In June 2006, the then Department of Environment, Heritage and Local Government Published Wind Energy Development Guidelines for Planning Authorities (the Guidelines) under Section 28 of the Planning and Development Act, 2000. The aim of these guidelines was to provide advice and information to planning authorities, prospective developers and local communities with regard to wind energy.
The Department of Environment, Community and Local Government is currently conducting a targeted review of the Guidelines soley in relation to three potential impacts: noise, setback distances and shadow flicker. It is a targeted review focusing on these specific issues. All other sections of the Guidelines (including existing appendices) will remain as originally drafted. A number of technical appendices will be developed to assist planning authorities in relation to noise assessment, monitoring and the setting of planning conditions. The proposed appendices will deal with Best Practice in relation to Noise Assessment; Monitoring and appropriate Noise Control post-construction; and Planning Conditions (drafts of these appendices have not been circulated to date).
Written submissions on the proposed revisions to the Guidelines were invited up to 21 February 2014. Following consideration of the submissions made during the consultation period, the revision to the Guidelines will be finalised and issued to planning authorities under Section 28 of the Planning and Development Act 2000 (as amended).
The draft revisions to the Guidelines focus primarily on the issues of noise (including set back distances) and shadow flicker. The aim of the proposed amendments is to find the balance between the protection of the residential amenity of communities in the vicinity of wind energy developments and facilitating the meeting of national renewable energy targets.
The draft revisions to the Guidelines propose a more stringent absolute noise limit (day and night) of 40dBA compared with the previous higher fixed daytime limit of 45dBA and 43dBA at night1. This limit is an outdoor limit2 which should not be exceeded at adjacent properties at any wind speed within the operational range of any turbine (i.e. from cut-in until maximum rated power level is reached). The limit applies to the combined sound level of all turbines in the area, irrespective of which wind farm development they may be associated with. The draft revisions to the Guidelines are underpinned by a report Commissioned from Marshall Day Acoustics. The Marshall Day report indicates that 40dBA is commonly used in different countries as an absolute limit and is considered in the lower end of the range of limits applied internationally.
The 40dBA noise limit applies to outdoor locations within the curtilage3 of properties adjacent to windfarms. Noise sensitive properties are defined as dwelling houses (including those which have planning permission but are not yet built), other buildings for long term residential use such as nursing/retirement homes, hospitals, schools, places of worship and areas of special amenity value.
Where there is a limited number of noise sensitive properties within the area between the wind energy development and where the 40dBA noise limit applies, it may be possible for the development to proceed provided the owner(s) of the relevant property is/are supportive of the development. The owner of the property must provide written confirmation that he/she has no objection to the proposed wind energy development and that he/she understands that his/her property may experience noise levels higher than the 40dBA noise limit.
The draft revisions to the Guidelines acknowledge that establishing a defined set back distance between turbines and sensitive receptors (such as dwellings) in relation to noise is not appropriate as the effects of noise from turbines may vary significantly due to topography, ground cover types and wind speed and direction. Notwithstanding this, a minimum separation distance of 500m between commercial scale wind turbines and the nearest point of the curtilage of any property in the vicinity is proposed. This is justified on the basis of providing for amenity considerations e.g. visual impact.
It should be noted that the separation distance does not apply to small scale wind energy developments generating energy primarily for onsite usage.
- Shadow Flicker
Under the Guidelines it was recommended that shadow flicker at properties within 500m should not exceed 30 hours per year or 30 minutes per day. The draft revisions to the Guidelines propose that a condition be attached to all future planning permissions for wind farms to ensure that there will be no shadow flicker at any dwelling within 10 rotor diameters of a wind turbine. It is also proposed that a Shadow Flicker Study for the purposes of modelling the impact of potential shadow flicker should accompany all planning applications for wind energy development. If shadow flicker does occur, the wind energy developer or operator will be required to take necessary measures, such as turbine shut down for the period necessary, to eliminate the shadow flicker.
The draft revisions state that the time period in which a property may be affected by shadow flicker is completely predictable from the relative locations of the wind turbine and the property. Modern wind turbines have the facility to measure sunlight levels and to reduce or stop turbine rotation if the conditions that would lead to shadow flicker at any neighbouring property occur. Therefore, with careful site design, appropriate mitigation and the use of appropriate equipment and software, no existing dwelling or other affected property should experience shadow flicker.
If a suitable shadow flicker prediction model indicates that there is potential for shadow flicker to occur at any affected property, then the draft revisions propose imposing an obligation on the developer to undertake a review of the site design. The review should consider the possible relocation of turbines with a view to eliminating or substantially reducing the occurrence of potential flicker. Following such a review, if shadow flicker is not eliminated then measures which provide for turbine shut down to eliminate shadow flicker should be clearly specified.
The Irish Wind Energy Association (IWEA) has stated that the existing Guidelines offer appropriate protection and do not need these additional revisions. It is concerned with the standardisation of planning conditions relating to noise and believes that setback should be determined by compliance with the appropriate noise limit. IWEA has further stated that the introduction of mandatory minimum distances could effectively prohibit a planning authority from considering wind energy development that may otherwise be acceptable.
The Irish Planning Institute has expressed support for the proposed revisions to the Guidelines stating that they present an opportunity to take national and international research and best practice into account along with development in wind technology. The Institute did however criticise the proposed revisions to the Guidelines as it believes that further studies on how wind farms affect the landscape need to be conducted.