Energy Efficiency in Thermal Comfort- Passive Air Flow Principles

//Energy Efficiency in Thermal Comfort- Passive Air Flow Principles

Energy Efficiency in Thermal Comfort- Passive Air Flow Principles

Energy efficiency in design  is ensuring that the usage of energy in your building has been optimized to ensure that it is not wasteful or uncontrolled, but rather well regulated and made sustainable. The implications of energy efficient design are realized at the point whereby huge savings are made in the built environment simply because of the simple energy saving measures that have been put in place.

Energy Efficiency, Passive Air Flow Principles for Ventilation and Thermal Comfort.

 

energy efficient airflow through atriums

energy efficient airflow through an atrium

Many buildings in the developed world have been designed with strong emphasis on maximizing on views and optimizing on space use. The result of this is that some spaces such as toilets and storage facilities may end up being relegated to zones of the building that are not prime. In temperate countries, the requirement of harnessing natural light and views especially during winter means that some of these services are located adjacent to the building core to facilitate servicing requirements.

 

The current reliance on artificial systems is not energy efficient design.

However an intrinsic weakness of this model is its reliance on energy to ensure it works as required. Should there be a power failure, such facilities could cause inconvenience due to smell and noxious gases deep within the interior of the building. In addition, there is a lack of air flowing naturally deep into the spaces, which could again pose a challenge should there be any breakdown in the artificial ventilation systems employed.

 

Air flow within the building serves two purposes, namely provision of clean fresh air for occupants to breathe and assisting to regulate temperature and maintain it at comfortable levels. HVAC (heating, ventilation and air cooling) systems are installed to ensure that air flows properly within buildings, to create a comfortable internal environment having fresh air for users.

 

Today’s buildings have become larger and more sophisticated than in the past, and many modern day developers are interested in offering huge internal spaces for commercial developments. It is commonplace to see mega malls that are completely internal in their orientation, having very few external openings in proportion to the building’s size. Office spaces compete to offer best views and daylight within a space, with a view to optimize on lettable area.

 

Undoubtedly, these trends have led to heavy reliance on artificial ventilation as the means to provide air within these large structures. In addition, air conditioning has become a major requirement in many urban areas as they are the only way of regulating internal air and thermal conditions inside such large structures. The energy load required by these buildings is a formidable one, and become a huge drain on national energy resources.

 

While it is impossible to halt the creation of huge structures to meet the demand of users worldwide, it is possible to ensure that they are created in a manner as to exert the least energy loads possible as regards artificial ventilation. This is where principles of green architecture come in to assist the energy efficiency conscious architect.

 

Energy Efficient Ventilation – The Chimney Effect

Mother nature has gifted us with a natural law of physics which states that ‘hot air rises, while cold air flows’. This principle of convectional flow of air is present in the physical world, and an architect can harness it to enhance the flow of air within a space. In this manner, an architect designs a facility with the ability to allow hot air within to escape upwards, while at the same time allowing cool air to be drawn naturally into a space.

The architect can create a space that has an atrium or upward channels, with inlets at the lower levels of the space that allow for fresh air to be drawn in. At the highest point, an opening can be created to ensure that hot air rising up the atrium or ducts can escape into the atmosphere. This is called the ‘chimney effect’.

As the hot air rises up, it creates a zone of low air pressure at the lower levels of the space (where users work, live, shop or eat) and nature duly acts to equalize this low pressure by drawing in fresh cool air from outside to fill the gap. As a result a continuous natural air flow draft is created, as hot air breathed out by occupants of a space is exhausted upwards, and cool fresh air is drawn in.

 

The power of this chimney effect can be felt especially in large malls that have high-level openings and atriums, connected by several low level openings. The natural draft ensures that there is a cool flow of air within the buildings, and successfully ventilates the buildings naturally. This definitely is an advantage over other buildings that completely artificially ventilate and cool their interiors.

 

In temperate countries, this principle can be utilized during summer, while the heating can be maintained during winter. In essence the energy loads attributable to ventilation and cooling are major, and these can be avoided when necessary. In the tropics however, this system can be used throughout the year, resulting in drastically lower energy requirements than a fully air conditioned facility. In each case, huge savings can be realized as the recurrent costs of keeping a HVAC plant going can be hugely reduced during the lifespan of the building.

 

Energy Efficiency in Ventilation – use of narrower floor plates

Another factor that architects should note that can assist in natural passive airflow in a building is by designing buildings with narrower floor area aspect. When buildings are created to be deep, certain zones of the building become too distant from the external windows and vent openings. These zones have to be served with air that has been artificially channeled to them, either through air conditioning or mechanical ventilation.

 

Having a building designed with narrower floors will ensure that air can naturally be drawn from one side of it to the other easily, leaving no dead space within. In addition, one can provide low level vents on one side and high-level outlets on the other, allowing air to be drawn naturally from one end to the other. This greatly assists in airflow within a room. This can be further enhanced by single banking the spaces (having a single row of usable rooms), or combining rooms with the atrium chimney effect to ensure that air flows across rooms, up and out of the building.

 

Energy Efficient design creates green architecture

Use of natural principles will enhance the flow of air within a building’s interiors. Achieving natural ventilation will ultimately reduce the recurrent costs of a building throughout its lifespan. An architect who achieves energy efficiency in design is sure to have created a sustainable building that will stand the test of time.

By |2011-07-25T18:05:45+03:00July 25th, 2011|Green Architecture|0 Comments

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