Friday, 20 January 2017

CIBSE Year in Pictures

It's a new year and a new start, but let's not forget all that came before in 2016! PR and Communications Executive Matt Snowden presents a picture gallery of some of 2016's best moments from head office, the regions, the groups and societies and beyond!

It's been quite a year here at CIBSE, with enough launches, awards, events and milestones to fill a decade. CIBSE has a dedicated network of members, volunteers and staff all around the globe who are striving to spread the art and science of building services engineering, and to make the industry and the planet a better place as a whole. Below is a slideshow of snaps to show just some of the things you got up to over the last 12 months.


(Note: The slideshow is best viewed in full screen mode. To access full screen mode, click the arrows in the bottom right-hand corner. To view captions, click 'show info' in the top right-hand corner)

Friday, 13 January 2017

Northern lights

The 2016 awards season has come and gone, and the year's achievements have been well and truly celebrated. But this year saw the launch of a ceremony with a difference. Simon Owen, Director at Calibre Search and Chair of the CIBSE Yorkshire Region, looks back at the first services awards outside London.

On the 18th November I nervously welcomed over 300 guests to the Royal Armouries in Leeds. A marked departure from their traditional annual dinner, the Yorkshire Region Awards 2016 (CYAs) were a first for a CIBSE region, the organising committee and the only services specific awards outside London. I need not have been too concerned, because behind me were a small army from a range of sponsors and entrants plus industry recognised speakers and a small group of volunteers who ensured the events success.

The CIBSE Yorkshire Awards are not mine, theirs or CIBSE’s: we wanted to create an opportunity for the Yorkshire Building Services family to gain recognition for their achievements to enable professional and commercial benefit for themselves and the whole industry; we have merely facilitated, and that opportunity was certainly taken.
The CIBSE Yorkshire Awards are about more than just the trophies
Certainly, trophies were given: to those with the highest CPD hours as well as the more traditional “X of the Year” awards for Project, Small and Large Consultancy in addition to categories for Students, Manufacturers and Facilities Management teams. But it wasn’t just an evening for back-slapping and handing out prizes – we also wanted those who attended to come away with some genuinely new and inspiring ideas that they could then share throughout their businesses and networks in Yorkshire and beyond.

Addressing the audience, Chris Gorse from Leeds Sustainability Institute discussed climate change and the role of building services engineers in educating clients and creating solutions. As well as quoting Spiderman (“with great power, comes even great responsibility”), he issued this call to action:

“As services engineers, the most powerful Environmental Engineers in construction, we have to innovate to help sustain the things we have grown to love.”

Chris Gorse from Leeds Sustainability Institute
There were a lot of exciting, innovative and interesting projects on show. While Adam Smith from The Real Junk Food Project, (TRJFP) had to withdraw from speaking, their work is deep, green thinking. By intercepting food surplus and distributing it on a Pay as You Feel basis, TRJFP has created training opportunities, enhanced feelings of self worth and reconnected people with their senses around food and social value. Using the example that of a 40% waste allowance when externally insulating a house, there must be scope for a similar scheme in construction.

This, and other projects exhibited on the night, are a perfect example of what the Awards were about. We’re not here to pontificate, and tell the industry what they should be doing in building. We’re here to show by example what is possible, and demonstrate the enormous benefits that innovating along similar lines can bring. To inspire, rather than insist.

In a similar vein, we were joined by three great speakers who certainly inspired. The first was Peter Hansford, former Chief Construction Adviser, who gave a brief overview of the industry; the innovation, the world class expertise and the ability of UK companies to compete on the world wide stage. Peter also discussed the looming skills shortage affecting not just construction, but all industries, and so the need for construction to compete for the talent it needs to ensure its future success.

This led on to Helen Vardy of King Ecgbert School in Sheffield, whose pupils won the Class of Your Own (COYO) design competition to design a school for the Parabongo region of Uganda. She told the audience what COYO brought to her students and how it gave them an insight in to all aspects of building engineering as well as the chance to use the same tools that the industry does, in the same way.

To prove this Alison Watson from COYO launched her #BuildParabongo crowd funding campaign to take the King Ecgbert team’s design, which has since had detail design input from Arup and BAM providing costing information, and turn it in to a real, live school for the community.
The University of Bradford team with their award
In another departure from tradition, as well as raising funds at the Awards, guests also donated time and skills to The Real Junk Food Project and COYO by making pledges. This was inspired by Adam Smith’s Pay as You Feel model which demonstrates that everyone has something to offer beyond currency.

