The precept of attaining energy efficiency when constructing a building in Kenya is to ensure that it applies energy within it in a manner that is efficient and well governed. By seeing to it that a building does not squander energy, it becomes more sustainable as spends less on energy in the course of its lifespan.

Energy Efficiency Through Ensuring Thermal Comfort And Natural Ventilation

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.

One major weakness of having systems that are wholly reliant on energy to work is the fact that if there is a power failure, these systems would fail. The result of this is that there would be huge inconveniences due to smell and lack of ventilation in these spaces which are served by artificial ventilation systems.

Buildings must provide adequate air flow within them mainly for two reasons – provision of fresh air which is a basic life necessity, and to regulate interior temperatures by retaining it within human comfort levels. Any artificial ventilation systems or mechanical ventilation that is installed within a building seeks to ensure that there is proper airflow and comfortable indoor environmental quality through the quality of air experienced within.

It is common to see today’s interior spaces being modelled with an emphasis on provision of maximum lettable area, and having very deep interior spaces that cater for large scale activities within. The level of sophistication of these spaces has also increased, as one can witness in massive shopping malls or large office spaces offering huge interior spaces. These spaces will tend to be oriented towards their interior and only in office blocks will one witness an effort to harness day lighting.

Design trends that shun natural ventilation methods invariably place a major demand on the need to artificially enhance the flow of fresh and clean air within the interiors of such buildings. The means to achieve this is use of artificial air conditioning systems that will circulate air within building interiors. However, these systems require the provision of continuous energy supply, and this can be a substantial cost to cater for during the life of the building.

Achieving natural energy efficient ventilation through using the chimney effect

Hot air rises, while colder air falls. This principle of nature is what is applied using the chimney effect, as hot air that has been warmed by occupants within buildings can be provided with a vertical channel with which it can flow upwards and outwards. As this happens, cooler air is naturally drawn in at the base levels of a space to fill in the vacuum that has been left by the escaping warmer air upwards. This creates a natural heat exchange process using air.A space can be designed by an architect to have a vertical stack at its core that flows all the way to the top of the building. This stack is connected with lower level openings or inlets, which could be actual doors, or simple vents that are strategically placed to suck in air into the central shaft. The stack has an opening at the top to let out warm air that is drawn up the vertical opening as it rises to the top. This is the phenomenon of 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.

Use of the chimney effect can be effected in various climatic conditions, all with the need to reduce the need to rely on artificial air conditioning. Temperate countries can use this to regulate building interior temperatures during warm summers, while tropical conditions can allow this to be used throughout the year. In so doing, a building’s running costs can be greatly reduced as one is able to achieve good interior environmental comfort using natural air flow systems. This greatly enhances a building’s sustainability.