Residential Wind Ordinance Proposed For Charlestown

The letter below was submitted to the Westerly Sun and Chariho Times by Ruth Platner and George Tremblay to explain the Residential Wind Ordinance proposed by the Planning Commission. The ordinance will have a public hearing before the Town Council on Monday, November 14, 2011.


Ordinances are written to accommodate competing interests.  In drafting its residential wind ordinance, Charlestown’s Planning Commission sought to balance the right of the applicant to harness wind energy with the right of neighbors to the safety and enjoyment of their property.  If we are to harness wind energy, we are compelled to seek compromises from both the applicant and neighbors.  Our objective is to make these compromises as balanced and benign as possible.  We write to publicize the rationale behind our decisions, in advance of the public hearing scheduled for Monday, Nov. 14, 2011 at 7 PM in the Charlestown Town Hall.

Setbacks:            Setbacks are intended to protect abutters against loss of property value, the intrusion of disturbing noises, and property damage from collapse of the tower. Minimum setback from each property line is 1x overall height of the turbine, plus the setback for accessory structures given in Zoning Ordinance 218-41.  In most zones, this minimum is turbine height plus 10’ along the side and rear property lines, and turbine height plus 40-50’ along the front.  The minimum setback shall be increased as necessary to limit noise at the property line to 35 decibels (dB) at night and 45 dB during the day (roughly the sound of quiet conversation and a humming refrigerator, respectively).  A good number of residential scale wind turbines meet these noise limits within 10 feet from the turbine.  Sound is cut by 6 dB each time the distance from the source is doubled, so 50 decibels at 10 feet is reduced to 44, 38, and 32 dB at 20, 40, and 80 feet, respectively.  Adjusting setback according to sound will encourage applicants to install wind turbines engineered to minimize noise.

Height:  If turbine height conforms with limits set for a primary structure, to which neighbors are accustomed (30-35’, per Zoning Ordinance 218-42), the application follows the routine permitting process.  For a turbine mounted directly on a residential structure, the height limitation is 10’ above the roof ridgeline, to permit clearance for moving parts.  Taller turbines are permitted (up to 125’), but only through application for a Special Use Permit, a process that notifies abutting neighbors, invites public comment, and offers opportunities for resolution of disputes before investments are made and work is begun.

Turbine Output:            Power consumption by the average homeowner could be met with a continuously operating wind generator of 1 kW output.  But wind turbines only function when wind speed is within a design range.  To compensate for idled turbine time, the ordinance allows for residential wind turbines with an output up to 20 kW, which is also suited for agricultural uses.

The above standards are intended to facilitate opportunities for residents to install a wind turbine, but also to accommodate neighbors by discouraging installations in the front yard, which neighbors might find unsightly, installations that make objectionable noise, and installations that interfere with enjoyment of the skyline.

Limitation to On-Site UseThrough net metering (electricity is supplied by the grid when the turbine is idled, and returned to the grid at the same price when the turbine is active), a reliable supply of power is assured at all times, at costs reduced in proportion to turbine output.  However, a recently enacted state law restricts net metering to no more than 125% of on-site consumption.  Additional output would be lost to the grid.

Power Sharing:  National Grid authorizes net metering only for electricity flowing through a single meter.  Accordingly, this ordinance does not include provisions for power sharing among neighbors using the same wind turbine.

Effects on Health and Welfare of NeighborsMajor objections to wind turbines include their physical dominance on the landscape, intrusion of noise disturbance on abutters, shadow flicker, interference with electromagnetic devices, and the fear of lost property values.  As turbine height rises above building height, little can be done to mitigate against the first, but the ordinance mitigates against disturbing noise by limiting the noise level at the property line.  Shadow flicker is seasonal, brief, and less a problem with residential sized turbines.  Mitigation against shadow flicker might be required of applicants seeking a special use permit for taller turbines.  Interference with electromagnetic devices is associated with movement of metal blades in close proximity to transmitters and receivers.  This has largely been eliminated by the substitution of plastics and other composite materials in blade technology.  The effect of residential-scale wind turbines on neighboring property values has been mitigated through setbacks requirements.

Application ProcessWe sought to minimize paperwork and expense to the applicant.  The Building Official is authorized to issue permits for any turbine that meets the height limits set for a primary structure.  Specifications provided by the manufacturer are accepted measures in the application.  To save on costs for electrical hook-up, no restriction is placed on proximity of the turbine to the residential structure.  Taller turbines are a greater imposition on neighbors, and therefore require a special use permit.  Since all of Charlestown must meet code for what is designated as a “High Wind Zone”, structural and electrical work must be certified by an engineer licensed in RI.  The proposed ordinance can be viewed on the Town’s website.

Ruth Platner and George Tremblay,
Subcommittee for drafting the ordinance
Charlestown Planning Commission