Peter Hansford summed up the night itself and its goal of creating a forward thinking legacy:

"The CIBSE Yorkshire Awards was a great success.  My congratulations to all the award winners.  I hope that many of your members take up the call to help inspire the next generation into construction, by supporting Class of Your Own and its #BuildParabongo appeal."

Given the format of the evening, the financial donations coupled with the pledges made to give time and skills to the Real Junk Food Project and COYO as well as the Awards themselves, there is a good chance that hope will be fulfilled. We're already getting the 2017 edition in the calendar, so if this sounds like something you'd like to be part of - visit the website.

Friday, 6 January 2017

A chill in the air

With a United Nations agreement promising to slash the use of hydrofluorocarbons (HFCs) in refrigeration and air conditioning systems by 85% by the 2040s, we have been covering the race to find a suitable replacement. This week, Simon Lamberton-Pine, Managing Director of DPAC UK, makes the case for a different kind of chiller...


'Absorption is the process in which a fluid is dissolved by a liquid or a solid (absorbent). Adsorption is the process in which atoms, ions or molecules from a substance (it could be gas, liquid or dissolved solid) adhere to a surface of the adsorbent. Adsorption is a surface-based process where a film of adsorbate is created on the surface while absorption involves the entire volume of the absorbing substance.' "Absorption vs Adsorption." Diffen.com. Diffen LLC, n.d. Web. 29 Dec 2016

Ok, so now the technical explanation is done, lets move on to why you should be considering the use of ADSORPTION, which is the main reason for writing this feature! But before that perhaps it would be better to look at the features, potential uses, and applications of the technology.

Adsorption causes molecules to adhere to a surface rather than add to
its mass, as in absorption
As a result of the recent HFC Phase out programme, there is heightened interest in environmentally friendly and sustainable alternatives to traditional chillers for cooling use in commercial and industrial applications. Most of these are already well known (absorption, CO2, propane, ammonia – among others) however probably the least well known is adsorption.

Adsorption equipment is only currently available from a handful of manufacturers, and therefore their individual product designs vary, however their principle of operation is the same. Adsorption chillers are ideal when used 24/7,  operate at high efficiency – even with variable loads, and also produce chilled water rapidly from start-up.

Chillers, which often have 25yr lives, will
be most affected by the new rules
An Adsorption chiller is a highly reliable, virtually zero maintenance, efficient solution that uses waste heat i.e. from CHP or Solar to produce chilled water, which can then be used for air conditioning cooling or connected for refrigeration applications. Adsorption technology produces chilled water down to as low as 3ยบ C which is ideal for any application with a high cooling demand such as Commercial offices, Process cooling, Supermarkets, and Data centres.

The chillers can be used in applications where there is a waste heat source, i.e heat recovery off a process, Biomass Boilers, Solar Panels, District Heating or via a CHP process. These highly efficient chillers provide great cooling capabilities and uses water as its cooling agent, so it’s highly environmentally friendly.


With water as the refrigerant, any piping or valve installation can be undertaken easily as there are no hazardous substances such as lithium bromide or ammonia. The chillers have long life expectancies of 20-30 years and end of life disposal is easy as the chillers have no hazardous refrigerants to dispose of.

For more information on the above, watch these videos by SorTech AG on the Technology and Applications of adsorption chillers.

Adsorption chillers can cool buildings using their own waste heat, which
is idea for use in data centres
Primary advantages
  • Adsorption chillers can deliver a substantial reduction in both primary energy consumption and carbon emissions.
  • Adsorption chillers can operate efficiently with a lower heat source thereby delivering cooling solutions to a wide range of applications.
  • Maintenance is kept to a minimum because the Adsorption chillers use such a simple process; the downtime is minimal with no potential crystallization issues associated with Absorption
  • Long life cycle 20- 30 years of operation.
  • Adsorption chillers can be utilized with dry coolers available in micro channel design from DPAC
  • The are no hazardous substances within the chiller (i.e. HFC’s, lithium bromide or ammonia); it uses silica gel (a natural substance) and water as a refrigerant. Therefore, the whole process is highly environmentally friendly - right through to end of life disposal
  • Additionally, our Sortech models are available in a variety of smaller capacities from just 10Kw, which can easily be connected. By coupling individual modules, projects can be applied up to a nominal capacity of 310 kW
  • The cooling water evaporates in a vacuum and thereby extracts heat from its surroundings (evaporating-energy). Through this process, cooling takes place. There are no high voltage motors or large compressors and no special external temperature controls are required for capacity control or to protect the chiller
Adsorption chillers keep maintenance costs down by reducing the amount
of equipment required
UK based M&E Consultants, Contractors and FM Businesses should now be considering adsorption equipment as an alternative (particularly if they know of a project with waste heat availability) and in most cases, they are far more cost effective, being more efficient and with substantially lower running costs. Obviously, there are pros and cons to all types of cooling equipment and in particular to adsorption equipment, but one of the biggest pros is that adsorption equipment is available through the Government backed grant scheme, however there are some criteria that must be met before being considered. 

