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HVAC Building Controls

1.1    Scope

Heating, Ventilation and Air conditioning (HVAC) Building controls are used to control the environmental conditions (i.e. temperature, ventilation rate and/or air quality) in individual zones (i.e. rooms or areas) within a building. They can be programmed to maintain these environmental conditions within pre-set limits in a manner that reflects occupation schedules, occupation status and/or level of activity in the zone, whilst also taking account of environmental conditions, and the specific operating requirements of the zone. These criteria are designed in order for controllers to be capable of functioning in an EN 15232 class A system.

A wide range of HVAC Building controls is available. The Energy Technology List (ETL) Scheme aims to encourage the purchase of products that automatically minimise the energy consumption of building heating, cooling, ventilation, or air conditioning equipment, and associated distribution systems.

Some products are also able to control lighting, electrical appliances and window shading equipment in a zone in line with its occupation schedule/status. For these applications, the respective criteria to be met are described in Table 1.8.

The Scheme covers three categories of products:

  1. ‘Add-on’ control modules that are not self-contained units but are designed to incorporate zone control facilities into HVAC control units or equipment.
  2. Control units not enabled to communicate with 3rd party devices
  3. Control units enabled to communicate with 3rd party devices

To be eligible for inclusion on the ETL, products shall meet the definitions and eligibility requirements as set out below.

1.2    Definitions

HVAC Building controls are products that are designed and programmed to automatically control in an energy efficient manner, the amount of heating, cooling, ventilation or air conditioning that is applied to individual rooms or defined areas within a building, known as “zones”.

“HVAC” is the collective term used to refer to the combination of heating, cooling, ventilation, or air conditioning that is specifically employed within a particular building. 

1.3    Requirements 

1.3.1    Eligibility requirements 

1.3.1.1    General  

To be eligible, products shall:

  1. Incorporate a microprocessor-based controller that is programmed (as factory produced, tailored to customer building or reprogrammed during an installation upgrade) to automatically control the individual environmental conditions in one or more zones within a building, in an energy efficient manner that reflects the occupation status or the level of activity in each zone. 
    Controllers operating under zone occupation schedules are authorised, under the provision that they are also capable of control under occupation status or activity level.   
  2. Be able to automatically control the operation of the equipment:
    a)    Heating and/or cooling the zones being controlled; and/or:
    b)    Ventilating and/or air quality the zones being controlled.
  3. Be designed to have at least two of the following zone operating modes:
    a)    A “normal/comfort” operating mode where zone environmental conditions are maintained within predefined levels consistent with zone occupation or a high level of activity in the zone.
    b)    An “economy/standby” mode where zone environmental conditions are maintained at reduced levels to reflect, for example, the fact that the zone is unoccupied, or a reduced level of activity in the zone or
    c)    A “off” mode where the zone heating, cooling, ventilation and air-conditioning is switched off or operated solely for fabric, frost and equipment protection.
  4. Incorporate an anti-tampering mechanism that prevents the product’s control strategy and configuration settings from being modified, and automatic control from being disabled, except during commissioning, maintenance or testing. 
  5. Conform with the requirements of The Electromagnetic Compatibility Regulations 2016, or have an appropriate Conformity Assessment mark.
  6. Make any feature allowing for building users to adjust temperature and/or ventilation settings in their zone to be only on a temporary basis. Products shall automatically reset user adjustments, either after a pre-defined time interval (which may be fixed or defined by the building manager) or at the next scheduled switching time. 
  7. Adhere to requirements detailed in Table 1.8 when controlling other types of equipment. If the product is not detailed in Table 1.8, then the control shall be based on status or levels of activity.
  • For control valves, actuators and dampers with integrated controls (i.e. factory assembled), these products shall be eligible under the HVAC Building Controls criteria.
  • For motors, pumps, fans and variable speed drives, controllers which are integrated (i.e. factory assembled) into these products shall also meet the relevant ETL criteria for the associated product. Where ETL criteria for the associated product does not exist, the integrated controller shall not be eligible for the ETL. This criterion does not apply for fans and pumps incorporated solely for the purpose of cooling the controller.  

1.3.1.2    Specific

  1. Comply with the relevant requirements for particular type of zone control and type of HVAC plant controlled, as set out in Table 1.1 to Table 1.7 below, for products that:
    a)    Control zone temperature (see Table 1.1).
    b)    Control zone ventilation rate or air condition (see Table 1.2).
    c)    Control based on zone occupation status or level of activity (see Table 1.3).
    d)    Control based on zone occupation schedules (see Table 1.4).
    e)    Control centralised HVAC plant (see Table 1.5).
    f)    Control wet heating systems (see Table 1.6).
    g)    Controls for workstation ventilation (see Table 1.7).

