When people pay for deluxe accommodations, one thing they don’t expect for their money is to be cold. Hydronic radiant systems can serve with distinction in several areas of these properties, whether in group spaces like atria or dining rooms or smaller settings such as child care and guest baths. Heed some cautionary tips about proper construction and design process considerations, and then see where this approach can give you and future occupants a nice, warm feeling.

Resorts are not the first application for which one might select for in-floor hydronic radiant heat. Most often, private residences are the first application that comes to mind. In residences, in-floor radiant heat helps the home-owner decrease the thermostat setting while maintaining a comfortable living space. If in-floor heat is a good application for a private residence, then why not use it for a resort, too?

A resort provides more than guest room accommodations for its customers. There are many public areas, including a restaurant with dining rooms, a great room, a lounge, exercise room, arcade/game room, lobby, atrium, meeting rooms, ballroom, spa, child care room, and a swimming pool with hot tub. The back-of-house areas include a laundry facility, kitchen, various offices, wine storage, electrical room, telephone equipment room, water room, and mechanical room. A resort represents a microcosm of a city, with multiple services to meet the guest’s needs.

Traditionally, a full-service resort relies on an airside system with chilled water and hot water coils. The system may take the form of AHUs with fancoils in the guest rooms. But take another look at the various areas in a resort. Can they be heated with an in-floor hydronic radiant system? What are the pros and cons to using in-floor heat in these areas?

Whether the project is a new building or an addition to an existing building, resorts meeting the following criteria may find good applications for in-floor radiant heat.

Most projects install the required insulation and insulated-glass windows per local energy codes or current ASHRAE Standard 90.1. This level of insulation is required to realize the benefits of in-floor hydronic radiant heat. Resorts with spaces which require a minimal amount of cooling or no mechanical cooling present a good opportunity for radiant heat applications because there is no need for an additional cooling system. A resort with large open spaces or spaces with high ceilings is ideal because the radiant heat warms at the occupant level. Without completely ignoring costs, a project can benefit from in-floor radiant heat if the cost trade-offs allow some increase in installation costs for greater guest comfort.

In-floor radiant heat is not a good application for all situations. It has its drawbacks even in areas where it seems well-suited. Consider the specifics of each applicable area within the resort.

The Lobby and Great Room

The lobby and great room are transient areas that reflect the feel of the entire resort. Consider in-floor radiant heat for these locations. The spaces are large and welcoming with high ceilings and hard surfaces. Great rooms and lobbies are places for people to gather and sit for a time.

An even distribution of heat at the floor level can make the rooms cozy and inviting. Establish zones according to proximity to the exterior, fenestration, and use of space. These are spaces in which quick responding temperature change is not critical.

The Atrium

The atrium is an area that tends to feel colder than more intimate spaces during the winter months. Atriums have special mechanical considerations that make it a challenge to provide a comfortable space for individuals wishing to take advantage of the beauty of the space. In-floor radiant heat can provide the warmth for the occupants without interfering with the smoke exhaust requirements necessary for atrium spaces.

FIGURE 1. An example of a typical in-floor radiant tubing installation for concrete slab. (Image courtesy of Uponor.)

The Dining Room

A dining room is not normally a space that an owner would want warmer. However, in a heating dominated climate, in-floor radiant heat at the perimeter of a dining room with extensive exterior glass is an application to consider. In-floor heat eliminates the baseboard system that can make table arrangements difficult. It can eliminate the air movement onto the diners from an overhead diffuser.

A dining room, like all seating spaces, can cool off considerably when lightly occupied and can heat up quickly when full. An in-floor system with indoor and outdoor temperature sensors tied into a building EMS can provide a comfortable space when needed and not operate when not needed. One trade-off for this scenario is that an in-floor system does not change temperatures quickly. Experience and timing are key factors to keeping the diners comfortable.

Child Care Rooms

Child care rooms are good places to install in-floor radiant heat, especially when the rooms are located along an exterior wall. The temperature of the floor can be controlled for the comfort of the children and adults occupying the space. A warm floor provides a comfortable surface for the children to crawl and play. This application should include floor temperature sensors in combination with internal thermostats to regulate the temperature of the floor. When connected to the interior thermostat, the floor sensors serve as high-temperature limits on the floor.

The Guestroom

The guestroom bathrooms, like residential bathrooms, are spaces where a warm floor on a cold day is much appreciated. In-floor radiant heat and a radiant towel rack in a bathroom provide luxury to resort accommodations. Bathrooms with constant exhaust are good applications for an in-floor radiant system. The sensible heat from the floor works with the exhaust to keep the space dry.

