), or distance from street to street in a square grid of the urban fabric using the formula:
Formula
Measurement Through Qualitative
Measurement of FAR and other such formulae are not necessarily useful indicators of success as they only measure size or quantity. Qualitative criteria are needed. The success needs to be measured in terms of how the built forms support everyday life. They can be measured in terms of higher quality of life and resilience and adaptability to social ecological and environmental change.
What are the qualitative ways to measure densification?
Diversity Of Built Form
Dwelling, working, learning and recreating in close proximity allows us to live more locally and this diversity is more sustainable.
Dwellings of different sizes would be close to each other for example a large apartment could host multiple smaller apartments another smaller building may house only a few large apartments. The urban form should comfortably accommodate social housing alongside private housing, public institutions alongside commercial ventures and corporations alongside cooperatives.
Urban form to be useful in everyday life is dependant on the proximity of different activities, hence it would be required to host buildings of varied volumes and shapes.
What to look for?
- Different kinds of buildings
- Different dimension
- Different typologies
- Smaller plots
- Smaller subdivisions
- More diverse ownership
- Balance of Building components: ground floor, middle and top
- Visual Variation
Diversity Of Outdoor Spaces
Exposure to fresh air, physical activity, and interactions with others help boost physical and mental health. Along with this hybrid spaces allow for more activities to take place while creating multiple degrees of privacy.
Spaces for mobility do not need to be constant and can change along with their needs adhering to their surroundings. Spaces such as terraces could also be negotiated and opened for public use.
Certain spaces can be permanently shaded increasing the intractability to the outdoors while having some kind of protection from the weather.
What to look for?
- Different kinds of private, shared and public outdoor spaces
- Hybrid spaces that connect inside and out
- Streets as public spaces and public spaces as places for mobility
- Various volumes for semi-open outdoor spaces
Flexibility
Life is a constant change and the village or the neighbourhood is never finished. If an urban space is truly resilient it must be responsive and capable to change. It must adapt to changing economic cycles, densification, changing needs and functions.
The urban morphology must be responsive in the short, medium and long term.
The short-term changes may be temporary markets, extensions, potted plants etc. Ground floors are the most likely to change as they have direct access to the public realm. They do not disturb existing users and subdividing it allows for greater diversity and flexibility.
In terms of the extension to an office, expanding family, or need for renovation, enclosed spaces like courtyards could serve well for this function because they are hidden and acoustically muffled they don’t disturb their surroundings.
Ancillary buildings and spaces are particularly useful in accommodating change including densification, as there are no objections regarding new volumes. Outbuildings also have the advantage of having direct ground-floor accessibility. Spaces like basements and attics are useful for accommodating densification from the inside.
What to look for?
- A greater proportion of built volume is ground floor
- Ancillary spaces such as outbuildings, basements and attics
- Room on the edge of buildings for temporary overflow
- Independent Fractals
- Backs with room for growth
Human Scale
Humanising is crucial as we want people to experience comfort, protection and connection to the biodiversity. We can make neighbourhoods that people will want to go to and spend time in.
Lowering building heights and expressing the most at eye level can be beneficial and economical. The eye-catching ability of a built form is at 3 scales, the building level, the ground floor and the openenings.
What to look for?
- Ideally four or five stories
- Particular care for the eye experience
- Designed through the lens of 3 stages of eye-catching
Walkability
Walkability refers to the smallest but the most crucial movement in our lives. It boots efficiency as having multiple functions within short spans could be easily accessed. In otherwise extremely dense settings it can work as an alternative to courtyards, plazas and other congregational spaces.
What to look for?
- Walk in-through-up buildings
- Visual connection and physical access between inside and outside
- Narrower streets or front gardens
A Sense Of Control And Identity
The built-up should be made up of identifiable, distinct and physically defined spaces which can vary in size from common backyards to crossroads. Having a sense of belonging creates a feeling of ownership and community. It can greatly help in futureproofing as the residents themselves become the owners, the caretakers and the residents of their society.
What to look for?
- Enclosure and spatial Clarity
- Significant corners
- Hierarchy of identifiable territories
Greater Biodiversity
What to look for?
- Protected spaces and edges
- Small-scale water management systems with slower water filtration
- Green walls and roof
- Pleasant micro climate with natural and self-shading
Smaller Carbon Footprint
What to look for?
- Fewer exploded facades ( thanks to joined buildings)
- Simpler construction and foundation systems
- Emphasis on self-built architecture and materials
Sources
[1] Understanding Density, measuring density (Stuti Vij) — Broad understanding of quantitative means of density measurement
[2] Density and morphology: from the building scale to the city scale(Daniel Godoy-Shimizu, Philip Steadman &Stephen Evans)
[3] The Spacemate: Density and the typomorphology of the urban fabric(Meta Berghauser Pont Per Haupt)
[4] Spacematrix- Space,Density and Urban Form(Meta Berghauser Pont Per Haupt) — Formulae
[5] Soft City- Building Density for Everyday Life (David Sim) — Qualitative data
