An idea for the Heart of Teignbridge

The government demands that the local plan provides sites for about 750 houses per year over the next 20 years in Teignbridge.

Where homes are built makes a difference to carbon emissions.

If you build small flats in town centres:

• There are fewer emissions from construction.
• There are fewer ongoing emissions.
• You don’t need a car, so there is a chance of no private transport emissions.

This post considers how far this could be achieved in the Heart of Teignbridge using the sites already identified in part 2 of the local plan. It is quite a long post which includes some feasibility calculations, which considers:

• Overall allocation of sites in the plan
• Allocation in the Heart of Teignbridge
• Housing need
• Housing density
• What does 70 dwellings per hectare look like
• What should the housing mix be
• What would the carbon emissions of this development be
• Comparison with development of more out of town sites

Overall allocation of sites in the plan

Part 2 of the local plan identifies more new sites than are needed to meet this when sites already allocated in the existing plan are taken into account.

The plan proposes that the allocations are split between the areas identified as follows:

• Heart of Teignbridge: 40% (c. 2,920 homes)
• Edge of Exeter: 24% (c. 1,800 homes)
• Dawlish: 14% (c. 1000 homes)
• Teignmouth: 1% (c. 100 homes)
• Bovey Tracey: 3.5% (c. 250 homes)
• Ashburton: 3.5% (c. 250 homes)
• Villages: 14% (c. 960 homes)

Each site has a suggested minimum and maximum number of homes, the following table is derived from these, and shows the level of choice in each area:

The columns in this table are sourced from the local plan documents as follows:

• Proposed distribution comes from ‘How much housing development is required’ in chapter 2.
• Min is the sum of the lower number of homes for each site in the area, taken from chapters 3 to 10.
• Max is the sum of the higher number of homes for each site in the area, taken from chapters 3 to 10
• Min <= 1ha is the sum of the lower number of homes for each site in the area, where the site is less than 1 hectare (and so suitable for a smaller developer).
• Max <= 1ha is the sum of the higher number of homes for each site in the area, where the site is less than 1 hectare (and so suitable for a smaller developer).
• %required min is the proportion of Min that would be required to satisfy the proposed distribution.
• %required max is the proportion of Max that would be required to satisfy the proposed distribution. This indicates the level of choice between sites given in the plan.
• Notes are any observations.

For the sake of argument let’s accept this distribution. It shows that there is a considerable amount of choice of sites in the Heart of Teignbridge, Dawlish, Bovey Tracey and the villages.

The rest of this post considers a possible allocation for the Heart of Teignbridge.

Allocation in the Heart of Teignbridge

Within the Heart of Teignbridge the sites are subdivided into Urban Renewal sites, which are on existing land that has already been developed for other purposes, and the rest of the Heart of Teignbridge.

Enough of the sites in the Heart of Teignbridge to meet the allocation of 2920 are shown in the following table:

Some of the sites towards the bottom of the table have been chosen to make up the numbers, but this allocation tries to avoid using green field sites that are away from current development.

This post considers putting the maximum possible amount of development into the Urban Renewal sites, this has a number of advantages:

• The homes delivered will all be within easy walking distance of:
  • Newton Abbot Station
  • Bus services
  • Newton Abbot town centre
  • The combined cycleway/footpath towards Bovey Tracey and Moretonhampstead to the north, and currently to the Passage House, soon to be extended to Teignmouth.
  • Hackney marshes
• The need for car ownership for day to day use would be minimised:
  • occasional car use could be provided by a car club.
  • Day to day car use would only be needed if work demanded it.
  • The need for further car parking would be minimised.
  • Car traffic growth would be minimised.
• These sites suit smaller dwellings and these is a proven demand for smaller dwellings.
• The combination of smaller dwellings and possibilities for active travel and use of public transport will give the smallest carbon footprint.
• Development of green field sites further out away from the centre is minimised.

We then consider other sites as near to the Town Centre as possible. The A382 development is already in progress, and there is relatively level access to the town centre along this corridor. This favours the Berry Knowles, Caravan Storage and Forches Cross sites. Unfortunately we still need to find 424 homes from the remaining sites.

Housing Need

The latest TDC housing policy document states that there is a waiting list of about 1000 applicants, and that 51% of these applicants are looking for a single bed property the proportion of property types required by applicants is shown in the following table:

Additionally 1 in 3 Teignbridge residents is over 65 years old, so probably doesn’t have children.

This says that there is a need to smaller properties, which could be flats.

There is clearly a need for social and affordable housing, as the waiting list recently has been about 1000 applicants, with about 350 applicants being housed each year. If the waiting list were to be substantially reduced over say 4 years to 100, then an additional 225 affordable homes per year would be required.

