Introducing Cool-phase, Monodraught’s low energy ventilation and cooling system

Monodraught has announced the next generation of its award-winning Cool-phase system, representing the company’s latest innovative application of phase change material (PCM) as a thermal energy store to actively ventilate and cool buildings.

Cool-phase is a low energy cooling, ventilation and heat recovery system that reduces the running costs of buildings while creating a fresh and healthy indoor environment without compressors or hazardous coolants. The system uses intelligently controlled phase change material (PCM) to actively ventilate and cool buildings, maintaining temperatures within the comfort zone, while radically reducing energy consumption by up to 90% compared to conventional cooling systems.

The improvements provided by the new generation follows an intensive and all-encompassing two-year development programme during which the Monodraught R&D team has applied innovative new design practises and some of the most advanced manufacturing technologies available to create ground-breaking improvements.

As well as dramatically reducing design and development time the programme has provided significant enhancements and improvements in almost every aspect of the Cool-phase system.

Commenting for Monodraught, technical director Nick Hopper says:

“Cool-phase has exceeded our expectations in terms of design, performance and energy efficiency and we are delighted that the second generation of system offers the building services industry such a dramatic improvement to any alternative ventilation and cooling strategy.”

Natural ventilation, daylighting and cooling specialist Monodraught has created a comprehensive new website to introduce Cool-phase.

Ten individual website sections use a combination of high impact design and detailed description to present Benefits, How Cool-phase Works, Applications, Systems, Building Simulation, Controls, Case Studies, Specifications and Performance, and Installation and Maintenance. Also covered are key customer benefits such as the more stylish, lightweight and stronger housing; much improved acoustic and thermal performance; almost unbelievable fan performance that dramatically reduces energy consumption during typical daytime operation to between 7 and 20 Watts; typical running costs of approximately £20 per year; and why Cool-phase is also significantly quieter in operation!

In addition, Exposed Void, Suspended Ceiling and Facia models are explained – the minimum ceiling void for suspended ceiling installations is now just 400mm; and Cool-phase is faster and easier to install using the highly-efficient ‘Gripple’ system.

Monodraught Business Manager, John Curley says the website graphically demonstrates how Cool-phase has exceeded expectations in design, performance and energy efficiency; and how the second generation offers the building services industry such a dramatic improvement to any alternative ventilation and cooling strategy.

Cool-phase Delivers Low Energy Ventilation and Cooling for Anglia Ruskin University Computer Room

  • Location: Cambridge
  • Contact: Andy Lefley, Assistant Director Building Services
  • Systems: Cool-phase® system
  • Sector: Education

Bryant Building Computer Room

In January 2013 a computer room used by the Faculty of Science and Technology at Anglia Ruskin University in Cambridge had its aging air conditioning system replaced with two Cool-phase low energy cooling and ventilation systems. The units were fitted discreetly within the existing ceiling void.

Andy Lefley, Assistant Director of Building Services, Estates & Facilities said:

“I am very excited by this technology and the opportunity to improve student comfort without increasing the energy burden to Anglia Ruskin.”


In an effort to reduce their energy consumption, Anglia Ruskin University were keen to explore low energy alternatives to conventional air conditioning technologies. Two Monodraught Cool-phase systems were specified to serve the Science & Technology classroom, replacing the existing end of life air conditioning system that provided comfort cooling but no ventilation. The Cool-phase system provides intelligently controlled ventilation and naturally cools the area through the use of phase change material housed in thermal battery modules. The systems maintain thermally comfortable conditions and good air quality levels throughout the year.


Monodraught’s design engineers carried out dynamic thermal modelling, the results of which determined that 2N° 8 KWhr Cool‑phase systems were required to ventilate and cool the space.

As is often the case with retrofit projects, the installation was rather challenging. At the Anglia Ruskin site the conventional wall louvre assembly for supply and exhaust air had to be reconfigured due to the existing building construction. The design team engineered a solution that utilised a roof mounted supply and exhaust system to serve the two Cool-phase units.

The installation was carried out by Monodraught’s installation team in January 2013 to prevent disruption to teaching commitments.

Clients’ Comments

“I am grateful to the department for allowing us to trial this equipment in Bryant. We will be monitoring it closely to see if it has the impact we hope it will. If the trial is successful, the Estates & Facilities team will consider a range of further applications across the Cambridge and Peterborough campuses.”


Each Cool-phase system continually monitors and records temperature, CO2 concentration and energy usage. The results displayed below are based on data collected by the units installed in Room 016 from 25th January 2013 to 2nd September 2013.

Internal Temperature

Table 1 shows the average daily temperatures for the Science & Technology computer room. The readings clearly demonstrate that the Cool-phase systems have consistently maintained the internal temperature within a comfortable band.

Table 2 shows the percentage of time that the internal temperature has exceeded 25°C, 28°C and 32°C during the data logging period.

The Cool-phase systems have maintained an ideal temperature within the room of less than 25°C for 97% of the occupied hours across the thirty one week period. At no point has the room exceeded either 28°C or 32°C. This level of performance far exceeds the target overheatingcriteria stipulated by both CIBSE Guide A and BB101.

CO2 Levels

The typical background or atmospheric CO2 concentration is recognized as approximately 400 parts per million (ppm). In education facilities CO2 levels should ideally remain below 1500 ppm, with levels above 1500 ppm considered high.

Table 3 shows that the CO2 concentration in Room 016 where the two Cool-phase units are installed is consistently maintained below the threshold level.

Energy Consumption

Table 4 shows the energy consumption of the two Cool-phase units installed in the Bryant building. The combined usage was 197.6 KWh of electricity across the thirty one week data logging period. Assuming a standard electricity tariff of 0.11£/KWh, that amounts to total energy costs of £21.74, or just 70 p a week for the two Cool‑phase units.


Monodraught has demonstrated that the Cool-phase systems meet the design criteria and specification that the client requested, that being the requirement for comfort cooling to maintain internal temperatures within an acceptable temperature band and for the provision of fresh air such that CO2 levels remain within acceptable boundaries. The results displayed in this case study show that the solution has complied with the overheating and air quality criteria, keeping temperatures and CO2 concentrations within acceptable levels. This has been achieved with very low energy usage and equally low running and maintenance costs.

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