First part of this special on how to design, install, operate and maintain high-performance air conditioning systems.
By Camilo Botero*
Dear readers again at the request of the Editor of the journal, who suggested me to write this column, after reading the name of the course that I will teach with a similar name with which I title this article, I found it an interesting challenge in addition to forcing me to meditate on the content of said course at the IV International Congress of Air Conditioning & Refrigeration on during ExpoAcaire 2017 in Cali.
To start one could ask what are high performance air conditioning systems and one could answer that they are those that meet the following conditions:
Ideal air conditioning project:
- Maximum Energy Efficiency.
- Minimal Impact on the Environment
- Compliance with Owner Requirements for rdp Project
- Ease of Operation
- O&M (Operation and Maintenance) Maintainability
- Stability during its Life Cycle
The fundamental answer to achieve the above, in addition to others that we will discuss in this column, is given by the ASHRAE Standard 202 – 2013 on commissioning in air conditioning systems, which in its prologue defines it as:
"A quality-oriented process to optimize the delivery of a project. The process focuses on evaluating and documenting that all systems and assemblies are planned, designed, installed, tested, operated and maintained to meet the Owner's Requirements for the Project." It is a quality-focused process to improve the delivery and O&M of a project.
It is therefore a process that focuses on verification and documentation so that the installation and all systems, are planned, designed, installed, tested, operated and maintained to meet the requirements of the RDP owner, worth the redundancy.
In any project there are four very defined phases, which must have a quality assurance process:
- Pre-design
- Design
- Construction
- Occupancy, O&M
This quality assurance process is not an event, nor a short-term task, nor the verification of a checklist. And why is it necessary to have a procedure for quality assurance of air conditioning projects throughout their useful life?:
Because Murphy's Law is inexorable and also because:
- The needs and requirements of the owner are poorly identified
- Communications were poor and inaccurate
- The work was poorly executed.
i. In the design
ii. During construction
iii. In operation and maintenance
In addition: The owner's goals are not clearly delivered to the design team. This is a very common flaw in our projects. The design team's solution is not clearly delivered to contractors. Which is also very common in our environment and also: The operation and maintenance manuals are not delivered to the owner, which leads to the lack of proper use of the systems, nor are they maintained properly, contributing to their deterioration and non-compliance with the design parameters.
All of the above seems too obvious and / or simple, but there are statistics that confirm that three months after starting a system of those in question, it has lost up to 30% or more of its design conditions, if it has not been operated and maintained properly; with its negative consequences in the fulfillment of the design parameters, in a greater consumption of energy, which in turn, brings a greater impact on the environment.
So if we are all experts in our professions, we are well trained to design, build, operate and maintain our buildings efficiently and effectively, then why so much inefficiency, failures, non-compliance with specifications, excess pollution.
H. Bohanon, PE and DL of ASHRAE, who gave us the first lecture on this topic at ACAIRE says that what happens is that: "There is a high fragmentation between the design, construction and operation of the parts of the 'project team' that leads to duplications, conflicts and inappropriate use of resources."
Quality Assurance is essentially a process that facilitates and guarantees the following aspects, through the different phases and disciplines involved:
- Communication
- Documentation
- Verification,
Thus filling the coordination gaps between civil, mechanical, electrical, hydraulic, data, fire protection engineers, architects and different general contractors. It includes an important group of members, who change from phase to phase. The team must be led by the Quality Assurance Management and the responsibility for the tasks must be clearly and contractually assigned; specific roles and responsibilities vary from phase to phase.
High performance air conditioning
Going into the matter, how is a high-performance air conditioning system achieved? First of all, defining very clearly the RDPs, the bases of the design and executing that design with excellence. It says the RITE in its Article 14. On technical documentation of design and dimensioning of thermal installations.
"Thermal installations falling within the scope of the RITE must be implemented on the basis of technical documentation which, depending on their importance, must adopt the following modality: When the nominal thermal input to be installed in heat or cold generation is greater than 70 kW (20 TR), the realization of a Design Project will be required (see Article 15)".
This design must be oriented towards achieving maximum efficiency and obtaining optimal energy savings. The procedures and approaches are multiple depending on the baseline from where it is initiated and the goal that is intended. If I do it on obsolete, oversized and uncontrolled systems, it will surely be very easy to achieve this, for example by incorporating control and changing the low-performance equipment. But if it is a new design, the considerations are different, first of all it must be consciously designed to achieve maximum efficiency. It is said easy, but it is not so easy.
First of all it must be understood very clearly what energy efficiency is and how it is achieved. It should be remembered that air conditioning systems are highly disaggregated and that there are multiple and very diverse approaches and technologies, in order to obtain the design parameters, requested for each project.
There is a new concept of ASHRAE, which is the bEQ (Building Energy Quiotient), which promotes energy efficiency in buildings and becomes a tool for energy management, modeling, measurement, benchmarking, comparison and evaluation of performance and rational use of energy, making it visible and quantifiable.
It promotes the value of energy efficiency up to the possibilities of the technology available to date. One of its main supports is the ASHRAE Standard 100 – 2015 on Energy Efficiency in Existing Buildings and the energy audits carried out in buildings, before and after starting a program to increase energy efficiency.
It is a great change in the approach to the design of air conditioning projects, which forces us to think about where that energy comes from and its cost: thermal, hydraulic or alternative energy plants placed on the project site; the power and cooling cycles used and their thermodynamic performances, the associated environmental emissions and the impact on climate change. It is a major change that we can measure energy consumption, and compare how buildings were designed and their actual behavior already built and in operation, taking into account their climatic environment, construction materials and occupation.
The bEQ is the quotient of how the actual consumption of the building versus the projected energy consumption is in the design and creates a more holistic approach to energy performance, helping customers make better decisions in the design of their projects and in the specification of high-performance equipment and accessories. There is an intuitive and simple bEQ scale that can range from values below zero for buildings with positive net energy production, to values as high as some greater than 115 (dimensionless) where the building is energy inefficient or greater than 145 which defines it as totally unsatisfactory. The average values of this quotient are on the order of 100 and the optimal values in values less than 25. A real-state information system is required to make the most urgent and necessary choices and changes to optimize energy efficiency.
Note: The second part of this article will be found soon on our website or you can also see it in the printed edition 5 of this publication corresponding to the months of July / August.
* Camilo Botero is the current Secretary of the Federation of Ibero-American Associations of Air Conditioning and Refrigeration - FAIAR; he was president of ACAIRE and is 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. ([email protected]).
