Archived decisions

COUNCIL MEETING, 27 NOVEMBER 2003

REPORT OF THE CABINET/LEADER

PART I

GREEN ROOF TECHNOLOGY

1 This item was the subject of a motion put forward by Councillor W.H. Wheeler at the July 2003 meeting of the County Council. It was as follows:

"This County Council being concerned with the future of both the urban and rural areas of Hampshire and the development issues of air and water quality and storm management asks:

That our architects look into Green Roof Technology to see if it would be suitable for:

(a) buildings that we are designing for public use;


(b) influencing other architects building within our county.


The benefits to the County would be:


(i) Increased area for insects and bird life to thrive;


(ii) To help control the water flow in the long term leading to fewer incidents of flooding."

2 Green roofs can be broadly categorised into two major types:-

(a) Intensive Roofs: The creation of more formal landscaped gardens including provision of small trees, shrubs and low planting, which are intended to be accessed by the building occupants for leisure purposes.


(b) Extensive Roofs: Primarily installed for aesthetic and environmental benefits, with access limited for the purposes of maintenance only.

3 The dense development of urban conurbations can give rise to barren deserts of concrete and tarmac, which prevent rainwater from naturally infiltrating the sub-soils. Green roof technology can help to address these problems by offering the perceived advantages of water management; energy efficiency; fabric protection and urban ecology including providing a better habitat for insect and bird life. However, set against these it is necessary to consider and review potential disadvantages, namely, imposed greater loads (requiring stronger and more costly support structures); roof leaks; maintenance difficulties; greater fire risk (green roof planting can die back during extreme drought presenting a potential fire risk and arson target); wildlife infestation (by enticing species which may be a nuisance); higher maintenance costs and adverse effects of the variable European climate (making sustainable planting regimes difficult).

4 So far in this country green roofs have been used relatively little. Notwithstanding this, the County Council's architects have, where appropriate, specified green roof technology on a limited number of its buildings over the last ten years or so. A good recent example of a suitable and relevant use was on Admiral Lord Nelson Secondary School, Portsmouth. This project employed green roof technology as an essential element of the design to obtain planning permission on this environmentally sensitive site. Other examples include the primary school at Stakes Hill Waterlooville and Minstead Study Centre in the New Forest where it is proposed to install a green roof over part of a new building. Subject to the approval of Government funding, it is intended that the Minstead project should be a further pilot for sustainability and "green" technologies.

5 The Buildings, Land and Contracts Panel has considered the notice of motion. Whilst accepting the undoubted advantages of green roof technology as referred to above, the Panel has noted that, in relation to the County Council's estate, the area of a building roof is usually a very small proportion of the site area and therefore the composite effect of green roof technology is very small. For example, the school estate has significantly more site than building area and improved drainage arrangements to playing fields and play courts would have a bigger impact on flood risk. The Panel has therefore taken the view that such projects ought to be considered but only where costs, site and design parameters are suitable.

6 The Leader has considered the matter at his decision day on 13 November 2003 and supports the conclusions of the Buildings, Land and Contracts Panel. Councillor W.H. Wheeler attended the Leader's decision day for the item.

RECOMMENDATION:

That green roof technology be considered for future County Council projects where costs, site and design parameters are appropriate.