Which Way is the Wind Blowing on Small Wind Energy Systems?

Thomas W. Hildreth
Of Counsel, Corporate Department
Published: Portsmouth Herald
August 30, 2010

In the summer of 2007, New Hampshire Public Radio ran a story entitled “Local Zoning Laws Hinder Wind Power.”  (NHPR, 06/27/2007)

A year later, the Associated Press reported “Bill Supporting Residential Wind Turbines in NH Passes.” (A.P., 08/01/2008)

Two years later, it is hard to find examples of any residential wind turbines in the Seacoast.  In the four towns surveyed for this article – Portsmouth, Rye, Hampton and Exeter – municipal planners could not point to a single residential wind turbine in their communities.

Although the sluggish economy may make many reluctant to invest in a home wind energy system, energy costs remain stubbornly high, and tax credits for renewable energy systems have hardly ever been more generous.  According to “A New Hampshire Consumer’s Guide to Small Wind Electric Systems” published by the U.S. Department of Energy (the “DOE Guide”), a small wind energy system can lower your electricity bill by 50% to 90%, depending on local wind conditions.

Is there something else holding people back?

The law referred to in the 2008 A.P. story is codified at RSA 674:62-66, and governs small wind energy systems (SWES).  A SWES is essentially a wind turbine for home power consumption.  The SWES law was passed in 2008, and became effective July 11, 2009.  The SWES law builds on earlier legislation.  A 2002 enactment amended RSA 672:1 –the statute which declares the general purposes of New Hampshire’s local land use laws – to include this provision:

“`Z`oning ordinances should not unreasonably limit the installation of solar, wind, or other renewable energy systems or the building of structures that facilitate the collection of renewable energy, except where necessary to protect the public health, safety, and welfare.” 

The 2008 SWES law takes that concept one step further focusing solely on small wind power systems for homeowners.  The SWES law requires that ordinances or regulations adopted by municipalities to regulate the installation and operation of small wind energy systems not unreasonably limit such installations or unreasonably hinder their performance.  The SWES law also establishes some markers to define the boundaries of reasonableness.  The law defines unreasonable limits to include:

  • prohibiting SWES from all zoning districts;
  • restricting height through application of a generic height limitation that does not address SWES needs;
  • requiring set backs greater than 150% of the height of the wind turbine; and
  • setting a noise level limit lower than 55 decibels at the property line.

All four communities in our survey have added provisions to their zoning ordinances to address small wind energy systems.  The SWES ordinance provisions range from one page in Hampton to seven pages in Rye, but they all cover the same core requirements:  what zoning districts can play host to a SWES; how much power can a SWES generate; how tall can the system be; what are the set back requirements and noise limitations; and the like.  The following chart provides a comparison of the four SWES ordinances on some of these issues.






Permitted zones

Permitted accessory use in all zones

OK in all zones except conservation and recreation


Permitted in all zones


100 kilowatts or smaller

60 kilowatts or smaller

100 kilowatts or smaller

60 kilowatts or smaller

Height limit

Smaller of 150’ or trees + 35’


Smaller of 125’ or trees + 35’



Variable, from 110%-150%


System height +15’



60 dbA

55 dbA

50 dbA

60 dbA


Planning Board approval + building permit

Planning Board approval + building permit

Building permit

Zoning Board approval + building permit


Despite the legislative encouragement of small wind energy systems, including the many local ordinances that have been passed in the wake of the 2008 state-wide legislation, it may be the case that such ordinances actually make it harder, not easier, to site a small wind energy system.

Before the advent of these local SWES by-laws, many local zoning ordinances carved out generous exemptions from their across-the-board 35’ height limit for most structures.  Often exempted from such height limits are a laundry list of things such as:  church steeples, bell towers, grain elevators, flagpoles, windmills, other unoccupied structures, and the like.  In some cases, then, the new SWES ordinances add height limitations where no limit was previously applied.

Similarly, many of the new SWES ordinances have excessive set back requirements, sometimes referred to as “fall zones.”  Here many ordinance drafters fall prey to, what I call, “the fallacy of the fall zone.”  Small home wind turbines that are constructed and installed in accordance with manufacturer’s recommendations do not fall over any more frequently than similar structures of similar size – like the light poles in and around the Portsmouth traffic circle.  In fact, they pose much less danger from falling or collapse than the 100+ foot maple tree that might straddle the common border between one neighbor and another.  Imagine if the builders of the North Church in Portsmouth had to comply with such set back requirements with respect to the soaring steeple that towers over Market Square.

To understand the impact of the excessive set back requirements, consider, for example, a proposed SWES that would be 100’ tall (from the tip of a blade measured at its maximum height to the ground) in Exeter, which requires a 150% set back.  The 100’ SWES would require a 150’ set back.  A circle centered on the SWES with a radius of 150’ would take up more than 70,000 square feet, which is more than 1.5 acres of land.  There is little practical reason, from a public safety point of view, why such a structure could not be closer to a property line than that.

RSA 674:66 requires that a building inspector provide formal notice to abutters upon receipt of an application for a building permit to construct a SWES.  The state statute gives abutters a 30 day comment period before a building permit can be issued.  Because of that state statute, even in towns that don’t require any review and approval by either the planning board or the zoning board (such as the Town of Hampton), abutters have a role in the process.  Accordingly, anyone considering a small home wind energy system would be well advised to talk with their neighbors well in advance of submitting a formal application in order to take their input into account early in the planning process.

Ultimately, whether the new state law and the corresponding local regulations further or hinder the deployment of small wind energy systems, the major limiting factor may simply be the amount of land required and the free space surrounding a SWES for its optimal operation.

The Rye SWES ordinance is the only one of the four surveyed that includes an express appreciation for the physics required for a well functioning SWES.  The Rye ordinance states:

In reviewing the proposed height in an application for a conditional use permit, the Planning Board may consider the ‘rule of thumb’ that the bottom of rotor blades should be at least 30’ above any obstruction within 300’.  The Planning Board may also consider that increased tower height may yield high returns on power production.”

The “30’ above any obstruction within 300’” is a good starting point to begin to think about how high a home wind turbine would need to be for optimum performance.  With the average height of a single family home approximately 30’, if the wind turbine will be within 300’ of your home, then the bottom of the rotor blade would need to be at least 60’ above the ground.  The DOE Guide suggests that most small wind energy systems will have rotor blade diameters of anywhere from one meter to seven meters (approximately three feet to 22 feet).  With a house 30’ tall and a turbine within 300’ of the house so that the bottom of the rotor blade is never closer than 60’ to the ground, if you have a 20’ diameter rotor then the overall height of your system would be 80’.  Trees on your property which are taller than your house would drive that number higher.

The DOE Guide provides very helpful information on the effect of wind being obstructed by buildings and trees, creating areas of turbulent flow and advising on where and how high to site a wind turbine for optimum operation in relation to such nearby obstructions.

Until we see some actual applications for small home wind energy systems submitted under the recently promulgated SWES ordinances, it will be hard to know the full impact of the ordinances on such initiatives.  In the meantime, it can be hoped that the building inspectors, zoning boards and planning boards who hear such applications will consider the over-arching objective of encouraging such systems and apply their local ordinances with a reasonable touch.  Otherwise the wind which continues to blow across our seacoast may only be for the benefit of the sailors and kite flyers among us.