The Renewable Heat Incentive (RHI) is a UK Government scheme set up to encourage uptake of renewable heat technologies amongst householders, communities, and businesses through financial incentives. It is the first of its kind in the world and the UK Government expects the RHI to contribute towards the 2020 ambition of 12% of heating coming from renewable sources. The Renewable Heat Incentive has two schemes - Domestic and Non-Domestic. They have separate tariffs, joining conditions, rules, and application processes. 

The Non-Domestic Renewable Heat Incentive (RHI) is open to industrial, commercial, public sector and non-profit organisations with eligible installations in Great Britain. This includes small Businesses, Hospitals, Schools as well as district heating schemes where one installation serves multiple homes. To qualify for the non-domestic or commercial RHI grant the installation must supply renewable heat to an eligible load and be supplied by an eligible source.

Adsorption chillers work with renewable heat sources, such as
 water source heat pumps, so are eligible for grants
The RHI will support heat where that heat is used in a building for ‘eligible purposes’, for example, heating a space, heating water or for carrying out a process where the heat is used and the heat must be transmitted by water or steam. For a building to qualify for space heating it must be totally enclosed and considered permanent.

Process heating can be: the use of heat to carry out a specific process such as industrial cooking, drying (including drying of wood and other biomass fuels), pasteurization or chemicals manufacture. Other examples include heat that is used for cooling, e.g. passing renewable heat through absorption chillers. Eligible sources of renewable heat are, the air for air to water heat pumps and water, ground or recovered heat for ground source installations. Recovered heat must not exceed 2/5 the of the entire heat production.

For adsorption equipment, the important section for the RHI grant is the lower temperatures of adsorption machines working down to 50 degrees in association with Ground Source Heat Pumps and are therefore entirely suitable for RHI grants.

The renewable heat incentive is paid quarterly based on the measured amount of heat produced in the installation. Ground and water source installations attract a two-tier grant payment in the form of £0.0895 per Kw hour thermal for the first 1314 run hours per annum and £0.0267 for the remainder of the eligible heat production per annum. Air source installations attract a flat rate of £0.0257 Kw hour thermal per annum. The tariff levels increase each year currently matching the RPI inflationary index.



Friday, 16 December 2016

Future perfect

Last week's #Build2Perform blog 'Back to the future' focussed on the future of Building Services, as told by our 'Are you ready for a digital future?' panel at the Conference and Exhibition. This month's podcast takes a look from another angle - by looking at the past. Principal of Atelier Ten Patrick Bellew and Max Fordham, Founder of Max Fordham LLP, are our speakers.



This Month's podcast featured extracts from the CIBSE Building Performance Conference and Exhibition session 'Celebrating Anniversaries & Sharing Aspirations', featuring Patrick Bellew and Max Fordham, and chaired by Peter Murray of New London Architecture.

This session focussed on the history of their two organisations, both industry heavyweights and CIBSE award winners in their own right, and what lessons they have learned over the years. As well as a look at the changes within the industry over the last 50 years, the session also took a look forward into the industry's future, as we try to apply what we've learned from technological revolutions in years past to the ones happening right now.

Here's some more information on some of the issues raised in the podcast:

  • Tamsin Tweddle outlines her work on Soft Landings in the Architect's Journal
  • The CIBSE Journal takes a look at Cundall's newly Well Certified offices in London, which incorporate high indoor air quality standards.
  • The #Build2Perform podcast hears from Conference speaker and sustainability consultant Julie Godefroy about indoor air quality.
  • BIM Consultant Carl Collins writes on how to use BIM more intelligently, and talks about it in our podcast 'Zen and the Art of BIM'


Friday, 9 December 2016

Back to the future

A month after the CIBSE Conference and Exhibition, CIBSE Communications Executive Matt Snowden takes a look back at the highlights of the session 'Are you ready for a digital future?' and examines what we learned.

