Efficient climate control system reduces energy consumption in buildings


The Sally R Air handling Unit

Technology abstract

Sally R is a Swedish cleantech company that offers an efficient air handling unit for indoor installation. The technology is based on optimization algorithms which control ventilation and air contamination. The main advantages are a lower energy consumption in buildings and better indoor air quality. 

- Private group -

- Cecilia Hertz -

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Technology Description

Air quality control in spacecraft has been a concern since space travel began. The system used today at the International Space Station (ISS) was originally developed during the 60’s and 70’s by several parties, including both ESA and NASA. ESA has published articles on the subject, which has been used in the development of the air handling unit by the Technology Provider.

The problem that ESA, NASA and their partners have solved regarding air quality control in spacecraft at the ISS, is how to revitalize air in an enclosed environment. They have proven that it is possible to build a system for enclosed environments that is stable over time and removes a broad spectrum of trace contaminants.
The system for air quality control is called Closed Loop Air Revitalization System (ARS). An air revitalization system includes temperature, humidity, oxygen, nitrogen, carbon dioxide and trace contaminant control.

Since the ISS is in space, the air revitalization system controls air quality in the spacecraft without ventilation with ambient air. Therefore, if the system is brought down to earth and applied to a residential building, the indoor climate could, in theory, be made independent from the ambient air. However, if the trace contaminant control system is combined with an HVAC system, climate control can be expressed as a nonlinear optimization problem. In the optimization problem the energy consumption is to be minimized. The parameters to be optimized are e.g. the ambient ventilation, carbon dioxide removal and removal of other trace contaminants. The technology the company is developing is here defined as Air Handling Optimization (AHO).
The solution to the optimization problem is applied in a control strategy where ventilation and the trace contaminant control system are used in such a way that the air quality is kept at a desired, and user specified level, to the lowest energy consumption possible. 
For example, if the ambient air is heavily polluted, hot and humid (e.g. Paris, London or Hong Kong at rush hour), and the internal air pollution is low (few people in the building, due to the traffic...), the ventilation is reduced and the indoor air quality is controlled using mainly the AHO unit since this is the most energy efficient solution at this time. On the other hand, if the ambient air is clean and in the comfort zone, and the indoor air pollution is high (many people in the building), the most energy efficient solution is to lead ambient air into the building. Furthermore, there can also be many combinations thereof. Here, it should be noted that the indoor air quality, using this setup, can be better than ambient air quality which is not the case for other demand control ventilation solutions.

Innovations & Advantages

State of the art competing technologies are heat exchangers, air filtration, air purifiers and demand controlled ventilation.
Air Handling Optimization (AHO)

This is the only technology than can simultaneously reduce energy need and increase indoor air quality. Moreover, the indoor air quality can be user specified.
Heat recovery (FTX)

The ongoing trend on the HVAC market is ‘Exhaust and Supply Air Ventilation with Heat Recovery’ (known as FTX systems on the Swedish market).
Increased air filtration (IAF)

Air filtration systems were developed to protect the HVAC system’s coils, ductwork, and other components from dust and dirt. They have since evolved to the point where they today serve as the front-line defence in maintaining a building’s indoor air quality. However, a filter installed in an HVAC system offers resistance to the air the system supplies to the conditioned space. Moreover, an air filter does not remove gases such as CO, CO2, NOx. 
Stand-alone air purification (SAAP)

Stand alone units for indoor air quality improvement. Since these products are fairly easy to ship, they target a global market. The major players are Alen air, RabbitAir and Blueair (recently acquired by Unilever).
Decreased ventilation (DV)

Technique where isolation is improved and ventilation decreased. The goal of this technique is to decrease the buildings energy usage but has often come at the price of reduced indoor air quality and sick buildings.
Demand controlled ventilation (DCV)
DCV offers automatic adjustment of the ventilation depending on current occupation of the area. Since DCV is controlled on room/zone level it requires more technical equipment since two active valves needs to be installed for every room and thus a larger initial investment than a regular HVAC solutions. 

Further Information

Technical specification
Nominal power 6kW

Airflow 3000-8000 m3/h
Length: 2.1-4.9m
Height: 1.6m
Width: 1.5m
Weight: 450-750kg

Nonlinear optimization algorithms
Automatic flow control supply air
Automatic flow control exhaust air
Automatic flow control return air
Automatic regeneration adsorption filter
Speed control on rotary heat exchanger
Touch display
F9 filter

F5 filter
Adsorption Filter
Heating and cooling

CO2, VOC, PM0.3 PM2.5, PM10, RH och T.
Optional sensor
NO2, CO, SO2, O3, Formaldehyde

Current and Potential Domains of Application

Indoor climate control.
Suitable for all kinds of buildings: schools, hospitals etc.