4. Assessing and comparing alternatives

Alternatives can come in two broad types of sets.  The role of SEA assessment will depend on the set in question.

Some alternatives will be mutually exclusive: decision-makers will choose one alternative from a limited set. An example is whether or not a city centre should be pedestrianised (it can only be one or the other, or  maybe partial pedestrianisation, but not both pedestrianisation and not pedestrianisation); or whether or not an energy policy should promote nuclear power. The role of SEA will be to compare the options in terms of their environmental/sustainability impacts, and help choose the best option.

Other alternatives will be mix-and-match combinations of individual "building blocks" of plan components. For instance, a transport plan could include various combinations of Park and Ride sites, bus lanes, congestion charging etc.; a water policy could include various combinations of pricing mechanisms, leakage reduction, provision of new reservoirs etc.  The role of SEA will be to identify the environmental/sustainability impacts of the various components, and help to 'screen in' those components that should clearly be in the strategic action, and 'screen out' those that should clearly be rejected.

Some alternatives will be a combination of both of these types. The SEA will need to distinguish those components that are mutually exclusive and compare them; and those that are mix-and-match and screen them.

Revisiting some of the alternative sets/packages from the last unit, try to figure out whether each is mutually exclusive, mix-and-match or a combination:

Set 1: For licensing of an offshore area for oil and gas exploration and production:

  • To license the whole area
  • Not to license any of the area
  • To license those parts of the area that are not environmentally sensitive.

Set 2: For a national strategy on forestry:

  • preparation of sites using: machines, prescribed burns, chemicals
  • afforestation through: sowing tree seeds, planting tree seedlings at all sites, natural regeneration at all sites, site by site decision of whether to plant trees or allow site to regenerate naturally
  • sowing tree seeds using: aerial application, hand seeding, seeding in conjunction with scarification
  • provision of tree seedlings as: bareroot, container grown
  • growth of tree seedlings by: private sector, government workers

The table below shows what an assessment of alternatives could look like (just how this is done will be discussed later). A few things about the table are worth noting and can be seen by clicking on the link below the table.

Documenting alternatives 1: Levels of development in a local authority
Key components of option Option 1 - Continuation of Trend
Option 2 - Trend +
Option 3 - Trend ++
Most Positive Outcome Most Negative Outcome

Option 2 is the most sustainable, and is the authority's preferred option. Option 1 is unlikely to trigger the level of activity necessary to regenerate the authority: it would risk a continued slow decline in service provision and employment levels and an increasingly aged population (with consequent implications for the economy and healthcare). Option 3 is a high-risk option. The high population growth could trigger a renaissance in the authority: new households could prompt and support a sea change in terms of inward investment, business start-ups etc. These changes could, in turn, encourage further inward migration and regeneration. On the other hand, there is a risk that so much new housing might not be accompanied by the necessary level of jobs and services. This could result in the authority essentially becoming a suburb for more thriving areas outside the authority. Option 3 would also require the development of greenfield land with consequent risks to landscape character. Option 2 represents a compromise between the certainty that current trends -- i.e. Option 1 - are not sustainable in the sense that something has to change within the authority if investment and regeneration is to take place on a significant scale and the uncertainty surrounding large-scale growth -- i.e. Option 3 -- and the risks that this entails. However Option 2 would still involve a doubling of the pace of development across the whole plan period. To ensure that land is used effectively, it will be essential to ensure that new development is carefully managed to ensure that its contribution to the economy and sustainability is maximised. This will entail ensuring, for example, that new housing is designed to contribute to wider regeneration objectives and that policies are put in place to encourage sustainable design and construction.
change in population - 0.5% + 8% + 16%
new housing 6,000 10,000 14,000
new employment land - - several large sites
SEA objectives (NB colour denotes severity of existing problem, based on environmental problems identified in the context-setting stage: darker = more problematic) Assessment of options against sustainability appraisal objectives
1. To conserve and enhance biodiversity + ++ ++ ++
2. To protect, enhance and make accessible for enjoyment, the countryside and the historic environment ? -? 0 -?
3. To reduce the need to travel and encourage alternatives to the car 0 + + 0
4. To create a high quality built environment 0 + ++ -
5. To promote sustainable forms of development and use of natural resources - 0 ++ --
... ... ... ... ...
Cumulative impacts 0 + ++ -

Below is another example of how the comparison of alternatives can be documented. The example relates to alternative approaches to mitigating climate change in a UK regional spatial strategy. Note the clear statement of what the preferred option is and why.

