![Holland - Home of the heated sidewalks](https://upload.wikimedia.org/wikipedia/commons/3/36/Holland_-_Home_of_the_heated_sidewalks.jpg)
A snowmelt system prevents the build-up of snow and ice on cycleways,
walkway
In American English, walkway is a composite or umbrella term for all engineered surfaces or structures which support the use of trails.
''The New Oxford American Dictionary'' also defines a walkway as "a passage or path for walking along, esp. a ...
s,
patio
A patio (, from es, patio ; "courtyard", "forecourt", "yard", "little garden") is an outdoor space generally used for dining or recreation that adjoins a structure and is typically paved. In Australia the term is expanded to include roofed stru ...
s and roadways, or more economically, only a portion of the area such as a pair of -wide tire tracks on a
driveway
A driveway (also called ''drive'' in UK English) is a type of private road for local access to one or a small group of structures, and is owned and maintained by an individual or group.
Driveways rarely have traffic lights, but some that bear ...
or a center portion of a
sidewalk
A sidewalk (North American English), pavement (British English), footpath in Australia, India, New Zealand and Ireland, or footway, is a path along the side of a street, street, highway, terminals. Usually constructed of concrete, pavers, brick ...
, etc. It is also used to keep entire driveways and patios snow free in snow prone climates. The "snow melt" system is designed to function during a storm to improve safety and eliminate winter maintenance labor including shoveling, plowing snow and spreading de-icing salt or traction grit (sand). A snowmelt system may extend the life of the concrete, asphalt or under pavers by eliminating the use of
salts
In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...
or other
de-icing
Deicing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only deice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or preve ...
chemicals, and physical damage from
winter service vehicle
A winter service vehicle (WSV), or snow removal vehicle, is a vehicle specially designed or adapted to clear thoroughfares of ice and snow. Winter service vehicles are usually based on a dump truck chassis, with adaptations allowing them to carr ...
s. Many systems are fully automatic and require no human input to maintain a snow/ice-free horizontal surface.
Systems are available in three broad types based on the heat source: electric resistance heat, heat from a conventional boiler (or furnace), or geothermal heat
hydronically (in a fluid). Arguably, electric snowmelt systems requires less maintenance than hydronic snowmelt systems because there are minimal moving parts and no corroding agents. However, electric snowmelt systems tend to be much more expensive to operate.
Most new snowmelt systems operate in conjunction with an automatic activation device that will turn the system on when it senses
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
and freezing temperatures, and turn the system off when temperatures are above freezing. These types of devices ensure the system is only active during useful periods and reduce energy waste. A high-limit thermostat further increases efficiency when installed in conjunction with the automatic snow melt controller to temporarily disable the system once the slab/surface has reached a sufficient snow melting temperature. Some building codes require the high-limit thermostat to prevent energy waste. Total environmental impact depends on the energy source used.
Electric snowmelt systems
Electric snowmelt systems are composed of three basic components: heating cable, a control unit and an activation device.
The heating cable is built to withstand harsh conditions to make it suitable for outdoor usage. The cable should be listed to UL standards by a
Nationally Recognized Testing Laboratory
Nationally Recognized Testing Laboratory is the term used by the United States Occupational Safety and Health Administration to identify third-party organizations that have the necessary qualifications to perform safety testing and certification ...
and many consist of a single or dual conductor with a protective coating and/or insulation. Many cables are rated at and produce 6–50 watts per foot. Power per area is determined by
heating element
A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is independe ...
spacing.
The control units are typically wall-mounted control panels and can be mounted in a NEMA enclosure. Control units vary by technology by using line and load terminal blocks, relays, activation terminals, transformers, as well as monitoring electronics.
![Grooving closeup](https://upload.wikimedia.org/wikipedia/commons/d/d2/Grooving_closeup.jpg)
In recent years a new technology
has been developed to address melting snow on asphalt surfaces. Although asphalt pavements are the most common pavement type worldwide, there is no accepted heating solution for this infrastructure class for melting snow and preventing ice formation at the ride-surface. This novel methodology is utilizing electric ribbon technology as a suitable heating solution. A new method was proposed to introduce ribbon heaters into the typical paving process in a practical manner, causing minimal disruption to the normal paving operations, that is potentially expandable to large areas. The advocated idea was to deploy ribbons after an asphalt concrete lift has been paved and compacted, and before paving and compacting the next asphalt concrete lifts. In this context, a special grooving machine was envisioned to make shallow channels in the asphalt for cradling each ribbon. Thus, the system survivability is guaranteed, with all ribbons protected against the maneuvering of trucks, paving equipment, and heavy rollers. Subsequently, the method was demonstrated through the full-scale construction of a heated road that included installing ribbons in-between asphalt concrete lifts. For this purpose, the protective ribbon channels were grooved with a customized milling machine.
