New and innovative techniques in climate separation supports ‘green’ thinking

By Robert J Schomaker, Biddle BV

Rising energy costs and demands for higher standards for comfort in indoor climate, have forced designers to come up with new construction methods and materials for modern buildings. These innovations have made it possible to house people in extreme climates with high comforts.

Unfortunately still a lot of energy is lost at places where people enter these buildings. A long time it was thought that blowing a strong flow of air with an air curtain was sufficient to stop the hot outside air from entering the building but actually these curtains often make the situation worse. Each door opening is different and requires a specific solution. Biddle, a Dutch manufacturer of innovative climate separation equipment studied the problems and developed new techniques for optimum and efficient climate separation. These Biddle solutions that contribute substantially to the Green building concept are now available!

In past centuries people settled in areas where they could survive from extreme weather conditions without any special measures. In cases where a shelter was needed against cold or heat, simple materials like stone, wood or anything else nature had available was used to build a place to live. In modern times mankind is able to withstand the forces of nature by using any kind of material one can think of to build houses, offices and shops, whether this is in the burning heat of the desert or in the biting cold in the Arctic regions. Good examples of recent innovative technologies in building materials and construction techniques are the ski domes that can be found in the desert where enormous temperatures are bridged with just a few centimeters of isolating materials. These fantastic inventions allow people to live in places where one would normally not survive for long. Unfortunately all of these buildings need an entrance where people have access to these buildings. Let’s take a shopping mall as example. Many shops are located inside these malls and usually the access to the central space, connecting all these shops is one single large door opening. As the mall is conditioned, the temperature difference between inside and outside is often huge and can easily reach 25°C or more. As a result of this temperature difference, inside and outside air start to mix and consequently, enormous amounts of energy are lost. Maybe even worse, outside air, containing dust, moisture and insects enter the building causing the quality of air to be spoiled. Quite often entrances lead to a car park which brings another unpleasant effect; exhaust fumes! Let’s have a closer look at this effect of mixing air and the solutions that can be offered by Biddle.

Convection of air causes energy loss and poor quality of air
When two areas with different temperatures are connected by means of a door opening there will most probably be a temperature difference between these rooms. As a consequence of this ∆T colder air will creep over the lower parts towards the warmer area and warmer air (which is lighter) will lift through the upper part of the opening towards the colder room. This temperature- or energy exchange is called convection and this effect occurs as soon as there is a temperature difference, no matter how small or big. Often this effect is underestimated. A 3 by 3 meter door opening between a conditioned space of 20°C and an outside space with a temperature of 40°C already causes a constant flow of lost energy of around 60 KW! This is a very common situation in many areas in the MENA region. The effect can be seen in doorways in shopping malls and other public buildings as well as in industrial sites, chill rooms and cold stores. The convection flow makes air to move. With this moving air also unwanted side effects occur. As warm air is drawn into a building, also car exhaust gasses and dust from the street can be drawn into a building. As quite often shop personal work close to the door opening this can cause illness and unhappy (= unfriendly) people. The energy losses boost the energy bill and affect the energy label of the building. In addition, the temperature inside the building rises and causes discomfort. In buildings for food storage (chilled or frozen) the rising temperature causes products to decay and HACCP regulations to be violated. The moisture which is drawn with the warm air into these cold rooms is causing mist and icing of walls, ceiling, refrigeration equipment and also on the products. High energy bills and maintenance costs and even dangerous situations are the result. Penetration of warm and humid air (especially in coastal areas) into conditioned areas cause an extra problem; in order to cool down this humid air, much more energy needs to be used to ‘dry’ the air and to take measures to eliminate condensation. In the above mentioned example of a 3 by 3 meter door the latent heat including moisture may need up to 300KW cooling capacity to be pumped away. This simple example shows how important effective climate separation can be and why this issue should be taken more serious in the green building concept!

Air curtains vs real climate separation
The energy losses through an open door are not often seen as a real problem. This can be seen in practice as many buildings do not have a good working solution at the door to prevent penetration of outside air. Even in prestigious and modern buildings small ‘hair dryer’ air curtains that make a lot of noise but have no effect, are installed over the door. But why spending millions in isolating buildings and installing high energy efficient cooling equipment while at the same time a lot of energy is lost through the open doorway? That the effect of convection is not really understood yet can be seen in the solutions that have been installed in many of the (old and new) buildings so far: cheap, simple, too small and often very fast blowing, noisy air curtains or something similar that blows air. The way these units work is simple; it is a longitudal fan driven by a small motor, built inside a plastic or steel housing, taking air from the inside and blowing it down to the ground. As the air, leaving the unit, is very turbulent (due to the high speed and lack of any pressure chamber or rectifying tool) the effect is rather negative than positive. Instead of creating a barrier between warm and cooled air, it mixes both due to its turbulent behavior. When the air flow hits the floor with high velocity it also blows up dust and takes it inside the building. The effect of these ‘air curtains’ is therefore very doubtful.

