The following equipment is covered under the HVA category of the ETL:
- HVAC Building Controls
- Active Chilled Beams
- Close Control Air Conditioning
- Evaporative Coolers
HVAC Building Controls
HVAC building controls are specifically designed 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 within a building, known as “zones”. In general, these controls are applied to five types of HVAC equipment:
- Wet (hydronic) heating systems.
- Underfloor or storage heating – wet systems and electric heating.
- Air conditioning and comfort cooling.
- Chilled water systems
Effectively managing the use of energy within a building through the implementation of zone controls, that have been properly installed and commissioned, can result in up to 20% savings over systems without this level of control.
Building Controls for Heating/Cooling Systems
ETL compliant heating/cooling controls can be used for both wet (hydronic) and electric heating systems as well as chilled water systems.
Systems are controlled by a temperature sensor and predefined temperature set-points. Further refinement to the controls can be given by activity and occupancy sensing or schedules.
Temperature can also be controlled by automating window shading. These products use solar tracking sensors, to adjust internal or external window shades to minimise the need for cooling.
Example: for the installation of electric underfloor heating zone controls where none previously existed within a typical 1,000m2 naturally ventilated cellular office building, using 151kWh/m2/year on heating, the potential annual savings at 20% are calculated as:
- 30.2 MWh of space heating
- 10.6 tonnes of CO2
Other benefits of underfloor heating systems include the ability to provide more consistent and even heating across a space compared to traditional radiators. They can also provide heat to a larger area than an individual radiator and could reduce heating bills.
With improvements in building fabric insulation and levels of air-tightness (reduced air infiltration), the relative contribution that ventilation makes to a building’s energy consumption is increasing.
The ventilation to a zone can be controlled by activity, occupancy or air condition sensors. This ensures appropriate airflow to a zone, as well as appropriate air quality. Unoccupied zones can be switched to an economy or standby mode.
Some products have a “night cooling mode” to remove excess heat by natural ventilation when the intended zone is unoccupied.
The same system controls for heating, cooling and ventilation can also be used to control lighting and electrical appliances to create a fully integrated system.
Example: for installation of ventilation zone controls where none previously existed within a typical 5,000m2 air-conditioned office building, using 109kWh/m2/kWh of gas for space heating and cooling, the potential annual savings at 20% are calculated as:
- 287 MWh of space heating/cooling
- 71.1 tonnes CO2
- 1.7 years payback
ETL listed warm air and radiant heating systems are also available.
Comfort Cooling and Air Conditioning
There are a wide range of air conditioning and comfort cooling systems, including constant air volume systems, variable air volume systems (VAV), fan coils and heat pumps. As with hydronic heating systems, zone controls can play an important role in ensuring that air conditioning and comfort cooling systems maintain desired internal conditions without wasting energy.
Example: for the installation of cooling system zone controls where none previously existed within a typical 1,000m2 air-conditioned office building, using 109kWh/m2/year electricity for space cooling, the potential annual savings at 20% are calculated as:
- 21.8 MWh of space cooling
- 7.7 tonnes CO2
- 1.8 year payback
ETL listed air to air energy recovery systems are also available.
Active Chilled Beams
Active chilled beams are specifically designed to deliver chilled air into an environment in order to achieve comfortable working and living conditions.
Active chilled beams can be an attractive alternative to fan coil units, which are typically more energy intensive and costly to run. Active chilled beams can therefore offer an energy cost saving of 20-25%. Active chilled beams also have a longer lifetime than conventional space cooling systems.
Example: the potential annual savings of installing ETL compliant active chilled beams over traditional fan coil units, in a typical 1,000m2 air-conditioned office building, using 109kWh/m2/year electricity for space cooling, are calculated as:
- 23.5 MWh
- 8.3 tonnes CO2
Close Control Air Conditioning
Close control air conditioning equipment is designed to control the temperature in rooms containing equipment or processes that generate heat. It also offers the option to control relative humidity. They are typically used in rooms containing servers or other computer, electronic and telecoms related equipment; or where temperature sensitive industrial or laboratory processes are carried out.
Close control air conditioning is estimated to account for around 40% of all UK packaged air conditioning energy consumption and around 20% of the entire air conditioning sector.
Direct Expansion (DX)
Direct expansion close control air conditioning units use the expansion of a refrigerant vapour to provide cooling. The warm air to be cooled is simply passed directly over the refrigerant fins, before being returned to the space to be cooled.
This system has advantages in that the entire unit is self-contained. This allows for easier and less costly installation as well as being able to be installed on a smaller footprint compared to other forms of air conditioning.
There are four types of direct expansion close control air conditioning equipment eligible for the ETL:
- Air cooled without free cooling coil
- Air cooled with integral chilled water free cooling coils
- Water cooled without free cooling coil
- Water cooled with integral chilled water free cooling coils
Example: for the installation of an ETL listed 60kW DX air cooled close control air conditioning unit, the potential annual savings are calculated as:
- 82.5 MWh
- 29 tonnes CO2
Chilled Water (CHW)
Chilled water close control air conditioning equipment can be an efficient and popular option for large installations, and spaces with a high cooling demand.
CHW systems rely on a chiller unit which reduces the temperature of the water before it is piped around to where it is needed within a building. This system works well in comparison to traditional air conditioning thanks to the non-corrosive, non-toxic nature of water.
Example: for the installation of an ETL listed 80kW chilled water close control air conditioning unit, the potential annual savings are calculated as:
- 39 MWh
- 13.7 tonnes CO2
Dual mode close control air conditioning is able to take advantage of both a DX and CHW system. This means that it is able to operate in the most efficient mode depending on the cooling demand required.
These systems can be useful for cooling in highly controlled environments where backup is required in case of one cooling system failing, or to manage spikes in cooling demand. The potential for continuous, no-downtime operation over many years makes these systems ideal for use in the IT sector and for hospitals.
There are two types of dual mode close control air conditioning equipment listed on the ETL, these include:
- Air cooled and chilled water cooled
- Water cooled and chilled water cooled
Evaporative Air Coolers
An evaporative air coolers is a device that cools air through the evaporation of water. Evaporative cooling is used for commercial and industrial cooling as an alternative to refrigeration based cooling and is increasingly popular in data centres. Substantial energy savings are achieved because there is less power requirement involved in evaporative cooling systems compared to refrigeration-based ones.
This form of cooling offers other advantages over traditional air conditioning thanks to the fact it doesn’t rely on any harsh chemical coolants, needs no heat rejection duct, consumes relatively little power, operates more quietly, and does not lead to the dry, refrigerated air often associated with air conditioning. However, it does require a constant source of water to operate.
There are two types of evaporative air coolers eligible for ETL:
- Direct – primary air supply is cooled by evaporation. This can lead to high humidity levels in the cooled air produced. Direct evaporative coolers can achieve energy and carbon savings of up to 80% compared to air conditioning.
- Indirect – a secondary air supply is cooled via a heat exchanger from the initially cooled primary air supply. Indirect evaporative coolers can achieve energy and carbon savings in data centre applications of around 75% compared to a chilled water cooling system with 100% recirculation and around 50% compared to a direct free cooling system.