TM44 stands for Technical Memorandum 44, which is a guidance document for inspection of air conditioning systems published by CIBCE (the Chartered Institute of Building Services Engineers).  It is aimed at compliance with the Energy Performance of Buildings Directive 2002 and recast in 2012.  This is a European directive for all member states to establish regular inspections on air conditioning systems of more than 12kW.

So if you have a building with HVAC systems containing cooling plant of 12kW or more then you should undertake regular inspections of them.  The inspections are aimed at reduction of energy consumption and associated costs

Our team of building services engineers can undertake air conditioning inspections in line with TM44 and thus meet the requirements of the EPBD.  Where significant opportunities are identified they are often built into asset lifecycle replacement strategies and / or review of the purposes of the air conditioning systems.  This is especially relevant to laboratory categories and their very specific risk assessments that define their ventilation, heating and Air conditioning requirements. 

HVAC stands for Heating Ventilation and Air Conditioning.  This is a generic acronym for all aspects of heating, cooling & ventilation.  This can include simple natural ventilation approaches with almost domestic central heating systems to large district heating and cooling mains across whole campus of complex buildings. 

Heating systems can include gas boilers, refrigeration based heat pumps, ground thermal systems, biomass plant and Combined Heating and Power (CHP) systems.  Many large buildings still use gas fired boilers, often quite old and thus of poor efficiency.  A key part of such a system is the distribution of heat across what is often a highly adapted and extended pipework distribution system.  Often including calorifiers or heat exchangers to separate pressures and circuits.  Plus extensive pumping arrangements.  Common issues in these systems include un-balanced distribution of heating flow, short circuiting, over pumping, poor water quality etc.  These often combine to cause very little differences in flow from and return to the boiler temperatures.  Boilers don’t work well when they are only bringing water temperature up in small amounts.  They are typically most efficient with temperature differences of 10degrees or more.  Add to this the use of old technology, with very low base efficiency and you have a recipe for massive overuse of gas.  Other issues can include starvation at the extremities of the systems, leaving parts of a campus or building without heating.  Still other issues relate to the still to common use of high temperature or pressure hot water (HTHW or HPHW), which brings significant cost of plant and compliance issues with the Pressure Systems Safety Regulations 2000.

Chilling systems can be connected to a water circuit or distribute cooling directly via the refrigerant.  Typically larger chilling systems are water circuit based and have similar issues to heating but run on electricity instead of fossil fuels.  Newer technology in refrigeration also enables very high efficiencies, in some cases reaching six or more cooling kW’s for each electrical kW consumed.  Thus they can be very efficient.  Large chillers can either be water cooled via cooling towers or more frequently air cooled by passing air through large radiator systems.  Many older chillers are not specified for the type of ambient temperatures that we see these days and if positioned in direct sunlight, they overheat and cannot eliminate heat from the refrigerant.  This increases internal pressure, which takes more energy to compress back into liquid, but for less cooling capacity.  Thus older chillers can be highly inefficient. 

Heat pumps.  These are refrigerant bases pumps that can reverse.  They can take heat from the environment and put it into a hot circuit or alternatively take heat from a cold circuit and eliminate it into the environment.  Thus enabling either heating or cooling from the same device.  These are very popular alternatives to gas fired boilers now and many devices are now on the market.  However heat produced is far less than a conventional boiler.  Thus adaptation of old systems to this type of heating requires re-engineering.  This can mean larger heating coils to pass heat into airflows over a larger surface area.  Or can mean programming the system to stay on for longer, thus heating over more time.  If hot water circuits serve domestic hot water cylinders, then they often require electrical top up to reach legionella pasteurisation temperatures.

Ventilation.  Large air handling systems can be massive energy loads in a building.  Especially if set up for too much air flow and / or too much fresh air.  Historically air handling units are designed to maximum heating, cooling and air flow needs.  Factors of safety are also applied in a chain from client requirements, principle contractor, designer and manufacturer.  Typically buildings operate at a fraction of their maximum occupancy, especially with the prevalence of remote working.  Thus ventilation systems for people are often very oversized or more frequently over supplying air unnecessarily.  Most fresh air settings are also designed for maximum occupancy, thus too much fresh air is drawn into the system.  These items greatly increase energy used to move air (fan power) and in heating or cooling external air.  Which in the extremes of summer or winter can easily go outside of the system’s ability to cool or heat enough air.  Thus leading to too hot and too cold conditions.  During Covid-19, guidance was issued for operators to run their ventilation at full fresh air and extract and to extend operating times.  This uses far more energy by heating and cooling more external air, never reusing it and leaves it running for longer.  Many companies have not reset their systems since Covid-19 and are thus consuming far more energy than previously. 