When we take a step back and review the engineering industry it’s easy to take a look at the past and the future. We can look at the decisions and plans we made a week, a month or a year ago and take lessons from the good and bad things that resulted, and promise to learn from them. That’s all part of planning for the future, where we’re confident that these experiences will help us to avoid making mistakes and achieve our objectives.

What is much harder is examining what we are doing right now, particularly where technology is concerned, mostly because of a lack of data. At a time when new technology available to the engineering sector promises to revolutionise our jobs as much as when the computer replaced the drafting desk, it seems impossible to imagine that this might be holding us back rather than pushing us forward.

Talking about digital issues can focus too much on the tech, and
not enough on the user
That’s exactly what was discussed at the CIBSE Conference and Exhibition, during the session ‘Are you ready for a digital future’, but rather than focussing on the ‘business end’ of the issue – the technology itself – the session focussed on the ‘back end’ – the supply chain that is trying to use it. 

The result was some interesting points about what the supply chain actually wants from digital engineering, and how companies can overcome their own shortcomings to take full advantage.
Mike Darby, CEO & Co-Founder of Demand Logic, made a great point early on about the sheer volume of data available to engineers in the modern world. A lot has been said about big data in just about every industry there is, but built environment professionals are at the forefront of the biggest connected devices in the world – the buildings we live and work in.

He calculates that there are over 170,000 BIM data points in a new building like 20 Fenchurch Street (the Walkie Talkie) alone, bringing in spreadsheets worth of data every day, but that the human interface with this data creates a bottleneck. Every byte of that data is wasted, along with the resources expended to gather it, if it is not stored and used correctly at the user end. This amounts to a lot of waste, both potential and actual, and a lot of money thrown away as a result.

The 'Digital future' panel in action at the CIBSE Conference
One of the issues at play was raised afterwards by panellist Dave Mathews, a Partner at Hoare Lea, who said that we’re just not designing user-friendly systems that give simple feedback about their performance. This is an obvious problem, because users can’t act on what their building is telling them about its performance if they can’t understand what it’s telling them. This part is the responsibility of engineers, who can demonstrate their value to a project by working with the other stakeholders and the occupants to explain how a building works and why.

The job of the engineer shouldn't stop at handover
The job of the engineer doesn’t end when the keys to the building are handed over and everybody has moved in. Alex McLaren of Heriot-Watt University was on the panel, and believes that it’s her responsibility as an engineer to revisit the project periodically to check up on the tenants, and to see what lessons she can learn by the project in-use as well. According to Mike Darby, often the people in charge of maintaining the building and its performance just aren’t trained to a high enough standard to get the best use out of its systems.

By sticking with a project to make sure that everybody has enough information to run it properly afterwards, an engineer can ensure that issues that aren’t picked up in the six-week commissioning period don’t come back to haunt them later on. This can simply mean a handover period to explain why certain systems exist and how they work, or it can even mean a more in-depth training period to bring the maintenance staff up to speed. This sounds like a lot of work but, of course, there’s something in it for the engineer too. 

As Alex McLaren said in the panel: ‘Who remembers the engineer after the end of a project?’ You may not have your name stamped on the building like an architect would, but you can demonstrate continuous value to the project way beyond delivery by ensuring it works well.


Friday, 2 December 2016

Ties that bind

Last month, CIBSE and its American counterpart ASHRAE celebrated their 40th anniversary of working together at a ceremony in London, and also signed an agreement to work closer together. This week, CIBSE Communications Executive Matt Snowden (MS) and ASHRAE President Tim Wentz (TW) examine what that deal means in practice

TW: On the 40th Anniversary of ASHRAE/CIBSE collaboration, the two world-leading engineering organizations signed a Strategic Partnership Agreement. The agreement’s purpose is to provide a framework through which ASHRAE and CIBSE can work collaboratively to leverage each other’s strengths and accomplish organizational goals which best serve their respective members, the profession and society. 

