Natural ventilation must be one of the most energy-efficient ways of cooling a building while providing reliable air flows.
Adding a natural light source or solar powered boost fan and save even more on electricity costs and reduce building carbon emissions.
Midtherm Engineering has been showing off its latest products, the X-Stream GRP roof terminal, a natural ventilation system for light commercial applications and its sister products, the X-Stream with Midtherm Solatube natural day lighting units, and the X-Stream with Solastar boost fan which has an integrated solar powered DC fan unit running through the centre.
The X-Stream airflow terminal is essentially a passive stack class 1 fire retardant GRP ventilation unit. The X-Stream ventilator has a specially-designed louvre blade, following three years of study by the company and Sheffield Hallam University. The X-Stream airflow louvre has been designed and proven to provide the most efficient air movement and gives 20 per cent less airflow resistance than all traditional 45º pitched louvre blade designs. It has been independently tested and validated by BSRIA.
The X-Stream ventilation terminal can also have a Solastar boost fan which helps to extract stale air from the internal environment, thereby forcing fresh air into the space below. The Solastar boost fan uses only the power generated by the solar panel; the sunnier it is the harder the fan works.
Performance figures
The guideline total airflow performance figures are: X-Stream stand-alone system 200 L/s; X-Stream with 250 mm Solatube 130L/s and X-Stream with 350mm Solatube 100 L/s. With the fan system the figures are 200 L/s plus the stated extract rate (BRE tests) of around 40L/s in overcast conditions to 152 L/s at full sun. A fully sealed modulating damper, grille and Siemens 24 v modulating actuator opens and closes the vents.
The X-Stream systems are controlled by a newly-developed MID2012 master control system which, says Andy Brown, director, will also offer control under different scenarios - for instance it can be used with natural ventilation, underfloor heating and cooling, open and close modulating window actuators and drive wall mounted natural ventilators - and the Master Control Panel will link to most building management systems utilising MODbus RTU integration.
Midtherm Engineering plans to sell the X-Stream roof units and MID2012 control solutions on- line later this year.
Dave Brown, technical development manager for the X-Stream, says it comes in three boxes, the customised roof plate in one, the damper, grille and actuator unit in another and the X-Stream Class 1 fire retardant GRP ventilator in the third box.
Technical helpline
The Solatube or Solastar fan units will come direct from the UK-based supplier. Full installation drawings and fixings packs are included. There is a technical helpline at Midtherm if an installer is in any doubt.
'All any purchaser needs to do is provide us with the angle of the roof and we can send a customised roof flashing plate to suit the application.'
However, Midtherm will send an engineer to measure the roof angle if it is required.
The X-Stream units can be used in new builds or retro-fitted to existing buildings.
The first installation is now complete, with eight terminals installed on the roof of the Kings School in Oxfordshire. The X-Stream units provide natural ventilation, cooling and add natural lighting to the corridors of The Kings School.
For the natural lighting Midtherm has collaborated with a Californian-based manufacturer which has been making natural lighting units for almost 20 years. Midtherm insists the Solatube is one of the most advanced natural lighting products available today.
The dome of the Solatube is injection-moulded from impact-resistant, UV stable acrylic and its geometry maximises light collection through the patented Raybender Fresnel lens and LITD light tracker technology.
The Spectralight Infinity reflective coating inside the Solatube optimises the light transfer as it makes its way down the tube.
According to Solatube UK the mirrored Spectralight Infinity tube material has a reflective value of 99.7 per cent.
Dave says that, when compared with other systems which use flexible ducting or lower grade rigid reflective tubing, a Solatube delivers on average 10 times more daylight, even with additional rigid angle extensions.