‘This is a wonderful book that should be on the desk of every architect and planner. It shows how

Could MFA really assist in finding opportunities to create positive impacts?
It offers at least one advantage. MFA can be more ‘place specific’. Tracing resource flows can help 

---

136
Positive Development
identify the distributional implications of existing development systems, so that design can work to 
reverse these problems. An MFA traces a substance or material throughout a system, production 
process or supply chain. This contrasts with methods such as life-cycle assessment (LCA), which, as 
we have seen, attempts to aggregate the inputs and outputs of all separate activities in the production, 
use and disposal of a product. The difference between LCA and MFA is largely one of focus: MFA 
follows particular substances (eg water, phosphorus, cellulose or cadmium) through human and/or 
natural systems. It shows changes that the substance undergoes from its origin in nature to its final 
disposal or reuse [Chapter 8]. But MFA could combine information about the transformation of 
materials (design) with input–output analyses (quantities). Although MFA has not yet really been 
used as a design aid, it has potential. To design a life form, after all, you would start with metabolism.
Similarly, to design a living building, you would start with securing sustainable sources of energy 
and food.
13
To design a living city, we have to create mutually beneficial relations with surrounding 
ecosystems. Fortresses do not work well in a siege.
How could mapping flows assist in improving whole systems?
Mapping an urban area in the wider systems context can identify waste in whole systems, not just 
component parts or stages of production. It can also identify financially profitable means of converting 
wastes to resources through cyclical processes. Some simple examples include:
•
Sewage
: Conventional sewage systems use electricity to pump wastewater and to oxidize the 
organic material. Then additional electricity and oxygen is used in aeration basins. The 
processes convert oxygen into millions of tons of CO
2
. Bricks can entombe solids from
industrial effluent waste and even sewage sludge, up to about 25 per cent of the fired bricks.
The process kills the microbes. But this is, of course, an ‘end-of-pipe’ industrial solution. It
is paradoxical that nutrients have become a source of pollution in our ‘modern’ form of
industrial development. Instead, we could adopt a more ‘rhizomatic’ approach. Organic
waste could be captured and used in gardens or agriculture, as in the city-to-soil project [Box
50]. Since the 1970s, in fact, some tree farms have been irrigated by nutrient-rich wastewater
from sewage plants to produce timber and sequester CO
2
.
• 
Cement
: Building products are a major source of embodied energy, groundwater pollution
and water consumption, from the production of components in factories through to
construction waste to landfill. Portland cement embodies water and accounts for about 90
per cent of CO
2
emissions from concrete. If magnesium carbonate is used instead, it would
soak up CO
2
, according to materials expert John Harrison.
14
Portland cement uses huge
amounts of energy to roast the calcium carbonate to make the ‘clinker’ that generates 7 per
cent of total global CO
2
emissions (a ton of cement = a ton of CO
2
). Likewise, titanium 
dioxide can be painted on existing urban surfaces to oxidize a range of air pollutants other
than CO
2 
(although it has negative impacts in production).