Shadow Assessment
Using ArborShadow R4
Once your tree survey schedule is in place and the site plan loaded the usual requirement is to determine the level of shadow interference into a garden area of a proposed dwelling. On very large sites where a hundred or more such gardens exist it is a good idea to eliminate some from analysis to save time.
To do this, first carry out a general visual assessment of a proposed site layout against the existing trees. A number of potential conflicts can be ignored. For example, trees located on the northern boundary of a site will only produce shadows south of their position during the summer months and then only at the very beginning of the day (approximately 5-7am) and towards the end of the day (6pm +). So a short note in a report can discount all trees on a northern boundary. Of course this only works for northern latitudes (UK, USA, etc.); if you live in Australia then you would discount all trees located on a southern site boundary!
This can also be applied within a site itself, if an area north of a tree is open space or perhaps a road junction then a conflict is unlikely. The highest potential for conflicts is where trees are located south of gardens. A typical green field development will be enclosed with hedgerow and trees. Back gardens are then typically arranged so they back onto the hedgerows causing no end of potential conflicts.
Another general point is when trees are located on a western site boundary they will generally only cause shading to the site in the afternoon, once the sun has moved past solar noon the tree shadows move eastwards. Likewise trees on an eastern site boundary will only cause shadowing into a site during the morning. Its up to you to decide the relevance of this.
As an example, if an assessment shows that a particular tree will shade an adjacent garden for most of a morning at all times of a year but it can be demonstrated that for every afternoon of a year the garden will be completely shade free and enjoy uninterrupted potential sunlight, then that may be considered to be an acceptable level of sunlight. And may be defensible if an owner decided to appeal against refusal for pruning or removal to abate the morning nuisance.
Arboricultural Consultant
The relevance of tree shadows in relation to new development is important to ensure that proposed recreational areas such as gardens and windows (on building elevations) will not be excessively shaded by adjacent trees. If these areas do become excessively shaded, the tree may become a target for pruning or even removal. By understanding the position and motion of tree shadows at an early stage in the planning process, such problems can be avoided (by, for example, adjusting the proposed site layout).
It is the job of the contracting arboriculturist to keep his/her client informed of these issues and to supply them with data from which they can modify their plans. The assessment of a trees shading capability should be included within an Arboricultural Implication Study (AIS) which considers the relationship between existing trees and a proposed development.
Tree Officer
Tree officers working for Local Authorities are obliged to ensure that important trees are retained where possible in relation to new development. They must consider a number of factors, including the issue of sunlight. Councils receive a large number of requests to prune or remove protected trees due to sunlight interference. They can of course refuse the requests, but this may be overturned on appeal to the Secretary of State, who may, for example, judge that the light loss is unreasonable and the tree should be removed.
To avoid such a set of circumstances arising, local authorities must ensure at an early planning stage that the issue of light interruption, both in the present and in the future has been considered. They should demand information from the developers demonstrating that a reasonable level of sunlight will be available to gardens, recreational areas, windows etc
Once your tree survey schedule is in place and the site plan loaded the usual requirement is to determine the level of shadow interference into a garden area of a proposed dwelling. On very large sites where a hundred or more such gardens exist it is a good idea to eliminate some from analysis to save time.
To do this, first carry out a general visual assessment of a proposed site layout against the existing trees. A number of potential conflicts can be ignored. For example, trees located on the northern boundary of a site will only produce shadows south of their position during the summer months and then only at the very beginning of the day (approximately 5-7am) and towards the end of the day (6pm +). So a short note in a report can discount all trees on a northern boundary. Of course this only works for northern latitudes (UK, USA, etc.); if you live in Australia then you would discount all trees located on a southern site boundary!
This can also be applied within a site itself, if an area north of a tree is open space or perhaps a road junction then a conflict is unlikely. The highest potential for conflicts is where trees are located south of gardens. A typical green field development will be enclosed with hedgerow and trees. Back gardens are then typically arranged so they back onto the hedgerows causing no end of potential conflicts.
Another general point is when trees are located on a western site boundary they will generally only cause shading to the site in the afternoon, once the sun has moved past solar noon the tree shadows move eastwards. Likewise trees on an eastern site boundary will only cause shadowing into a site during the morning. Its up to you to decide the relevance of this.
As an example, if an assessment shows that a particular tree will shade an adjacent garden for most of a morning at all times of a year but it can be demonstrated that for every afternoon of a year the garden will be completely shade free and enjoy uninterrupted potential sunlight, then that may be considered to be an acceptable level of sunlight. And may be defensible if an owner decided to appeal against refusal for pruning or removal to abate the morning nuisance.
Arboricultural Consultant
The relevance of tree shadows in relation to new development is important to ensure that proposed recreational areas such as gardens and windows (on building elevations) will not be excessively shaded by adjacent trees. If these areas do become excessively shaded, the tree may become a target for pruning or even removal. By understanding the position and motion of tree shadows at an early stage in the planning process, such problems can be avoided (by, for example, adjusting the proposed site layout).
It is the job of the contracting arboriculturist to keep his/her client informed of these issues and to supply them with data from which they can modify their plans. The assessment of a trees shading capability should be included within an Arboricultural Implication Study (AIS) which considers the relationship between existing trees and a proposed development.
Tree Officer
Tree officers working for Local Authorities are obliged to ensure that important trees are retained where possible in relation to new development. They must consider a number of factors, including the issue of sunlight. Councils receive a large number of requests to prune or remove protected trees due to sunlight interference. They can of course refuse the requests, but this may be overturned on appeal to the Secretary of State, who may, for example, judge that the light loss is unreasonable and the tree should be removed.
To avoid such a set of circumstances arising, local authorities must ensure at an early planning stage that the issue of light interruption, both in the present and in the future has been considered. They should demand information from the developers demonstrating that a reasonable level of sunlight will be available to gardens, recreational areas, windows etc