Hydronic snowmelt systems
The heating element in a hydronic system is a closed-loop tubing or modular thermapanel system made of a flexible
polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
or
synthetic rubber
A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32-million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubbe ...
that circulates a mixture of hot water and
propylene glycol
Propylene glycol (IUPAC nomenclature, IUPAC name: propane-1,2-diol) is a viscous, colorless liquid, which is nearly odorless but possesses a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH.
Containing two Alcohol (chemistry), alcoho ...
(antifreeze). The fluid is warmed to temperatures of to to warm surrounding concrete/asphalt/concrete pavers and melt snow and ice. Mechanical system technology for hydronic snowmelt systems is based on the same technology as
radiant heating
Radiant heating and cooling is a category of HVAC technologies that exchange heat by both convection and radiation with the environments they are designed to heat or cool. There are many subcategories of radiant heating and cooling, including: ...
systems.
The most crucial part of a successful tube based hydronic heating system depends on proper tube spacing and layout. It is recommended to lay the tubes in a spiral or serpentine pattern to help distribute the heat evenly. Specification for spacing will vary between manufacturers. A faster rate of snowmelting will require closer spacing of tubing, typical spacing is 6-8". Another key factor is the amount of insulation used under the slab.
Hydronic tubes that are cast into concrete slabs will create an uneven heating pattern in the concrete thus causing uneven stresses to occur within the concrete slab. The use of high temperature fluid entering a very cold slab will create stress cracks and possible spalling of the concrete surface. Close tube spacing and a controlled slow increase in temperature will lessen the negative effects of a tube based system. Another method is to maintain a minimum slab temperature above freezing throughout the winter season.
An alternative to tube based systems is pre-insulated,
HDPE
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...
modular heat exchange thermal panel units. The HDPE modular panels fit pedestal mounted pavers (typically used on rooftop installations) in a modular grid layout of between 23.5" - 26" on center. They may also be used with any type of ground mounted, cast in place concrete or raised deck mounted pavers, wood or PVC decking.
![Heated pavement](https://upload.wikimedia.org/wikipedia/commons/6/63/Heated_pavement.jpg)
Like electric snowmelt systems, hydronic snowmelt systems may be installed in or beneath the base surface material (sand). The subgrade should be well compacted with an appropriate road base material that meets ICPI (International Concrete Paver Institute) or the paver manufacturer's guidelines before beginning tube or thermapanel installation. Uneven settlement may damage the system and provide a structurally weak pavement. Tubing can be fastened with cable ties to either the re-mesh,
rebar
Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a Tension (physics), tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concr ...
or stapled to below slab insulation. Insulated modular thermapanel systems do not require re-mesh or rebar and are laid out in pre-connected rows onto the compacted sub-base. When a modular thermapanel system is set under a concrete slab, re-mesh or rebar within the concrete monolith may be necessary.
Hydronic tubes should not be placed directly on top of solid
bedrock
In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface mater ...
; this will cause the heating tubes to conduct heat into the earth. Pre-insulated modular thermapanel systems can be laid directly on bedrock or a structural concrete base.
To comply with most paver manufacturers warranties and ICPI (International Concrete Paver Institute) specifications, up to 1" of bedding sand for the pavers should be used and shall not exceed a maximum of 1 1/2". This can be a challenge with tube and re-bar based systems as they typically require over 1 1/2" of bedding sand. Excessive bedding sand will cause the pavers to settle over time. The sand used for bedding and jointing should be clean concrete sand, free of clay, dirt, or foreign matter and should conform to ASTM C-33.
Modular, fluid thermal transfer panel systems provide full and even heat exchange with the entire paver or concrete area as opposed to the spacing required by a tube based system. Full coverage allows for the use of lower temperature fluid which lowers the operating cost and lessens the thermal impact to the pavement structure thus reducing the deterioration of the concrete surface. The surface also comes up to temperature and can be cooled quicker.
Modular snowmelt systems can also be used to collect solar thermal energy from the pavement on warm days for the heating of pools and domestic or industrial purposes. They may also be utilized to cool the pavement surface, particularly around swimming pools or on pedestal mounted rooftop paver terraces which get very hot due to the paver being uncoupled from the building thus creating a solar battery which in turn increases the
urban heat island
An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparen ...
effect in the immediate vicinity.
Operation costs
Operating costs vary by region, energy source (electric, gas,
propane
Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
, etc.) used and costs associated. The
has standards intended to achieve satisfactory results and to minimize energy consumption from over-sizing or over-designing a system. Systems are typically designed to produce 70–170
BTU
The British thermal unit (BTU or Btu) is a unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is also part of the United States customary units. The modern SI u ...
per square foot hour using ASHRAE guidelines by region. The time to melt snow from a surface varies by storm and how much power the system is designed to produce.