Table 1.1    Requirements for control zone temperature

Control of zone temperature

All products that are designed to control zone temperature shall:

  1. Be designed to directly measure zone temperature by means of a temperature sensor, and automatically adjust heat flow into, or out of, the zone to maintain temperature within the predefined temperature limits for the operating mode.
  2. Provide facilities that enable building managers to define the temperature set-points for each operating mode in each zone to +/- 1 degree centigrade.
  3. Conform with the requirements of BS EN 15500-1:2017, with control accuracy and control setpoint deviation are defined, such that they respect:
    a.    Control Accuracy for Heating is smaller than 2 degrees Celsius
    b.    Control Setpoint Deviation for heating is smaller than 2 degrees Celsius
    c.    Control accuracy for cooling is smaller than 2 degrees Celsius
    d.    Control setpoint deviation for cooling is smaller than 2 degrees Celsius
  4. Monitor internal temperatures and automatically switch zone heating circuits on or cooling circuits off, to stop condensation occurring and to protect building fabric.

    In addition, products that are designed to control both zone heating and cooling shall:
     
  5. Provide facilities that enable building managers to define separate temperature set- points for zone heating and zone cooling in each zone.
  6. Incorporate a mechanism(s) that prevent simultaneous zone heating and cooling, and frequent cycling of heating and cooling equipment on and off.

    In addition, products that are designed to control window shading equipment shall:
     
  7. If the product is capable of controlling window blinds or orientation of louvres, be designed to monitor the position of the sun, and automatically adjust the position of window blinds or orientation of louvres in a manner that minimises the entry of solar radiation, when the zone is in cooling mode, without excessive reduction in natural light. 
Notes
  1. Products that solely rely on an external, to the building, thermostatic device (for example, a digital thermostat) to determine when additional heating or cooling is required within a zone, are not eligible.

Table 1.2    Requirements for control zone ventilation rates or air quality

Control of zone ventilation rates or air quality
All products that are designed to control zone ventilation rate or air quality shall:
  1. Be designed to monitor zone ventilation rate or air quality by means of a presence detector, activity or air quality sensor (see Table 1.3, note 8), and automatically adjust the airflow into, or out of, the zone to maintain zone ventilation rates or air quality within the predefined limits for the operating mode.
  2. Incorporate a mechanism that automatically minimises ventilation rates in unoccupied zones, and in zones operating in economy or standby modes.
Notes
  1. Products that solely rely on an electronic or mechanical ‘timing out’ mechanism (for example, a spring-loaded button) to determine when a zone is unoccupied are not eligible.
  2. Products that have a “night cooling mode” that is designed to make use of natural ventilation to remove excess heat and cool the building fabric when the zone is unoccupied are eligible.

Table 1.3    Requirements for control based on zone occupation status or level of activity

Control based on zone occupation status or level of activity
All products that are designed to control zones based on occupation status shall:
  1. Be able to monitor zone occupation status by means of presence detector or activity sensor, and automatically adjust zone-operating mode to maintain environmental conditions within the predefined limits for the zone occupation status.
  2. Provide facilities that enable building managers or users to manually switch the zone into economy or standby mode, without disabling automatic zone controls.

    All products that are designed to control zones based on level of activity shall:
     
  3. Be able to monitor the level of activity in the zone by means of presence detector or activity or air quality sensor, and automatically modulate the amount of heating, cooling, ventilation and/or air-conditioning applied in a manner that reflects the level of activity in the zone.
  4. Provide facilities that enable building managers or users to manually switch the zone into economy or standby mode, without disabling automatic zone controls.
Notes
  1. The product may monitor zone occupation status by means of one or more presence detectors, or activity sensors, which may include for example, CO2 level monitors, heat or motion detectors, moisture sensors etc. However, manually operated devices (for example, electrical switches, electronic touch buttons or entry detection devices) are not considered to be presence detectors unless they automatically reset to a “no presence detected state” after a pre-set period of time.
  2. A key card activated master control switch may be used as an alternative to a presence detector, provided that:
    a.     when the key card is removed from it, it is designed to switch the zone controller into economy or standby mode and to switch off all lighting and electrical appliances being controlled.
    b.    the system returns to economy/standby mode if the card is left in the controller for more than 24h.
  3. Products that are designed to monitor the usage of lighting and electrical appliances by measuring energy use are eligible, provided that they are also designed to use a presence detector or activity sensor to detect that the zone is unoccupied, and then to automatically switch such equipment off.
  4. Products that are designed to monitor the operation of plant and machinery within a zone and raise an alarm when a fault or fire is detected, or when unauthorised occupation is detected, are eligible. In this context, a fault may include the local override of control settings or automatic control.
  5. Products that are designed to share the use of presence detectors and activity sensors with other types of management and control systems (e.g. building management systems) are eligible.

