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Article Date: 12th February 2016

Monodraught & Brunel University Publish REHVA Journal Article “Ventilative Cooling of a Seminar Room Using Active PCM Thermal Storage”

REHVA Journal - Ventilative Cooling - Ventilation System - Cool-Phase

Monodraught Cool-Phase

Monodraught has a long history of innovating and pioneering the launch of sustainable, low energy products for the built environment. We have partnered with many leading UK universities to research cutting edge technologies and also have an active research and development team based at our head office in High Wycombe.

Cool-phase® is a low-energy cooling and ventilation system that creates a thermally comfortable, fresh and healthy indoor environment whilst reducing the energy consumption and running costs of buildings.

Together with the Institute of Energy Futures at Brunel University London we have undertaken a year-long monitoring programme of our Cool-phase ventilation and PCM battery system in a seminar room at another university, in order to measure thermal comfort, indoor air quality and energy usage.

Whilst Cool-phase systems have been installed in other spaces of the university, the seminar room was chosen because of its use as a computer laboratory with higher internal heat gains than other spaces. The room has a floor area of 117 m² and includes 26 desktop computers and a peak occupancy of 26 students. Artificial light comprises 24 luminaires, each equipped with one 48W lamp. Ventilation and cooling is provided via an 8kW Cool-phase unit. Heating is provided through perimeter hot water radiators and windows are operable.

The journal article shows data taken over the course of 2013, in particular the summer months (May-September) and shows that the Cool-phase system maintains the room temperature within the upper and lower limits of the Education Funding Agency criteria, i.e. the temperature of the room remains between 20°C-28°C.

An analysis of monitored room CO2 concentration was also carried out for the whole year where data is available. Daily average concentration during the occupied period was always less than 1,000 ppm and the 1,500 ppm limit was not exceeded. The guidance within the March 2014 EFA “Environmental Services Strategy” and “Ventilation Strategy” states that ventilation should limit the concentration of carbon monoxide measured at seated head height in all teaching and learning spaces. Daily average concentration of carbon dioxide during the occupied period should be less than 1,000 ppm and the maximum concentration should not exceed 1,500 ppm for more than 20 consecutive minutes each day.

The fan energy used by the system for the year was calculated to be 90kWh. This equates to 0.77kWh/m²/annum. Annual electricity energy use intensity for secondary schools has a median of 56kWh/m² when moving from “heating and natural ventilation” to “heating and mechanical ventilation” buildings. CIBSE TM57 presents good case studies on natural ventilation systems with cooling energy intensity of 3.5kWh/m² showing the Monodraught system to be extremely energy efficient.

Further analysis of a second year of operational data, plus additional monitoring to study the distribution of environmental conditions in the room and feedback by users, is now under progress and will be reported in an additional case study.

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