The basic tenets of the agreement include:
  • Development of joint training and educational programs in Europe.
  • Exploring development of new conferences that accelerate technology dissemination.
  • Collaboration on research that will advance mutual member interests.
  • Coordination of research programs.
  • Mutual endorsement of conferences and exchange of technical expert speakers. 
  • Connecting of aligned membership demographics, such as Young Engineers in ASHRAE and the CIBSE Young Engineers Network.
  • Exploring opportunities to collaborate on technical publications and standards.
  • Commitment to annual volunteer or staff leadership meetings.
  • Annual staff exchanges.
ASHRAE President Prof Tim Wentz and CIBSE President John Field
 sign the agreement

What does this deal mean to the two organisations?

TW: Collaboration and sharing of knowledge are key to advancing the built environment industry. ASHRAE’s partnership with CIBSE over the last 40 years has proven to be an invaluable collaboration for our respective members and the industry at large. Our joint work through conferences, publications and education has greatly added to the worldwide best practices databank of innovative and successful technologies. I am pleased to celebrate this milestone and look forward to many more

MS: CIBSE and ASHRAE are two world-leading engineering organisations who bring many positives to the global building services industry, but at the same time have significant and positive differences. There are some instances where the task of tackling the problems which face the engineering industry will require us to work together, and times when it is better suited for us to work separately.

The worthy winner of CIBSE's graduate of the year award will attend this
year's ASHRAE winter conference in Las Vegas

Will this impact the way ASHRAE and CIBSE work with other organizations?

TW: No. ASHRAE and CIBSE both have unique relationships with organizations around the world, and that will continue. Additionally, the ASHRAE CIBSE strategy encourages working collaboratively with other organizations.

MS: One of the biggest strengths of the two organisations is their global reach, unaffected by borders, and their global network of collaborating partners. This agreement will not affect any of these relationships, and both CIBSE and ASHRAE will continue working in unique ways with these partners. In fact, this new agreement will help strengthen global collaboration with different partners, and emphasise collaboration as part of its strategy.

How will this impact members?

Members will benefit from the combined global
reach of both organisations
TW: How will members be impacted? Positively! Combining resources for common member goals and encouraging a global exchange of ideas and technologies will benefit all members. There are no immediate changes to benefits provided to either organization’s members. CIBSE and ASHRAE members already take advantage of a membership reciprocity agreement. The potential is enormous!

MS: As the only two organisations in our field with a global reach, CIBSE and ASHRAE have significant common ground and shared interests since the start of their excellent relationship 40 years ago.This new agreement will strengthen that relationship, and help spread the benefits it bring to both CIBSE and ASHRAE members, global partners and to the engineering industry as a whole. By finding opportunities to utilise and deploy both organisations separate resources, skills and expertise, CIBSE and ASHRAE will find new ways to tackle the issues facing the industry, expand our common goals and strengthen the synergy between the two.

Will joint programs be implemented in the U.S. and the UK? 

TW: There are no geographical boundaries on the collaborative programming. CIBSE and ASHRAE will align goals and resources wherever it best serves our respective members to do so. 

MS: One area of improvement will be in communication: Both organisations will ensure that the other is informed on major initiatives, and will work together to develop strategies to deploy these initiatives around the world. There will be an annual staff exchange, as well as an annual vision meeting to ensure that the two organisations become more closely aligned.

Collaboration will also benefit. Team working outcomes are normally better than working as individuals, and the agreement will pave the way for greater. This will benefit members, both societies and society in general. Collaboration between chapters and groups will ensure that those with similar remits in their respective regions will communicate closely and share knowledge, both organisations will work together in advocating building services related policies in their respective territories’ legislatures, and both organisations will create and cross-promote publications of mutual benefit in each other’s memberships.

Better communication and knowledge sharing between the two organisations
will benefit members
One of the two organisations’ great strengths is in their work within the engineering communities, and their existing network of relationships and collaborations through which they are able to make positive contributions to the industry. This agreement is the start of creating that framework to serve society and the profession more effectively in the future.

How can I get involved?

TW: ASHRAE and CIBSE are driven by volunteer expertise and leadership. There will be many opportunities for members to get involved as joint programs are implemented. Those interested in volunteering should send an email to ASHRAEPresident@ashrae.org or msnowden@CIBSE.org

Friday, 25 November 2016

Something in the air

One of the main topics at last week's CIBSE Building Performance Conference and Exhibition, indoor air quality is fast being recognised as a priority concern in the world of wellbeing. But in a field where marginal gains are everything, being on top of your data is very important Arie Taal from the Department of Mechanical Engineering at The Hague University has produced research into eliminating faults in HVAC using a BMS

Carbon Dioxide based demand control ventilation (DCV) can reduce heating/cooling loads by up to 30% and fan power consumption by up to 35%.  DCV maintains the CO2 concentration in a room within an appropriate range by adjusting the supply air flowrate.  CO2-based DCV is the most commonly used control method with CO2 sensors installed in the main return air duct.  Nowadays, the increased requirement for smart buildings, combined with a decrease of CO2 sensor prices, has resulted in buildings being equipped with more sensors.