Activation devices
There are a number of activation devices used for snow melting applications. Some activators are a simple manual
timer
A timer is a specialized type of clock used for measuring specific time intervals.
Timers can be categorized into two main types.
The word "timer" is usually reserved for devices that counts down from a specified time interval, while devices th ...
that activate the system to stay on for a specified time period while others sense temperature and moisture or just temperature conditions to automatically activate the snow melt system. Automatic devices can be aerial-mounted, pavement mounted or gutter mounted. High-end activation devices feature adjustable temperature trigger points, adjustable delay off cycle, and upgradeable remote activation. The activation device enables the snowmelt system to run 100% automated.
Self-regulating trace heating cables automatically regulate the amount of heat supplied so that only those parts with temperatures below the set point are heated.
Careful placement of the sensors is important to have an effective result when using these activators. Activation moisture sensors should be placed in a location where they will effectively collect any moisture from a snow storm and in relatively close proximity to the area to be free of snow and ice. Temperature sensors are installed outside to sense the same temperature conditions that the surface that the snow melting system will experience. Other activators, such as manual timers or switches can be installed in a convenient location.
New installations
The installation of snow melt systems is accomplished during construction of the walkway or roadway with the spacing of the cables or tubing or the layout of the modular thermapanel rows based on the system design.
There should be a minimum of 3” and max 4” of substrate covering the electric heating cables for new concrete applications. Concrete mixture must not contain sharp stones as these may damage the cable. The concrete should be allowed to set for 30 days before the heating cables are turned on. For this reason, the best installation time is during summer months. There is no practical way to use electric cable systems with pedestal mounted pavers.
Tubing systems typically have the tubes attached to the structural reinforcement which are then aligned within the concrete slab using cribs or standoffs. There is no practical way to use tubing based systems with segmented pavers or pedestal mounted pavers. The only type of hydronic system currently commercially available for use with pedestal, platform or ground mounted pavers is a modular thermapanel type system.
System installation specifications beneath asphalt may vary between each manufacturer. The cable can be laid out on the base surface (usually a sand bed), and covered with 1/2" sand. The asphalt is then hand-shoveled onto the heating cable and base surface.
When installing a hydronic tube or thermapanel system beneath asphalt, a barrier of sand that meets the manufacturers specifications should be placed over the tubing or thermapanels and cold water should be pumped through the system to keep the plastic from melting.
Insulation below the cables or tubing is recommended, but not required. One-inch rigid insulation can be installed underneath the base surface, or it can be laid on the base surface and the heating cable can be secured on top of the insulation.
Some installations involve two layers of asphalt. For this installation, a base layer of asphalt (1" thick) is placed down first. Heating cables are then installed and secured to the surface of the base layer. Once the heating cables are installed, a second layer of asphalt is placed over the heating cables and the first layer, embedding the heating cables within the slab.
Installing a snowmelt system under brick pavers is achieved by placing the heating cables on the base surface over 1/2" of sand. The heating cables are then covered with 1/2" of sand and the pavers are installed as normal over the sand bed. When using a hydronic system, up to 1" of bedding sand shall be placed over the thermapanel units. Tubing is not recommended for segmented paving applications due to the need for excessive bedding sand.
Retrofit installations
Retrofit installations are possible with electric systems by cutting grooves 1" to 1" deep and between 1/4" and 3/8" wide into the asphalt or concrete, inserting the cables and sealing the grooves with backer rod and a special
caulking
Caulk or, less frequently, caulking is a material used to seal joints or seams against leakage in various structures and piping.
The oldest form of caulk consisted of fibrous materials driven into the wedge-shaped seams between boards on w ...
or sealant at the surface of the groove.
Portable heated snow mats for consumers
Within the past few years, heated snow melting mats have become available to retail consumers. These plug into a water-resistant electrical outlet, and can be laid on walkways, driveways, stairways, wheelchair ramps, and loading docks.
These heated mats consist of two layers of slip-resistant rubber with an intervening heating element, and can melt snow and ice in hours or minutes (depending on heat level and snow level). The mats turn on below a preset temperature with an optional inline thermostat.
Notable installations
* Maxima Hospital, Eindhoven, The Netherlands.
* Truck Loading Docks, Eindhoven, The Netherlands.
* Under-road heating system to keep Europe’s highways ice-free
* Elevated
Central Artery
The Central Artery (officially the John F. Fitzgerald Expressway) is a section of freeway in downtown Boston, Massachusetts; it is designated as Interstate 93, US 1 and Route 3.
The original Artery, constructed in the 1950s, was named after ...
, Boston (disused and since demolished)
*
M4 motorway
The M4, originally the London-South Wales Motorway, is a motorway in the United Kingdom running from west London to southwest Wales. The English section to the Severn Bridge was constructed between 1961 and 1971; the Welsh element was largely ...
