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Overcoming installation issues with “intelligent ventilation”

The challenge

Energy efficiency is rightly a key priority for us all – as businesses, individuals and society. Climate change is a political issue – with both a small and a capital ‘p’. Government contracts for instance now mandate a range of energy efficient aspects to the required specification. Great technology is now available to reduce the effects of climate change and help us lead healthier lives but installing it and using it correctly is all too often easier said than done.

A good example of this is the new Katherine Warrington secondary school in Harpenden where installation issues in the state of the art air flow design by Breathing Buildings gave rise to significant difficulties which needed to be overcome.

This case study about Katherine Warrington highlights the importance of skilled installation. Otherwise the new technology can be a pointless and expensive exercise causing immense frustration to both a building’s owner and the end users. This case study shows the power of finding an innovation solution once a project has gone off the rails to redeem it. This was achieved by using a specialist engineer.

The project

The Katherine Warrington School is a new build secondary school in Harpenden. Its award winning design makes use of state of the art air quality management systems to ensure a healthy classroom environment is maintained at all times with hot and cold temperature controls as well as CO2 levels.

This project was phase 2 of the new build which entailed supplying natural ventilation hardware to the mechanical and electrical contractor for their installation. The  commissioning would be done by Breathing Buildings to ensure that everything worked according to specification

The system installed

The mechanical and electrical contractor had unfortunately incorrectly instructed its staff about the correct specification of the Breathing Buildings’ natural ventilation system. This meant that the contractor had wrongly programmed the software. The software therefore had to be significantly re-programmed before  the commissioning could successfully take place.

There were a number of rooms in the school with Breathing Building’s natural ventilation systems installed. The main area of concern was the Dining Hall which had a passive ventilation system. This passive system employs a series of low level windows (electrically controlled for opening and closing) that work in conjunction with a number of roof windows (electrically controlled for opening and closing). The Dining Hall has two (one at each end of the Hall) combined room temperature and CO2 sensors that provide live readings back to a Breathing Buildings’ control processor.

The planned installation was intended so that the Breathing Buildings’ control processor would record the room temperature and CO2 data being sent from the two room sensors. Create average temperature and CO2 readings and use them to calculate the appropriate amount of opening for each level of windows. However before sending commands out to the windows to open or close, the control system must assess the outside weather conditions to limit the opening if necessary to provide weather safe opening, ensure comfortable use of the Hall and mitigate rain water entering the building.

The outside weather information was planned to be processed by the building’s main computer control system ( the ‘Building Management System’ – BMS). The BMS uses its weather station information for many purposes but should also pass this information in a scaled value to the Breathing Buildings control processor. The BMS weather scaled value would provide a simple zero to 10 value of live weather reporting to which the Breathing Buildings’ natural ventilation system within which it could accordingly operate. This would allow for safe and calculated opening of the low level and roof level windows in variation and influenced by interior air quality and outside weather conditions combined.

The problem

Unfortunately the mechanical and electrical contractor had not instructed the BMS weather station information to be processed by its engineers into a simple scale. Instead the data was sent as raw wind speed, wind direction and rain data direct to the Breathing Buildings’ processor.

To correct this fault in the installation, the Breathing Buildings machine processor software had to be modified significantly to incorporate also the weather station processing. Initially the specialist engineer brought in set filters to the raw data to create a scale for each condition and then tried the simple route of some additional computer logic (e.g. If, AND, OR etc…) but this proved too large for the machine’s processor memory capacity. To keep the size of the programme within the memory capacity of the machine processor it was necessary to construct a new way of scaling this information and in effect change the method in which the programme was designed to respond.

The final result was we created a single integer value that is unique for any combination of weather conditions, we called this a “Decimal Value Accumulator”. For example:

Raining =1 / equivalent binary value 00000001
Not raining =2 / equivalent binary value 00000010
Wind direction 45 degrees from North =4 / equivalent binary value 00000100
Wind direction 60 degrees from North =8 / equivalent binary value 00001000
Wind speed of 2 metres per second =16 / equivalent binary value 00010000
Wind speed of 4 metres per second =32 / equivalent binary value 00100000

If we had a weather condition of:

Not raining =2 / equivalent binary value 00000010
Wind direction 45 degrees from North =4 / equivalent binary value 00000100
Wind speed of 2 metres per second =16 / equivalent binary value 00010000
The accumulated value would be =22 / equivalent binary value 00001101

By changing any of the above weather conditions we would calculate a new value that will always be unique to that combination of weather only. So once we set out a unique weather identifying process we needed to reduce the weather combinations by filtering out the extreme areas of weather(i.e. weather beyond safe operation)and then scale up the example process to fit our weather scale.

The outcome

The Decimal Value Accumulator process created by the specialist engineer mentioned in the above paragraph made for a very neat and efficient way of providing weather based control. Ultimately the changes to the programming allowed unusual on board machine processing of the raw weather station data to allow a ‘Plug and Play’ weather to influence the opening and closing of the high and low level windows. This achieved a bespoke control system and helped Breathing Buildings to support the mechanical and electrical contractor towards completing their work on time and to the satisfaction of the school.

Testimonial

“Ian joined Breathing Buildings on a temporary contract to support our engineering team through an intense period of projects with complex controls requirements. He also helped to transfer knowledge to our newly appointed Controls Engineers.

Initially Ian’s focus area was in the development of some project specific software programming to give users greater control over the building (eg airflow). His work soon expanded out into broader project management and engineering responsibilities. His comprehensive understanding of our natural and hybrid ventilation business was excellent and he became adept at providing and implementing project tasks for customers. He often went above and beyond to ensure the optimum solution within the timescales required.

Ian built a great relationship and rapport with our whole team and also with many of our customers along the way. Ian became integral to the whole team in achieving our business objectives and greatly extending his involvement with us and value to us.”

Steve Newcomb, I.Eng. M.I.E.T
Operations Director, Breathing Buildings Ltd