Table 1.4    Requirements for control based on zone occupation schedules

Control based on zone occupation schedules
All products that include a control zones based on occupation schedules shall:
  1. Automatically switch zones between operating modes, in accordance with the predefined and individual weekly occupation schedule for each zone controlled.
  2. Provide facilities that enable building managers to define the normal occupation times in each zone (in intervals of five minutes or less), for each day of the week, including  at least two periods of occupation per day (i.e. at least 14 different occupation periods a week).
  3. Provide facilities that enable building managers to define future dates (e.g. holidays) when zone heating, cooling, ventilation and air-conditioning should be in standby, economy, completely switched off, or operated at frost, fabric or equipment protection levels.

    In addition, products that also control zone heating and cooling shall:
  4. Incorporate a zone “optimum start” mechanism that monitors external and/or internal temperatures and calculates when heating or cooling needs to begin in the zone in order to reach the pre-set temperature by the start of the next occupancy period.
  5. Provide facilities that enable building managers to define different temperature set- points for each scheduled period of normal occupation throughout the day and week.
Notes
  1. Products that control domestic hot water (DHW) systems shall provide facilities that enable building managers to define a separate operating schedule for the operation of DHW systems.

 

Table 1.5    Requirements for control of centralised HVAC plant

Control of centralised HVAC plant
Where products control the operation of centralised HVAC plant, they shall:
  1. Incorporate a mechanism that enables the building’s HVAC systems to be easily switched into economy or standby mode, for example, when a scheduled activity finishes early.

    In addition, products that control central heating or cooling systems shall:
  2. Provide facilities to control the operation of the centralised heating or cooling systems, and zone environmental conditions based on zone sensor feedback  (as defined in Table 1.4).
  3. Monitor internal temperatures and automatically switch zone heating circuits on or cooling circuits off, to stop condensation occurring and to protect building fabric.
  4. Incorporate an overall “optimum start” mechanism that monitors external or internal temperatures, and calculates when the heating or cooling system needs to be switched on in order to reach pre-set temperatures by the start of the next occupancy period, after taking account of the requirements of each zone.
Notes
  1. Products that control centralised HVAC plant shall be designed to control at least two zones.

Table 1.6    Requirements for control of wet heating systems

Control of wet heating systems
Where products control the overall operation of wet heating systems, they shall:
  1. Incorporate a “weather compensation” mechanism that automatically saves energy during milder weather conditions, by reducing the temperature set-point of the boiler water circuit as the external temperature rises, and also the temperature of, or the heat flow through, the individual heating circuits for each zone controlled. 
  2. Incorporate a “frost protection” mechanism that monitors external and/or internal temperatures (or pipework temperatures), and switches on boilers and heating circuits as required to prevent equipment and pipework from “freezing up”.
  3. Provide facilities for building managers to “temporarily override” or manually adjust the degree (or amount) of weather compensation applied to each zone controlled.
  4. A mechanism that prevents the boilers supplying the heating system from “dry cycling” (i.e. switching on and off), when there is no change in heat demand.
  5. When managing multiple heat/chilled water generators, the controller shall be capable of managing generators according to a dynamic priority list based on load, efficiency and capacity of generators.
Notes
  1. The requirements in Table 1.5 also apply to products that control wet heating systems.

Table 1.7    Requirements for workstation ventilation controls

Controls of workstation ventilation
Where workstations are defined as delineated containable working surfaces, such as a kitchen or laboratory fume extractor. They shall:
  1. Adhere to the ventilation requirements detailed in Table 1.2
  2. Adhere to the control requirements detailed in Table 1.3
  3. Be designed to monitor the level of fumes and to automatically reduce the rate of extraction to the minimum necessary to maintain air quality within predefined limits.
Notes
  1. Specific to this technology group, a zone is defined as the extractors above a workstation.

Table 1.8    Additional requirements when other types of equipment are controlled

Type of equipment controlled Relevant ETL eligibility criteria
Electrical lighting equipment Lighting controls
Automatic monitoring and targeting equipment Automatic Monitoring & Targeting (aM&T) Sub-metering Systems
Commercial refrigeration equipment Refrigeration system controls
Two or more air compressors Master controllers

1.4    Verification for ETL Listing 

There are no testing requirements, however manufacturers shall provide sales and technical brochures to evidence the conformity of their products against the requirements from section 1.3. Manufacturers shall also provide evidence of conformity with the EN 15500 criteria, detailing control accuracy and control setpoint deviation values.

1.5    Conformity testing

Products listed on the ETL may be subject to the scheme’s conformity testing programme in order to ensure listed models continue to meet the ETL requirements.

1.6    Review 

1.6.1    Indicative review date 

The next technical review is scheduled for 2023-24. 

1.6.2    Illustrative future direction of the requirements  

Future changes to the specification may include:

a)    For controller units to be capable of remote internet access (potentially through a local central secured hub), allowing for remote operation and maintenance. 
b)    For controller units to be compatible to function with any 3rd party HVAC system, sensor or control device.

  • ETL scoping studies are underway on Building Energy Management Systems, Product systems and Smart products which may recommend future revisions to the HVAC Building Controls criteria.
  • ETL scoping studies are underway for pumps and fans. These studies may result in criteria for the inclusion onto the ETL.