Biddle believes that real climate separation starts with understanding the effect of convection and moving air. Due to the substantial pressure, caused by the convection forces, an attempt to block this force only works if the strength or impulse of the air from an air curtain is strong enough. The speed however is also very critical and should be enough to bring the flow of air down to the ground but gentle enough, not to bounce on the floor or to cause turbulence to occur. A 10 cm wide laminar stream of air with a velocity around 4 – 6 meter/sec is perfect for a door height between 2.5 and 3 meter. Controlling the flow of air from an air curtain is therefore critical and this makes real functioning of air curtains a very serious matter. In addition the air flow should enclose the whole door opening (no gaps) and be mounted as close as possible to the door to prevent leaks or ‘false air’. As every door is different and as the strength or impulse of the curtain needs to be adjusted to the situation around the door (temperatures, location etc.) real climate separation has become a specialist’s job. Biddle is considered such a specialist due to numerous research projects and over 50 years of practical experience. In Europe traditionally air curtains have been applied already for many years due to the more severe climate and the costs of energy. In addition, there is a very high demand for comfort and open door trading (to invite people to enter their shop) is very common. Governments have supported the development of new and innovative techniques and solutions and with subsidies on the most effective equipment they push shop owners to invest in these solutions and to save energy. It is therefore no surprise that the patented Biddle technology to achieve real climate separation with over 90% efficiency (laminar stream technology) is widely available and now also slowly reaching the MENA region. Modern fully automatic controls bring the equipment to live and add intelligence to the units. Air velocity, impulse and (if needed) heating capacity can automatically be adjusted to the need, day and night, summer and winter and even remote monitoring of the units functioning can be done via Internet telemetry.
 
Companies in the NEMA region can benefit from real climate separation
Let’s have a closer look at the benefits of applying real climate separation for the different building segments in the MENA region.

Public/commercial sector
Great efforts are spend in maintaining a comfortable indoor climate in public buildings. However, due to the high flow of traffic through doors the indoor climate is seriously affected by the outdoor heat and moisture. Proper climate separation (tailor made solutions) can substantially reduce this negative effect, save energy, reduce disturbing noise from air conditioning equipment and noisy fast blowing ‘box-standard air curtains’. As a result visitors and customers can enter a public building or shop unhindered whilst the indoor climate is kept optimal at minimum costs and disturbance.

Industry
So far, industrial buildings have a low level of climate control. As these buildings are often huge in volume it is nearly impossible to achieve effective climate control. Nevertheless there can be a need in certain buildings due to the nature of the production process (chemicals, painting rooms, pharmaceuticals, food processing) to maintain stable temperatures and clean air. In these situations Biddle air curtains with laminar air flow can bring great benefits when installed properly at door openings which connect buildings to each other or to the outside (loading docks). Even the smallest temperature difference between two rooms will cause the air to flow from one room to the other and this can be prevented very successful by separating the climates using a laminar flow of air. The laminar flow is a guarantee for minimum turbulence and hence low or no contamination of the clean air.

Food storage/cold sector
Due to an even stronger concentration of people in the major cities, storage and logistics of (frozen) food is more and more important. New massive cold stores and chill rooms are being built but especially in hot and humid regions (Gulf and coastal area’s) the huge difference in outside and inside climate puts designers to enormous challenges in the design of these facilities. Especially the humidity causes problems in cold stores. It accumulates as ice on the evaporators and reduces the efficiency and capacity of the coolers. Ice builds up on doors which don’t close properly anymore and further loss of energy is the result. Biddle developed a new very special Multi Stream air curtain to deal with moisture and prevent ice build-up whilst at the same time offering an open doorway to the cold store without any plastic strips or energy losses. An excellent solution for those who take their business serious!

Smoke/odor
New legislation on smoking has forced the owners of public buildings to come up with solutions. Tests with laminar air flows in separated areas for smoking people, with a proper exhaust have proven to be more effective than a solid door. An air flow is effective at all time while a door is only effective when closed. But of course a door needs to be opened from time to time to let people enter and leave. This is where the air curtain wins. Biddle has developed special low-impulse air curtains for this application; however, understanding the technique of smoke separation is the real way to offer successful solutions. Waste management is a hot issue at the moment. Waste materials are more and more separated for re-use and all what remains is increasingly used in special burning facilities to generate electricity. These waste processing facilities often suffer from strict environmental laws. Bad odor is one of the negative side products of these plants and even if a strong exhaust system with carbon filters is installed, still a bad smell can be noticed around the factory, this again due to convection of air through the doorways. New Biddle techniques with strong impulse laminar flow air curtains can solve these problems.

Conclusion
In all of these afore mentioned applications true climate separation plays an important role in the building climate system, far more than what’s often seen in today’s designs. Future ‘green’ designs therefore should consider applying these new techniques and investors should understand that spending a little more on proper equipment pays off immediately in a much better climate and lower energy usage. By including climate separation in the energy calculations of tomorrow’s buildings in an early design stage, real working solutions can be developed and substantial savings become reality. The equipment can become part of the Building Management System thanks to modern controls. Do you want to know how you can optimize the indoor climate in your building and at the same time realize substantial savings on energy costs? We would be pleased to advice you.

Robert J Schomaker is Managing Director of Biddle Export Worldwide bv The Netherlands.

Contact details:
Robert J Schomaker, MD Biddle Export
T: +31-512-335524, E: mena@biddle.nl, W: www.biddle.info