Documenting alternatives 2: How strenuously to mitigate climate change in a regional spatial strategy
Possible approach* Advantages Disadvantages

* 1, 2 and 3 are broadly mutually exclusive approaches; 4 and/or 5 can go with any of 1, 2 or 3.

Decision taken and reason why: Combination of approaches 1 and 5:

"All plans, strategies, investment decisions and programmes in the region will aim to help to meet the region's target to reduce greenhouse gas emissions by at least 20% below 1990 levels by and 25% below 1990 levels by 2015 by:

  • increasing urban density and energy efficiency
  • promoting walking, cycling and the use of public transport
  • minimising resource demands from development
  • encouraging redevelopment of previously developed land..."

It is not realistic or reasonable to include a requirement to exceed national building standards due to legal problems (i.e. the regional planning body and local planning authorities could be held to be ultra vires in setting requirements that are addressed through other legislation other than Planning Act powers), economic problems (i.e. developers would find it less profitable to build in the region, thereby reducing the number of homes built in the region) and social problems (i.e. a lower number of house completions could result in fewer affordable homes being built, the delivery of which is dependent on the volume of housing development prescribed in the regional spatial strategy.

1. Don't go beyond national standards * No need to make special case to government, and no legal problems for the Regional Planning Body or Local Planning Authorities in being held to be ultra vires
* No additional short-term economic costs associated with e.g. renewable energy, improved design etc.
* No need to revise/re-examine housing figures, the development of which will facilitate needed levels of affordable housing
* 2010 climate change targets unlikely to be met; cost implications in terms of flooding, extreme weather events etc. is likely to be very significant -- but this is not directly linked to RSS actions
2. Require mitigation (or adaptation) beyond national standards * Most likely to lead to reduced energy use, improved energy efficiency, renewable energy generated
* Responsible approach to a pressing global problem
* Energy White Paper suggests that regions should develop strategic approaches to energy, which should "include regional targets (such as for renewables and energy efficiency) negotiated between the region and central government" and "act as a contribution by the region to the development of national policy." This suggests that regions can exceed national targets
* Building Regulations have already been reviewed to provide for a 40% increase in energy efficiency over and above standards in 2003; they are often reviewed, so even if the RSS set standards beyond Building Regulations, they could soon be out of date
* Building Regulations are statutory and should only be exceeded in exceptional, justifiable circumstances
* The planning system should not be used to duplicate other controls.
* Higher building standards could increase development costs and impact adversely on affordable housing.
* A small increase beyond Building Regulation standards would have a minimal impact on total regional greenhouse gas emissions, but could deter investment and put the region at a comparative disadvantage to others.
* Any more stringent standards could be perceived as being arbitrary
3. Encourage mitigation (or adaptation) beyond national standards * No need to make special case to government * May well have little/no effect in practice beyond A.
4. Different approaches for different sub-areas, e.g. less stringent requirements for parts of the region in need of regeneration * Responsive to local/regional circumstances, with more equitable approach to costs * May be difficult to justify different approaches for different sub-areas
5. Promote complementary policies, e.g. local supply networks, making urban areas more attractive places to live and work * Could be responsive to regional circumstances, e.g. Y+H's higher than average representation of the power generation industry
* Benefits beyond climate change, e.g. social benefits of local supply networks
* Costs associated with some complementary measures, e.g. short term costs of major improvements in public transport


September 1, 2006 Uncategorized — riki @ 12:40 am

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