Hotel furniture assembly: a guide to optimal temperature and humidity conditions

The opening of a hotel facility for the winter or summer season very often brings with it the need to install hotel furniture in adverse conditions. Seasons of the year, and construction work affect the level of temperature and humidity in the furnished rooms. As we all know, furniture and other furnishings “don’t like” humidity, but not everyone knows that they don’t like rapid changes in temperature either. But before we determine what is the level of moisture that furniture does not like, let’s start by systematizing the problem.

With regard to construction and materials science, which we are dealing with in this article, we most often talk about the concept of humidity in the context of the humidity of the air and the humidity of individual materials or building envelopes. Each time, this humidity is given as a percentage, but refers to two completely different parameters. In the case of air, we talk about relative humidity, and in the case of materials, we talk about mass humidity.

Relative humidity

Relative humidity, which we use to define air humidity (after Wikipedia), is the ratio, expressed as a percentage, of the partial pressure of water vapor contained in air to the saturated vapor pressure of water vapor over a flat surface of pure water at the same temperature. The definition is not easy to understand, but it is enough for us to know that relative humidity as a parameter is only comparable when the air temperature is the same.

In practice, what this means for us is that a given relative humidity expressed as a percentage for different temperatures means a different mass of water vapor in the same volume of air. For example, 1 m³ of air at 0°C and a relative humidity of 75% contains 3.5 grams of water vapor. When the same 1 m³ of air is heated to 20°C, its relative humidity will be only 20%.

The conclusion from this is that we must remember that all normative relative humidity in the broader construction industry refers to a temperature of 20°C (unless another temperature is specified). So if we measure the permissible level of humidity at a lower temperature than 20°C then the normative permissible humidity will be higher, and if at a higher temperature then it will be lower.

The acceptable relative humidity of indoor air at 20°C should be between 30-65%. The optimum humidity for the same temperature at which humans feel best is 45-60%. Such humidity is not only good for human health, but also beneficial for clothes, floors, furniture and books.The minimum permissible value of air humidity in apartments is specified in the Polish standard PN-78/B-03421 at 30%.

Bulk moisture content

MASS MOISTURE, is a much easier parameter to compare, because it expresses as a percentage the ratio of the mass of water contained in a given material to the mass of that material.

The classification of the mass moisture level of the walls, which, due to direct contact with most hotel furniture, has a key influence, is as follows:

• Up to 2.5% – dry walls, humidity may be a result of air humidity and our usage
• 2.5 – 5.0 % – slightly damp walls
• 5.0 – 8.0 % – damp walls (from this threshold, industrial dehumidification indicated)
• 8- 12 % – walls severely dampened
• above 12% – wet walls

A wall that is not dry will give up excess moisture to its surroundings by natural processes. If the wall’s surroundings are furniture directly adjacent to it, this process will mean the direct transfer of moisture from the walls to the furniture and a significant extension of the process of draining excess moisture into the environment. The result is “swelling” of the furniture and the appearance of mold on the walls.

Now that we know more about humidity and its permissible levels, let’s check out what manufacturers of the basic furniture material, which is laminated furniture board, say on the subject. Egger, one of the main board manufacturers on the European market, defines the temperature and humidity conditions for its standard furniture boards in this way (quote from the certificate for P2 board): “Moisture conditions for furniture boards corresponding to use class 1 of the EN 1995-1-1:2004 standard, characterized by a moisture content in the material corresponding to a temperature of 20°C and a relative humidity of the surrounding air exceeding 65% for only a few weeks during the year.”

In the considered case of furniture installation in a new or renovated hotel facility, we must assume that the relative humidity at 20°C must not briefly exceed 65%, and we must keep an eye on these parameters even after furniture installation, especially if the commissioning of the facility does not immediately follow.

Furniture assembled in high humidity conditions can be exposed to:

• HDF bend in the back of the cabinets
• Mildew, most often of items standing/hanging close to/on the wall
• “swelling” i.e. change in volume under the influence of moisture

As we mentioned, this especially applies to furniture and fixtures standing against walls, inserted into alcoves, hung on walls, especially freshly painted, or wallpapered. In particular, these are the panels of dressing tables and mirrors, headboards, closets.

Temperature stability

Another parameter that greatly affects the condition of furniture is temperature stability. Furniture is “not afraid” of a constant temperature, but of its changes. And dangerous for them is both a rapid change in temperature downward and upward.

If the temperature drops rapidly (as in an unheated building during a frost), dew condenses on all solids, which, in the case of furniture, runs down the laminated surfaces of the panels to soak into the raw or edged edges of the panels. Equally or even more dangerous is the rapid rise in temperature (as when full heating is turned on in a building that has not previously been heated) when there is rapid drying of the elements directly exposed to the heating, while moisture persists in the interior or sheltered elements. The result is irreversible pilling and wicking of furniture elements.

Then there may be, first of all, a change in shape, bending of cabinet doors, closet panels. All those large surface elements that, by design, must be thin. Interestingly, these changes can occur from a few to even a few tens of days after the installation of furniture, and sometimes even after opening the object, the change in temperature can so change the shape of the element that it is possible to tear a solidly attached panel from the wall.

Applications

• Installation of furniture in conditions not conducive to this is caused solely by the need to put the facility into operation as soon as possible.
• Despite the time pressure accompanying the pre-opening of the facility, we strongly do not recommend installing furniture under the described adverse conditions. The costs and problems resulting from unprepared rooms far exceed the “time saved”.
• Our assumed conditions for furniture assembly are: Temperature above 18 °C

Air humidity

• At a room air temperature of 18°C – up to 68%
• at a room air temperature of 20°C – up to 60%
• at a room air temperature of 22°C – up to 55%
• At a room air temperature of 30°C – up to 32%
• MASS MOISTURE: Moisture content of walls less than 4%.

The problems described apply to furniture made in standard furniture boards. Moisture-resistant furniture, or furniture made entirely of mdf, may behave differently, but it does not make economic sense to use them. It is better to prepare the schedule of works so that the installation is possible in favorable conditions.

Summary (abridged version)

Assembling hotel furniture during the winter or summer season presents challenges due to weather conditions that affect humidity and temperature. Relative humidity, given as a percentage, is a measure of the amount of water vapor in the air and is directly related to temperature. The ideal indoor relative humidity is 30-65% at 20°C, which is conducive to both human health and the condition of furniture and other furnishings. Mass humidity, on the other hand, is the ratio of the weight of water in a material to its total weight, with values above 2.5% likely to indicate moisture.

When assembling furniture, it is important to maintain a stable and appropriate temperature, as furniture reacts badly to sudden changes in temperature. The recommended conditions are a temperature above 18°C and controlled humidity, which varies depending on the air temperature – at 18°C up to 68%, and at 30°C up to 32%. The humidity of the walls should be below 4%. It is recommended to avoid installation in unsuitable conditions, as this can lead to permanent damage to the furniture, such as warping or molding. Instead of taking risks, it is better to plan the work so that the conditions are optimal for assembly.