Measuring temperature and controlling it: a regulatory issue

Measuring the air temperature and managing its control is a matter of regulations. The building regulations insist on the instrumentation of measuring systems and on the supervision of all quantities and parameters of ventilation and air conditioning systems.

Do you know when the RITE regulations require measuring the air temperature of thermal installations?

The regulation, according to the document recognized as public and informative, Energy savings and recovery in air conditioning installations, establishes that:

• All thermal installations will have measuring devices (located in visible places accessible for reading) to monitor all quantities and values of the parameters that fundamentally intervene in their operation.

• If a physical quantity needs to be varied, it must be possible to measure it (the reading can be made using the signals from the control instruments).

• If the temperature is measured in water circuits, the sensor will penetrate the inside of the pipe or equipment through a sleeve (the permanent use of thermometers or contact probes is not allowed).

• In thermal installations with a nominal power greater than 70 kW, the minimum equipment for measuring devices will consist of supply and return collectors of a carrying fluid (a thermometer), expansion vessels (manometer), secondary circuits of pipes of a carrying fluid (thermometer in the return, one for each circuit), pumps (a manometer for reading the pressure difference between suction and discharge, one for each pump), chimneys (pyrometer or pyrostat), heat exchangers, air-water batteries, air-air heat recovery systems, and air treatment units (permanent measurement of the air temperatures in supply, return, and intake of outside air).

Logical indoor temperature standards according to RITE

To limit energy consumption, the regulation establishes logical indoor temperature standards and the requirements that thermal installations must comply with to ensure that their operation, throughout their useful life, is carried out with the maximum energy efficiency. This means ensuring safety, durability, and environmental protection.

Buildings used for administrative, commercial, and public gathering purposes (cultural, restaurants, transport, etc.), for reasons of energy savings, must limit temperature conditions inside. Thus, the air temperature in heated rooms shall not exceed 21 °C, and the air temperature in cooled rooms shall not be less than 26 °C (if, in both cases, conventional energy is required for the generation of heat/cold by the heating/cooling system). The previous temperature conditions will be related to maintaining a relative humidity between 30% and 70%.

When energy for heating or cooling the air is not necessary, the values will be governed exclusively by comfort criteria. In addition, those premises that justify the need to maintain special environmental conditions or have special regulations that decree this are exempt from complying with such temperature limitations.

Measuring temperature is essential in periodic inspection processes

The action of measuring temperature is key when carrying out the periodic inspections that thermal installations must undergo throughout their useful life. Buildings and premises used for administrative, commercial, and public gathering purposes (which must subscribe to a maintenance contract with an authorized company), according to Article 26 of RITE, are obliged to carry out a periodic verification of compliance with what is provided in this instruction (once during the summer season and once during the winter). It will be considered that a room meets the temperature limitation if the average temperature of the room does not exceed ± 1 °C of the indicated temperature limits. The measurement must be made in compliance with the following requirements:

• A measurement of the air temperature must be made at least every 100 m² of surface area, and at a height of 1.7 m above the ground.

• The largest number of measurements must coincide with the position of workstations. In the case of rooms not permanently occupied, the measurement will be taken at the center of the room (if only one measurement is performed).

• The precision of the measuring instrument will be at least ± 0.5 °C.