Environmental Control Systems (PECS) with the functions of heating, cooling, ventilation, lighting and acoustics has advantages of controlling the localized environment at occupant’s workstation by their preference instead of conditioning an entire room. This improves personal comfort, health and energy efficiency of the entire heating, ventilation and air-conditioning (HVAC) system substantially. Personalized ventilation will also protect against cross contaminations, which are critical in open plan offices and work places with close distance.
There will in the future be an increasing interest and market for PECS as buildings will need to be pandemic-proofed. The application is for work places with mainly sedentary activity like offices (open plan, banks, control centres, etc.). Due to the COVID-19 pandemic, where many people worked at home, there will be an increase in home working places where PECS may be a solution as well.
There are large differences among occupants in terms of thermal condition preference, air movement preference, clothing level, activity, ventilation and air quality preference and also their physiological and psychological responses. The climate satisfaction of most occupants can be improved significantly by allowing each occupant to control their micro-environment personally. Therefore, Personalised Environmental Control Systems (PECS) with the functions of heating, cooling, ventilation, lighting and acoustic are designed to control the local climate conditions surrounding the occupant’s workstation by their preference instead of conditioning an entire room. In this regard, PECS has obviously advantages in large spaces such as open plan offices where it substantially improves local climate comfort directly and the energy efficiency of the entire system. Generally, PECS is more energy-efficient and economical than conventional HVAC because it can extend the standardized temperature range related to HVAC, which is specified in ISO 7730. Previous studies pointed out that with the suitable application of PECS, it is possible to achieve comfort (dissatisfaction lower than 20%) in a temperature range between 18 and 32 ◦C. Moreover, thermal optimization of the personal workstation not only improves the quality of the inhaled air and protects the health of occupants, but also has potential to improve the productivity of the occupants.
Most well-known is individual task lighting and individual “masking” of noise by using headphones; but several other opportunities will exist with individual systems. Most studies reported in literature have been focusing on thermal comfort and air quality.
These type of PECS can be classified into three categories according to its functions: heating PECS, cooling PECS, ventilation PECS, lighting PECS, acoustic PECS, and their combinations. Heating PECS can provide heat to the local body parts of the occupants using local heating devices through heated surfaces, radiant heaters and warm air [2]. In literature, there are several types of heating PECS including air sleeves, heated seats, foot heater, palm warmer, desk-mounted devices, and nozzle with movable panel [4]. Cooling PECS can cool the occupant through cooled surfaces, radiant cooling devices, and supply airflow directly or preconditioned air to the individual or multiple body parts of the occupant. Previous studies have included air sleeve, cooled seat, garment, radiant cooling panels, desktop-based devices, nozzle-based devices, radiant panels with fan operation. Ventilation PECS allows to supply fresh air or preconditioned air towards the breathing zone of the occupants in order to improve thermal comfort and perceived air quality. Desk-based devices, nozzle-based devices, mechanical fans, seats, and garment are in this category.
There are still other types of PECS installed on the horizontal or vertical room surfaces for conditioning or supplying air to a larger space than a table fan, such as personal ceiling fans or standing fans. However, at workstations in an open-space office, desk-mounted ventilation or cooling devices are more popular due to their high efficiency and flexible adjustment. In addition, foot heater could improve the overall thermal comfort of occupants, especially in cold environments. A previous study also indicated that there are many heating PECS that warms the lower body parts of the occupant by heating conduction or convection. However, only a few PECS aims to condition the lower body parts of the occupant. Overall, desk-mounted ventilation devices and local heating devices for feet and lower body parts are commonly used in workstations.
Most of the research until today has been focused on thermal comfort and indoor air quality/ventilation, but there are also potential benefits for individual control of lighting and use of noise masking. Artificial lighting that simulate daylighting can have health benefits. Also, different light colours during the day will have benefits for wellbeing and productivity.
The majority of the studies confirm that the use of PECS can result in significant HVAC system energy use savings (even though the values of possible energy savings given in the literature vary in a large range). However, several studies also point out that if PECS is not designed and operated correctly, there will be increased energy use instead of the intended energy savings. Since most of the studies focused on the thermal comfort and air quality aspects of PECS, there has been little focus on the power use of the PECS itself.
There is very little information in literature on how the general HVAC and lighting system shall be controlled together with PECS. The concept is that in spaces with PECS, the requirement to the general environment, which together would result in energy savings.
Objectives and Scope
The previous studies have shown that PECS improves occupants’ satisfaction with the indoor environment substantially. However, most of the studies were carried out under controlled conditions and long-term performance from real buildings is missing. There is also a gap in the knowledge and tools necessary to make these systems widely-applicable in buildings. Based on this:
The objective of the present annex is to establish design criteria and operation guidelines for PECS and to quantify the benefits regarding health, comfort and energy performance. This includes also control concepts and guidelines for operating PECS in spaces with general ambient systems for heating, cooling, ventilation, and lighting.
The scope of the present annex includes all types of PECS for local heating, cooling, ventilation, air cleaning, lighting, and acoustics. It includes desktop systems, which are mounted on desks or integrated in a furniture, chairs with heating/cooling and ventilation and other types that can be found. It also includes wearables, where heating, cooling, and ventilation are included in garments or devices attached to occupants’ body.
The subtasks are structured to address the objectives and scope of the annex and described further in the following parts of this text.