A common issue occurs when one of the CO2 sensors encounters a fault.  This can be down to a lack of maintenance or incorrect sensor placements in rooms.  In a DCV system, a fault can mean that the estimated energy savings and air quality is not guaranteed.  In 1993 the Automatic Background Calibration (ABC) method was developed to calibrate CO2 sensors with the idea that CO2 levels would drop outside normal levels in buildings that are not occupied on weekends or weekday evenings. However, placement of sensors can become a problem as rooms on the inner side of a building or rooms with well-sealed windows may never drop outside of these baseline levels.
Properly controlled ventilation can have a big impact
 on a buidling's energy consumption
Alongside Dr Yang Zhao and Prof Wim Zeiler at the Department of the Built Environment, Eindhoven University in the Netherlands, Mr Taal has been working toward a systematic method of diagnosing faults in CO2 sensors.  Using automatic fault detection, diagnosis and self-correction in CO2 sensors would be a proactive method in air conditioning systems to solve this problem.  The premise of Mr Taal’s study has been to show how the automatic commissioning of CO2 sensors in air conditioning systems is achievable using benchmark values obtained in one of two methods.

In conventional methods, sensor faults are detected by comparing their measurements with benchmark values.  These values can be obtained manually, measured by technicians, or calculated automatically using other available measurements.  The latter is more common because it can be done automatically in the building management system (BMS).  Practical issues arise in air conditioning systems because there are no sensors equipped to measure the CO2 generation rate, CO2 concentration in the supply air and the flow rate of the supply air in m3/s.  In the development of models for CO2 sensor fault detection, the lack of information poses a real challenge.

It is important to test the sensors without
outdoor air, and with solely outdoor air
In an effort to eliminate the threat posed by this lack of information the idea is to perform one of two test methods under specific operating conditions to ascertain the required benchmark levels.

The first is to recycle air without adding any outdoor air for between one and two hours to create 100% return air ventilation.  By closing all windows, doors and fresh air dampers in air handling units the measurements of all CO2 sensors should theoretically be the same.  The second test is full outdoor ventilation, to supply fresh air into the building without any recycling for between one and two hours.  Again, at the end of the time period all of the CO2 sensors should be the same and equal the CO2 concentration of the ambient air.

Faulty sensors will be detected if their readings are different from the assessed benchmark values.  A faulty sensor can be detected if its measurements are obviously higher or lower than other sensors.



In the first method, the degree of fault is then measured from the difference between the defective sensor and the average measurement of the other faultless CO2 sensors. The second compares the faulty sensor reading to the ambient CO2 concentration both looking for a negative or positive bias in CO2 levels when measured against the benchmark.

Self-correction is the final step in the process where all of the information is taken from the faulty sensor for adjustment.  Using the assessment results from the fault diagnosis the CO2 bias can be corrected.  The results of the detection, diagnosis and self-correction will then be reported to technicians for reference.

Together with his team, Mr Taal produced a simulation of their works on the first floor of a school building at The Hague University in Delft.  In their experiment, nine rooms were used with a CO2-based DCV applied to control the amount of supply air to each room in order to keep the CO2 measurements within the benchmark.  Separate experiments were conducted to simulate different conditions. The first simulates a fault free operation and a second introduces faulty sensors to show the impacts of automatic fault detection system.

A potentially serious problem with an HVAC system can be detected
simply using a BMS

Using two operating methods to obtain CO2 benchmarks, 100% return air ventilation and full outdoor air ventilation; faulty sensors can be detected, diagnosed and self-corrected using a BMS.  From the simulations, results show that after 45 minutes there are obvious differences between functional sensors and those that are faulty.  After an hour and a half the positive or negative bias can be accurately measured.

Theoretically, the proposed methods are effective ways to detect faulty CO2 sensors, effectively diagnoses the state of failure and to automatically remove the fault.  The ability to automatically detect, diagnose and repair faults is vital to the effective running of DCV systems.