What is sustainable design in air conditioning?

By: Camilo Botero*

It is a rather complex question to answer, but an answer could be ventured saying that it is one that takes into account the best energy efficiency of the equipment that makes up the different systems involved in an air conditioning project, accompanied by a high awareness of the environment, climate change and that complies with the quality of the air inside the enclosure. All this in accordance with the rules that regulate every aspect of the design, operation and maintenance of the systems.

Sustainable energy is energy produced and used in a way that guarantees human development in all its social, economic and environmental dimensions.

Some clarifications

I will refer throughout this article to the speech by Gordon V.R. Holness, P.E. current president of ASHRAE, published in the August magazine of that association, who describes the theme as follows: "Sustaining our future, rebuilding the past."

There he presents the sustainability plan and the vision towards 2020, based on six key points:

1. The Advanced Guides for Energy Design (AEDG) series
2. The 90.1 Standard: Energy Standard for Buildings .
3. Standard 189.1: Standard for the design of green buildings
High Performance
4. Standard 100: Energy Conservation in Existing Buildings.
5. Commissioning and Retrocommissioning Guidelines.
6. Operation and Maintenance Guidelines

Commisioning, which does not yet have an accurate translation in Spanish, is to ensure that what was designed and installed, continues to have an efficient performance over time. Most buildings decrease their performance by up to 30% in the first three to four years due to operation and maintenance failures.

In general in Colombia we are far from these objectives, however
a program of translation of the most widely used standards in our country has been initiated with relative success.

• 15. Standard for refrigeration safety systems.

• 52. Procedures for testing air filtration devices.

• 55. Environmental conditions for human occupation.

• 62. Ventilation for acceptable indoor air quality conditions.

• 90 Energy standard in buildings.

Existing buildings

According to the data that appear in the aforementioned speech, existing residential and commercial buildings consume more than 72% of all electricity generation and 55% of natural gas consumption.

The Advanced Energy Design Guides (AEDG) series recommends a use of 26,700 Btu/ft² – year i.e. approximately 221,490 Btu/mt² – per year, for 2010. It is well worth each of us to research our sites of occupation and our designs at what level of energy use we are.

We do not have in Colombia precise data of these proportional consumptions but I know from my own experience that in the warehouses of large surfaces, 80% of the electricity bill is represented by air conditioning and refrigeration. In candy plants in hot climates that value is 60% and also in pharmaceutical laboratories you can talk about similar figures.

These data lead us to conclude that the great effort in sustainable design, including the items listed at the beginning, must be made in existing buildings, including industrial plants, to reduce energy consumption and minimize the carbon footprint that impacts the environment.

Training and control

All of the above presupposes a great effort in the dissemination of these standards and methodologies and other intensive training programs that make our engineers and technicians have the necessary and updated preparation in such a way that they appropriate all the technologies that have to do with more efficient equipment, their design, application and become tools of daily use.

In his speech, the president of ASHRAE highlights the following in front of the commission:

• Promote the importance of commissioning.

• Provide training through ASHRAE chapters.

• Offer educational programs.

• Provide certification programs.

• Continue with the development of commissioning guides.

• Provide training through ASHRAE chapters

• Offer educational programs.

• Encourage certification programs.

Another fundamental aspect in this process is to incorporate the greatest amount of control in the systems so that they adapt to the partial loads and only the necessary energy is consumed depending on the building.

Renewable energies

If we act now we can create energy systems that lead us to a fairer, more environmentally logical and more economically viable world, warns the World Energy Council.

This solution includes:

• Promotion of energy efficiency.

• Use of renewable energies and advanced technologies.

• Aid to developing countries.

In contrast, renewables have the potential to provide energy services with zero or almost zero emissions. They currently account for 14 per cent of the world's total energy demand and should be greatly encouraged. Among them we highlight biomass, solar, wind, geothermal and hydroelectric energy.

In the case of Colombia, the alternative sources with the highest employment are:

• Biomass for heat production.

• Small-scale hydropower.

• Pumping through the use of wind energy.

• Solar for heating and drying.

• Some biogas applications.

*About the author

Camilo Botero is the current president of ACAIRE and president of Camilo Botero Ingenieros Consultores Ltda. He has worked as a teacher in several Colombian universities, guilds and currently in ACAIRE in diploma courses of air conditioning projects, energy efficiency in air conditioning and refrigeration, cogeneration and trigeneration, applied psychometrics, thermodynamics, fluid mechanics, heat transfer and turbomachinery.