advanced search

Adding Value on the Home Front

Nov 1, 2007 12:00 PM, By Carlos Villalobos, Watt Stopper/Legrand

Vacancy and occupancy sensors specifically designed for home applications are now widely available

Many of today's homeowners are enthusiastic about energy-saving products, especially those that boast a quick payback. Vacancy and occupancy sensors are not only meeting this efficiency need, but also helping reach the latest energy code requirements, such as California's Title 24. Electrical contractors who select and install residential occupancy-based controls can add value to their projects and differentiate their services by offering customers a “green” solution.

The variety of controls developed specifically for residential applications has increased dramatically in response to this growing demand. And consumers are enthusiastically accepting these products, as evidenced by the Home Lighting Control Alliance, a Warrenton, Va.- based self-funded, member-driven consortium of lighting control manufacturers, systems integrators, and industry support organizations, which reported that the adoption rate for lighting control in new, single-family homes had tripled in a single year.

Once contractors understand the expanded range of available control strategies and options, they can confidently install and set up occupancy-based controls throughout a home.

Passive infrared sensors

Residential occupancy-based controls are typically passive infrared (PIR) devices that fit into a single-gang box and simply replace a traditional wall switch. Sensors include the basic toggle function, but also add automated control features based on occupancy. They work by sensing body heat — contrasted against the cooler surroundings. Each sensor includes a lens that is used to determine the coverage area and sensitivity for that particular device. A good-quality sensor can see a full 180° and sense a space of 600 to 900 square feet. However, care must be taken to locate a sensor within direct line of sight of the area it's intended to monitor.

Sensors save energy by turning lights off when no movement (occupancy) has been detected for a specific period of time, which is known as the time delay. Different length delays are appropriate for different applications. The goal in selecting a time delay is to maximize energy savings without compromising user safety or comfort. A long time delay, such as 30 minutes, works well in a bathroom where an occupant might take an extended bath or shower out of view of the sensor. A laundry room or hallway could use an even shorter delay. The key is to avoid false offs in spaces where there might be minimal movement when the area is occupied.

Wiring wall switch sensors is straightforward because they are self-contained devices. Most residential sensors require a neutral connection, which is an important safety feature, as it prevents the device from leaking current to ground. For retrofit applications without neutrals, safe 2-wire devices are available but will be limited to controlling incandescent loads. All controls should be properly grounded, and specific load requirements should be confirmed before installation. Residential wall switch sensors are available to control small motor loads as well as lighting loads, including incandescent, low voltage with magnetic or electronic transformers, and linear or compact fluorescents.

Occupancy sensors vs. vacancy sensors

The first step in choosing the best product for a particular application is determining the control strategy appropriate to the space in which it will be used. Residential occupancy-based controls are named based on their mode of operation, falling into one of two categories: occupancy sensors or vacancy sensors.

Occupancy sensors automatically turn the lights on as soon as they detect occupancy. When a time delay has been reached without further occupancy being detected, they turn the lights off. If desired, occupancy sensors may be manually overridden to keep lighting off as needed.

Vacancy sensors detect when a space is vacant and turn the lights off following a time delay. They feature manual-on operation, which has several benefits. Because they don't automatically turn lights on when motion is detected they are ideal for the many applications that don't routinely require lights to be on when the space is occupied. Vacancy sensors can maximize energy savings for many residential applications by ensuring the lights are not turned on unless they are needed. Households with pets are good candidates for vacancy control as there is no possibility of a false on.

The California Energy Commission understands the energy-saving potential of manual-on sensors. Title 24 dictates this control option for residential projects if builders are using controls in lieu of high-efficacy light sources in certain applications. Contractors should note that some sensors can operate either as occupancy or vacancy sensors based on a configuration option.

Want to use this article? Click here for options!

© 2012 Penton Business Media, Inc.

---

Acceptable Use Policy blog comments powered by Disqus

Browse Back Issues Select an Issue EC&M Magazine | April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 1, 2009 December 2008 November 2008 October 1, 2008 September 2008 August 2008 July 2008 June 1, 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 1, 2006 May 1, 2006 April 2006 March 1, 2006 February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005 February 2005 January 2005 December 2004 November 2004 October 2004 September 2004 August 2004 July 2004 June 2004 May 2004 April 2004 March 2004 February 1, 2004 January 1, 2004 December 1, 2003 November 1, 2003 October 1, 2003 September 1, 2003 August 1, 2003 July 1, 2003 June 1, 2003 May 1, 2003 April 1, 2003 March 1, 2003 February 1, 2003 January 1, 2003 December 1, 2002 November 1, 2002 October 1, 2002 September 1, 2002 August 1, 2002 July 1, 2002 June 1, 2002 May 1, 2002 April 1, 2002 March 1, 2002 February 1, 2002 January 1, 2002 December 1, 2001 November 1, 2001 October 1, 2001 September 1, 2001 August 1, 2001 July 1, 2001 June 1, 2001 May 1, 2001 April 1, 2001 March 1, 2001 February 1, 2001 February 1, 1995 January 1, 2001 December 1, 2000 November 1, 2000 October 1, 2000 September 1, 2000 August 1, 2000 July 1, 2000 June 1, 2000 May 1, 2000 April 1, 2000 March 1, 2000 February 1, 2000 January 1, 2000 December 1, 1999 November 1, 1999 October 1, 1999 September 1, 1999 August 1, 1999 July 1, 1999 June 1, 1999 May 1, 1999 April 1, 1999 March 1, 1999 February 1, 1999 January 1, 1999 December 1, 1998 November 1, 1998 October 1, 1998 September 1, 1998 August 1, 1998 July 1, 1998 June 1, 1998 May 1, 1998 April 1, 1998 March 1, 1998 February 1, 1998 January 1, 1998 December 1, 1997 November 1, 1997 December 1, 1996 November 1, 1996 October 1, 1996 September 1, 1996 August 1, 1996 July 1, 1996 June 1, 1996 May 1, 1996 April 1, 1996 March 1, 1996 February 1, 1996 January 1, 1996 December 1, 1995 November 30, 1995 November 1, 1995 October 1, 1995 September 1, 1995 August 1, 1995 July 1, 1995 June 1, 1995 May 1, 1995 April 1, 1995 March 1, 1995

browse e-newsletters