On average 137 new affordable homes are provided, other applicants are housed from existing stock. So the number of new affordable homes needs to increase to about 425. That would leave 325 open market homes from the obligatory 750 allocation.

Housing Density

Housing density is expressed in dwellings per hectare (dph), the area part of this measure includes estate roads, but excludes major thoroughfares.

The Teignbridge Urban design guide gives suggested densities for different situations:

From the developable area and maximum homes stated for Urban Renewal areas we can calculate the maximum dwellings per hectare:

Kingsteignton retail park site has a maximum density of 37.04, which is low for an urban area. This is a large site, so makes a big difference to the overall numbers, developing this at 50dph delivers an additional 175 homes.

If all the sites were developed at a density of 70 dph, then only 522 more homes would be required, so only the Berry Knowles and Forches Cross sites would be needed in addition to the Urban Renewal sites. Some sites are already allocated at more than 70 dph, so setting this as a minimum gives 2466 homes, so we are left with 454 to find.

If a minimum of 84.5 dph was set over this area, then 2932 homes would be delivered, which is enough to satisfy the Heart of Teignbridge allocation.

When I originally wrote this section I has misread the developable area of Brunel as 22 hectares, which makes the calculations better. If the developable are of Brunel or Kingsteignton retail park could be increased by 7ha between both sites, then the average density required overall could be reduced to 70dph.

What does 70 dwellings per hectare look like?

The following pictures are from the TDC Urban Design Guide:

So the Teignmouth block to the top left is at 70 dph. These examples are in the Teignbridge Vernacular. For a larger development such as Brunel, a complementary, but more modern style might be appropriate.

Consider the following example from the paper on housing density from Havant council:

I am sure that an imaginative architect could manage better!

So it looks like 70 dph is achievable if most dwellings are small and development is up to 3 storeys.

What should the housing mix be?

In order to substantially reduce the housing waiting list we need to deliver about 425 affordable homes per year. The mix for these should follow the mix of dwelling sizes required by applicants. If the urban renewal area were developed using this mix then the numbers would be as follows:

Here we have split 2 and 3 bed dwellings equally between flats and houses.

What would be the carbon footprint of this development be?

The carbon footprint that can be attributed to this development is made up from:

• Embedded emissions from construction of dwellings.
• Operational emissions from buildings in use.
• Transport emissions

For buildings emissions can be approximately calculated from floor area, we assume that development is to the minimum space standard introduced in 2015. This standard takes into account the number of occupants as well as the number of bedrooms, so a one bedroom flat may have one or two occupants. Apply the minimum floor areas in this standard to our required annual housing numbers:

Embedded emissions from construction depend on the construction type, the following values are assumed, and are applied to a floor area of 45969 m²:

CLT stands for cross laminated timber, which is a lightweight construction that can be used for up to 9 storeys. It lends itself to offsite pre-fabrication. CLT panels have good thermal properties.

The above embedded emissions do not take account of sequestration caused by the carbon sequestered whilst trees are growing being locked up in the structure of a dwelling. If this is taken into account it could be that CLT construction is carbon negative.

The operational emissions can be approximated from past energy performance certificates, combined with an aspiration that the new building regulations will reduce operational emissions to 25% of current building regulations. The average current CO₂ emissions from properties with an EPC rating C and above since 2015 is about 24kg CO₂e/m²/year. So we assume that these dwellings will be built to 6kg CO₂e/m²/year. This gives operational emissions of 276 tCO₂e per year.

As no car travel is necessary with these sites, there are no additional transport emissions.

If the urban renewal sites are built at 750 dwellings per year, it will take nearly 4 years to construct these dwellings. If we allocate embedded emissions to the year of construction, then the total emissions over the first few years would be:

Comparison with development of more out of town sites

Suppose that instead we built 750 brick built 3/4 bedroomed homes on sites 3 miles from the town centre.

Assume these have an average floor area of 100m², then the embedded emissions would be 73.1 tonnes per house, or 54,825 tonnes for 750 houses.

The operational emissions would be 450 tonnes per year.

We assume that a resident 3 miles from the town centre travels everywhere by car including travel to work, shopping and leisure. This might amount to 8,000 miles per year. Worse sites 3 miles from the town centre are generally at a higher altitude, so will require additional energy to go uphill that is not regained downhill. 8,000 miles in an average petrol or diesel car emits 2.5 tCO₂e/year, and a diesel 2.2 tCO₂e/year. Even an EV powered from grid electricity would emit 0.8tCO₂e/year. If we assume 20% EV, 40% diesel and 40% petrol, then the average car would emit about 2t CO₂e/year.

Even if we assume 1 car per house, then there are an additional 1500 tonnes from cars. It would be more realistic to assume 2 cars with one being used less, so effectively 1.5 cars.

Putting all this together for the first few years we get:

Once built this option has nearly 10 times the emissions than the alternative low carbon option.