The effectiveness of combining heating and ventilation
Published: 01 December, 2016
Proper ventilation is essential to maintaining good air quality in any environment. There’s no excuse for poor air circulation, especially since, when it can be effectively integrated with the heating system, as Dave Garvey of Nordair Niche explains.
In commercial buildings, good ventilation will keep bad odours, irritating pollutants and potentially harmful gases like carbon monoxide at bay. Plus, it prevents the formation of mould and/or mildew, which is vital for employee health and building hygiene — especially important when in a kitchen or food processing environment.
When production processes get underway, air quality can quickly deteriorate. Raised levels of indoor air pollution may reduce productivity, as well as having negative effects on the comfort of the building’s occupants. Certain industries are prone to airborne particles that can make life very unpleasant. Automotive manufacturing processes, for example, produce oil haze that hangs in the air. In other industries, chemical processes may generate foul vapours.
The use of chemicals or other hazardous substances at work can put people’s health at risk. Diseases such asthma, dermatitis or cancer can result from poor ventilation. The COSHH (Control of Substances Hazardous to Health) Regulations require employers to control substances that can harm workers' health. As a minimum, ‘a good standard of general ventilation and good working practice’ is required. For very hazardous substances, extract ventilation is often required, but a good level of ventilation that will maintain air quality can be achieved easily and cheaply — and without the need for additional equipment — through the heating system.
Combined heating and ventilation solutions have been on the market for many years. The technology has been developed to the point that they now offer optimum energy efficiency while improving air quality.
These systems rely on a degree of fresh air intake to operate. Nordair Niche direct and indirect gas-fired units, for example, provide both fresh and warm air in the building. Direct-fired units work on a patented air-recirculation system that supplies the amount of fresh air required to meet the changing requirements of the building while maintaining a constant supply of fresh air into the burner.
When fresh air is required, ventilation is quickly achieved, as the dampers automatically adjust to provide the required amount of tempered outside air. The effect is almost instant as the fresh air is distributed evenly around the building.
Since fresh air is delivered faster than it can escape by natural ventilation, these units slightly pressurise the air inside a building. Pressurisation causes the air to distribute evenly throughout, eliminating temperature stratification or ‘cold spots’ and ensuring every part of the building is usable at all times. Once optimum conditions have been reached, the system modulates the fresh air input and utilises up to 80% recirculated air for maximum economy.
When temperatures within the building change, a combined heating and ventilation system can respond very quickly, soon returning the interior to comfort conditions. Heat recovery is fast becoming the norm for such ventilation systems, reducing both running costs and CO2 emissions into the atmosphere.
This method of heating and ventilating premises does not require ductwork and is ideal for buildings requiring summer ventilation and regular air changes to maintain good air quality.
Combining heating and ventilation functions gives optimum control and avoids the problem of co-ordinating and balancing separate heating and ventilation units. The combined system also has significant benefits on the operation of the heating, since the system utilises a large air volume/low discharge temperature principle.
A modulating burner and damper system, controlled electronically, ensures full co-ordination of the heating and ventilation functions. Between 20 and 100% fresh air may be utilised together with up to 80% recirculated air. The 80/20 operation ensures excellent performance and low emissions.
Working with Mitsubishi Electric, Nortek developed a bespoke heating, ventilation and cooling system solution for McDonald’s Restaurants that reduced running costs, was transferable across sites and improved customer experiences with a reliable, consistent and comfortable temperature inside all restaurants.
McDonald’s Restaurants was looking to create a comfortable environment for customers through a more energy efficient heating, ventilation and cooling system, The new air-handling unit from Nordair Niche is used for cooling, heating and ventilation and resulted in McDonalds Restaurants cutting running costs by over £4500 for each site, whilst reducing carbon emissions significantly. There was also a 35% reduction in energy consumption across 250 UK restaurants following the installation of the air-handling unit developed by Nortek and Mitsubishi Electric.
Dave Holden, project manager for McDonald’s, said, ‘It is commercially critical for us to operate effectively all year round. Our customers expect McDonald’s to have a comfortable internal temperature, and the ability to offer that, reliably and consistently, is part of our relationship with customers.
‘When we started looking at replacing our air-conditioning equipment we quickly realised we needed a bespoke system. We were coming at this with very specific requirements, and off-the-shelf systems didn’t satisfy the need.”
The innovative solution combined Nordair Niche’s IDF air-handling units with Mitsubishi Electric’s air-source heat pumps, which were controlled by a Trend building energy management system to maximise operating efficiency.
An initial trial in two restaurants achieved an annual saving of £4515 and, on average, 20 t less CO2 emitted. The solution was designed to accommodate a variety of standard sized air-handling units previously installed so that the replacement solution could be rolled out across all 1200 restaurants.
Intelligent combined heating and ventilation units are also an ideal cost-effective and fuel-efficient solution for a variety of industrial applications, warehouse and logistics, bars and restaurants.
Dave Garvey is with Nordair Niche.
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