Communities and Local Government

• Planning, building and the environment
• Planning
• Trees and High Hedges
• High hedges
• FAQs on high hedges
• Hedge height and light loss

Planning, building and the environment

Hedge height and light loss

How do you calculate light to conservatories?
Where a house has a conservatory, the opening between it and the house is taken as the window position for calculating the action hedge height - not the front or the side of the conservatory. This is because the glazing allows light in all round.

Are conservatories included as part of the house or garden for the purposes of the BRE light loss guidelines?
In terms of the calculations - in Hedge height and light loss - for the effect of the hedge on light to windows, conservatories are not taken into account. This is because they are a glazed unit (including the roof) and would be expected to get a reasonable amount of natural light from other directions that are unaffected by the hedge. In terms of the calculations for gardens, conservatories are considered part of the house and so should not be included in the garden area.

How do you calculate the area of oddly-shaped gardens?
One way of working out the area of gardens that are awkwardly shaped is to overlay a scaled plan with a grid - ie to divide it into smaller building blocks. This confines the complications to the margins and, even here, should give an indication of what proportion of the area covered by the grid falls within the garden.

The sole impact is to a bathroom window, which faces and is about 1 metre away from the hedge. As bathroom windows are excluded from the Hedge height and light loss calculations, does this mean that the complaint should automatically be rejected?
Hedge height and light loss (paragraph 5.1) states "Loss of light to toilets, bathrooms, store rooms and circulation areas (hall, stairs and landing) is deemed less important and such windows need not be analysed.". This is, however, only for the purpose of carrying out the BRE calculations. There is nothing in the legislation that says particular rooms are excluded from consideration. The fact that the affected rooms are bathrooms, does not necessarily mean therefore that the complaint is invalid but that little weight would be given to this particular ground of complaint. The reason for this is that loss of light to bathrooms is unlikely to have much impact on the complainant's general use and thus reasonable enjoyment of their property.

Where light to a window is affected by a hedge growing directly opposite, particularly where it is close, how long a section of the offending hedge is cut? Is it the section of hedge that is directly opposite the affected window or is there some kind of splayed system? For example -

Diffuse light can come from many directions, and the BRE guidelines have been developed assuming the whole length of the hedge is cut to the same height. In principle, you could leave intact the areas that were at an oblique angle to the window, but you would have to compensate for this by reducing the section to be cut to a lower height. You could use the vertical sky component technique in Site layout planning for daylight and sunlight: a guide to good practice to determine how much lower.

How do I calculate the action hedge height where the affected room has more than one window?
If the hedge is parallel to the wall in which the windows are situated then only one calculation needs to be carried out, as the action hedge height will be the same for all windows.

If the windows are on separate elevations (eg one facing the hedge and the other at 90^o to the hedge) but are both affected by the hedge then the action hedge height is calculated separately for each window wall, and the lowest value taken (see paragraph 5.5 of Hedge height and light loss).

In some cases there may be other windows in the room that are not affected by the hedge. The process here would be to calculate the action hedge height for the affected window and vary this height to take into account the impact of lighting provided through other apertures (eg windows or skylights not affected by the hedge). There are no formulae/calculations to assist in assessing by how much the action hedge height should be varied. It is a question of judgement (eg based on the size of the windows and the amount of light coming through them) whether a higher action hedge height might be justified and what would be appropriate.

The hedge grows at an angle to the window. It is not opposite, at right angles or 45^o. How do I calculate the action hedge height?
Use the most appropriate formula in Hedge height and light loss ie the formula for the angle closest to that of the hedge.

How is the action hedge height calculated when the hedge is not actually on, or parallel with, the complainant's boundary, as in the example below?

The Hedge height and light loss calculations do not apply in these cases because hedges in such places are unlikely to have a significant effect on light loss. In such cases, factors or problems associated with the hedge other than light loss are likely to be given more weight in the decision making process.

How do I calculate the action hedge height for a garden where the hedge only covers part of the boundary?
Changes made to paragraph 4.2 of Hedge height and light loss in October 2005 explain that you should carry out the full calculation - garden area divided by effective hedge length - to produce the correct effective garden depth. This should then be multiplied by the relative orientation factor.

I have a hedge which bends and faces different compass points, eg South East and East. How do I calculate the action hedge height?
In this case you would need to calculate a new orientation factor (see Table 1 of Hedge height and light loss) to apply to the whole length of hedge. First, multiply the length of each section that faces a different direction by the factor for its orientation. Then add together the results for each section of hedge and divide this total by the total length of the hedge. This will provide a new orientation factor. Because the garden in such an example will not be rectangular you would then use the full calculation in paragraph 4.2 of Hedge height and light loss to obtain the 'Effective depth' of the garden. This should be multiplied by the new orientation factor to produce the action hedge height which would apply to the total length of the hedge.

Example

	Length of section of hedge (m)	Orientation	Factor from Table 1	Length x factor
	8	South East	0.3	2.4
	14	East	0.4	5.6
Totals	22			8

New factor = Total of length x factor (8)/ Total length (22) = 0.36

Action hedge height = Effective depth of garden x New factor

Only a small portion of a hedge borders the complainant's property (see the example below). What does the Council consider - just that portion or the whole hedge?

 

Under the Anti-social Behaviour Act 2003, an offending hedge need not be located on the boundary between the complainant's property and that of the hedge owner. The whole hedge, therefore, can be considered, provided that it satisfies the legal tests. However, when assessing the impact on light to the complainant's property, using the Hedge height and light loss calculations, only the portion of hedge on the complainant's boundary is taken into account. Work could, nevertheless, be justified to the portion of the hedge not situated on the boundary, depending on other grounds of complaint. If the Council are likely to require work to the whole length of the hedge, it may be appropriate to consult other neighbours who could be affected.