The areas above represent the primary hardware that we focus on when looking for HVAC energy opportunities.  Often, we find building integrity issues as problems are identified.  These represent another category of saving and business investment.  Typically opportunity in energy savings through HVAC are significant, with typical savings of 30-80%. 

Most large commercial buildings have what is called a BMS (Building Management System).  Basically this is a computer system that runs the building and interfaces with HVAC, domestic hot water systems, sometimes lighting, security, fire and other services.  These systems are often old and set up with logic from 30 or more years ago.  They rely on sensors and control devices to adjust equipment in real time.  A combination of old control logic, malfunctioning sensors and failing control devices often combine to create significant waste of energy.  Often the control strategy programmed into the BMS is lost.  In some cases this can be downloaded from the system, in others it is down to engineers to extrapolate it retrospectively. 

When building control is combined with our HVAC optimisation approach, we can achieve very significant savings.  If optimisation is identified in the BMS, the return on investment time is often measured in months, whereas hardware upgrades are more likely to be in years.

Heating ventilation and air conditioning systems are typically on at a near constant operating condition.  They are usually designed to supply air within set parameters of temperature, humidity and fresh air at either constant flow or pressure.  As stated above in HVAC optimisation, these settings are usually for worst case maximum occupancy conditions. 

But most occupancy numbers are far lower and much more variable than they used to be.  With buildings operating at full ventilation, heating and cooling throughout operational hours. 

On demand HVAC, ramps the systems in concert with its occupancy and need.  in effect the building breathes with its occupants.  Modern sensing technologies can detect occupants and their location in the building.  Air quality sensing can detect if there is sufficient clean air or fresh air.  These inputs can be combined into more advanced building control algorithms to focus air where it needs to be, reduce air flows when not needed, modulate fresh air to match the occupancy levels and even anticipate additional cooling, heating or fresh air needs in advance of any noticeable effects by the occupants. 

During the Covid-19 pandemic, guidance was issued to alter HVAC equipment to full fresh air and extract and to extend operating times.  This was to provide a dilution strategy for indoor airborne pathogens, including coronavirus.  This massively increased the energy used to heat, cool and ventilate buildings across the country. 

During 2020 & 2021 AcuFireUK Limited led an Innovate UK project to look at using medical air sterilising technologies used for infection control to re-enable recirculation and provide better indoor air quality and pathogen control than simple air dilution.  Also enabling recirculation strategies and on demand strategies to address spiralling energy use.  This project was 78319: Covid safe & Energy Efficient Ventilation.  This concluded successfully in June 2021 after detailed testing on several different sites. 

The project was undertaken with two partner companies, SRS works and Lightfi.  It was also carried out with support from the Active Building Centre which is a government funded building best practice and research organisation. 

Three technologies were considered:

• UV-C (Ultraviolet C spectrum), also known as UVGI (Ultraviolet Germicidal Irradiation)
• Bi-polar ionisation
• UV-PCO ultraviolet photocatalysis

UV-C and Bi-polar ionisation were both tested live and proved highly effective in treating air within the ventilation plant itself but more importantly within the live conditioned space.   UV-PCO was not taken forward to trial, due to concerns with the safe use of the product.

UV-C and bi-polar ionisation are ideal technologies to use in any facility where occupants or business process require protection from airborne biological pathogens.  These technologies enable the use of recirculation where otherwise guidance may require full fresh air and extract. 

The biggest influence on energy use is often not the Building Management System, the Air conditioning or the type of light bulbs you have fitted.  It’s usually your staff.  Energy is consumed usually in direct ratio to the core business.  If your people are on board with reducing energy, carbon emissions, saving water, etc., then you will.  The larger the organisation, the larger this effect.  But unfortunately the larger the cultural change that may be required. 

However with energy costs rising and awareness of environmental issues and goals regularly in the news, energy change is at a tipping point in our society.  Hence bringing your team on the journey might not be as hard as you think. 

AcuFireUK have worked for many years with The Discovery Mill in this field and across a range of sectors.
We recommend that if your serious about saving energy, then you need embrace your company culture and adopt an energy behavioural change initiative. 

Please contact us or the discovery mill directly to discuss this further.