, West London (disused)
*
Schweitzer Mountain
Schweitzer Mountain Resort is a ski resort in the northwest United States in northern Idaho, northwest of Sandpoint. Located in Bonner County in the Selkirk Mountains, it overlooks Lake Pend Oreille to the southeast with views of the Bitter ...
roads, Idaho
* Former personal residence of
Peter Lawwell
Peter Lawwell (born 27 May 1959) is the former chief executive of Scottish Premiership club Celtic. He retired in June 2021 from his role as CEO. He was announced as successor to current Celtic chairman Ian Bankier on 2nd December 2022 and will ...
, driveway
*
Updown Court
Updown Court is a Californian style residence situated in the village of Windlesham in Surrey, England. The 103-room mansion has of landscaped gardens and private woodland.Conradi, Peter and Davies, Helen (2007)The most expensive house in Britain ...
driveway, England
*
Bill Gates' house
Bill Gates designed and owns a mansion that overlooks Lake Washington in Medina, Washington. The mansion incorporates technology in its design.
In 2009, property taxes were reported to be US$1.063 million on a total assessed value of US$147. ...
, driveways
* Public sidewalks in
Reykjavík
Reykjavík ( ; ) is the capital and largest city of Iceland. It is located in southwestern Iceland, on the southern shore of Faxaflói bay. Its latitude is 64°08' N, making it the world's northernmost capital of a sovereign state. With a po ...
and
Akureyri
Akureyri (, locally ) is a town in northern Iceland. It is Iceland's fifth-largest municipality, after Reykjavík, Hafnarfjörður, Reykjanesbær and Kópavogur, and the largest town outside Iceland's more populated southwest corner.
Nicknamed ...
, Iceland
*
Karl Johans gate
Karl Johans gate is the main street of the city of Oslo, Norway. The street was named in honor of King Charles III John, who was also King of Sweden as Charles XIV John.
Karl Johans gate is a composite of several older streets that used to be s ...
and various public sidewalks in
Oslo
Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of ...
, Norway
* Public streets and sidewalks in
Holland, Michigan
Holland is a city in the western region of the Lower Peninsula of the U.S. state of Michigan. It is situated near the eastern shore of Lake Michigan on Lake Macatawa, which is fed by the Macatawa River (formerly known locally as the Black River). ...
* Public sidewalk in
Oak Park, Illinois
Oak Park is a village in Cook County, Illinois, adjacent to Chicago. It is the 29th-most populous municipality in Illinois with a population of 54,583 as of the 2020 U.S. Census estimate. Oak Park was first settled in 1835 and later incorporated in ...
*
National Research Council National Research Council may refer to:
* National Research Council (Canada), sponsoring research and development
* National Research Council (Italy), scientific and technological research, Rome
* National Research Council (United States), part of ...
entrance sidewalk,
Saskatoon
Saskatoon () is the largest city in the Provinces and territories of Canada, Canadian province of Saskatchewan. It straddles a bend in the South Saskatchewan River in the central region of the province. It is located along the Trans-Canada Hig ...
,
Saskatchewan
Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...
* CN Tower, main pod roof (Toronto, Canada)
* Several streets in the city center of
Helsinki
Helsinki ( or ; ; sv, Helsingfors, ) is the Capital city, capital, primate city, primate, and List of cities and towns in Finland, most populous city of Finland. Located on the shore of the Gulf of Finland, it is the seat of the region of U ...
, Finland
See also
*
Hypocaust
A hypocaust ( la, hypocaustum) is a system of central heating in a building that produces and circulates hot air below the floor of a room, and may also warm the walls with a series of pipes through which the hot air passes. This air can warm th ...
*
Smart highway
Smart highways and smart roads are highways and roads that incorporate electronic technologies. They are used to improve the operation of connected and autonomous vehicles (CAVs), for traffic lights and street lighting, and for monitoring the cond ...
*
Snowmelter
A snow melter is a piece of snow removal equipment designed to melt snow using flame burners, hot water or both. The melt-water is discharged into a storm drain or onto the ground. Melting snow artificially helps keep roads, airport tarmacs and ...
*
Solar Roadways
Solar Roadways Incorporated is an American company based in Sandpoint, Idaho, aiming to develop solar-powered road panels to form a smart highway.
Their proof-of-concept technology is a hexagonal road panel that has a glass driving surface with ...
*
Trace heating
Electric heat tracing, heat tape or surface heating, is a system used to maintain or raise the temperature of pipes and vessels using heat tracing cables. Trace heating takes the form of an electrical heating element run in physical contact along ...
References
* Woodson, R. Dodge. Radiant Floor Heating. New York: McGraw-Hill, c. 1999.
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Snow removal