General Benefits

One of the positive aspects of using in-floor radiant heat is the possible energy savings over traditional airside equipment. There is the potential to use less electric energy. Since fans are not used to convey warm air to the occupants, airflow requirements can be reduced to the amount necessary for ventilation purposes. Less air to move saves energy. Zones heated with in-floor radiant heat will typically have lower thermostat settings. Occupants will still be comfortable due to the nature of radiant heat.

The savings depend upon the project and cost of energy in a given location. Review the facts of the energy costs for the local area and the applicable costs of the intended design to determine any savings. A good energy model can help with this determination.

An side-effect of an in-floor system is the control of allergens. The system does not have a moving airstream in which dust and other allergens become entrained and get transported throughout a room or rooms.

Radiant heat is comfortable. Air does not blow on occupants; instead, an even heat radiates from the floor to the occupants and furnishings.

Radiant systems operate quietly. In a hydronic in-floor radiant system, water moves through tubes under a floor or in a slab, and an occupant cannot hear any of the moving parts associated with an in-floor radiant system.

Since there are no baseboard radiators or registers, the room furnishings can be freely moved around without affecting the occupants or the heating system.

For a project with boilers serving hot water coils, a system using in-floor hydronic radiant heat can add value to the project by making additional use of boilers whose primary purpose lies elsewhere.

Things to Watch Out For

For slab installations, repairing leaks means tearing out the entire installed zone or zones. This can be costly due to loss of use and cost of material and labor for the repair.

To achieve effective heat transfer for a good operating system, the possible choices of floor covering is limited. The best choice for floor covering over a radiant slab is hard surface and not carpeting.

Installing in-floor heat in commercial applications will generally cost more than traditional airside installations. It may take more time to find a qualified, experienced subcontractor, too.

There is a time lag associated with temperature changes in a slab with in-floor radiant heat. Slab temperature can not change quickly.

Water temperature is a critical consideration. Radiant in-floor systems typically use water between 85°F to 140°. The hot water should not exceed 140° and typically should be less. High water temperatures have an adverse affect on plastic tubing and on concrete.

For geographic areas that require cooling as well as heating, radiant in-floor heat only addresses a portion of the climatic needs for a tempered space. Cooling would still need to be provided for these spaces.

Construction Considerations

The success or failure of an in-floor radiant system depends on all aspects of the construction process: the design, installation, and maintenance. Failure to perform in any of these phases can have dramatic consequences.

During the design phase, consider applications that do not require fast transition from one temperature to another. In-floor radiant heat is best used in areas requiring steady moderate heating.

A properly performing in-floor radiant heat system requires good coordination among all the construction participants. The engineer and the architect need to communicate clearly with one another to ensure that adequate insulation is specified by the architect and shown on the construction drawings and details.

The designer must take great care in designing the whole system and taking into account the peculiarities of in-floor radiant vs. standard hot water heating coils. Some considerations for a successful design include the temperature of the heating water, the method of moving water from boiler to zone, the control of temperature within the zones, and the size and configuration of zones. The engineer should look carefully at the economics of the installation as well as the economics of the operation.

Installation and materials are critical for trouble-free start-up and operation, and in the past, copper and polybutylene were used. Copper can and will corrode over time if encased in concrete. Polybutylene will absorb oxygen through the tubing walls. The oxygen will cause problems like corrosion, which leads to leaks, which lead to failure of the system.

More recently, the most commonly used material for in-floor radiant heat loops is cross-linked polyethylene (PEX) tubing. PEX is a good candidate from a cost and material reactivity point of view as it does not react with concrete in slab installations. In addition, it is a durable material. Another material gaining in use is polypropylene copolymer tubing. The price of copper has reinforced the use of alternate materials, such as PEX and polypropylene copolymer tubing.

The material of the tubing, the method of installation, and the interplay between the two contribute significantly to the success or failure of in-floor radiant heat.

The expertise of the subcontractor can really add value to an in-floor hydronic radiant heating system. A subcontractor with substantial experience in both in-slab and floor-joist installations is more likely to provide a faster, well-organized installation. The experienced subcontractor is more likely to have protocols for protecting the tubing from damage such as nails for in-joist installations or kinked tubing in poured-slab installations.

The engineer and contractors can design and install the world’s best in-floor system, but it is the maintenance personnel who must keep the system at peak condition. Boiler maintenance, pump maintenance, regular visual inspection, complete logging of data, and reviewing the data are important aspects to maintaining an in-floor radiant system. The best maintenance records are only as good as the data reviews. Watching and responding to data trends can head off catastrophic failures of equipment.

Radiant Heat Can be a Good Choice

There are spaces within a resort that match well with in-floor radiant heat. The variety of physical spaces and guest expectations create many possible applications which provide high value for the project. As always, it is the responsibility of the design team to study the possibilities and review the pros, cons, costs, and savings to determine the best applications for in-floor radiant heat. ES