We continue with the second of three parts of this interesting article that talks about how to design, install, operate and maintain high-performance HVAC systems.
by Camilo Botero*
In the previous edition, topics related to high-performance air conditioning, the phases of a project, quality assurance, and the topic of energy efficiency under the concept of bEQ (Building Energy Quiotient) were mentioned, now we will discuss breaking down this last concept and other planning phases of an excellent HVAC design.
There is energy efficiency labeling, which informs about the use of potential and actual energy in a building and also feeds back to the owners and operators of how their building is behaving. It informs owners and buyers of the efficiency with which a particular building performs and projects the long-term costs of energy use.
The bEQ, is a great differentiator that gives great preponderance to buildings with zero or positive energy balance, and highlights high performance buildings; those who are in the average are determined and finally explicit the inefficient or unacceptable, which can be penalized or prevented from operating. It focuses only on documenting and understanding energy, identifying opportunities to improve its performance during operation and also allows comparisons between different buildings that have the same use.
Moving on to another issue, a strategy of very high energy efficiency is constituted by the Thermal Cooling Districts, which are large centralized systems, which produce cold water, which is carried by properly insulated pipe networks, which lead it through a predetermined area, supplying the energy necessary to air condition several buildings at the same time, with very considerable benefits since the simultaneity factor is considerably reduced, thus being able to have centralized systems of much smaller size, in relation to the thermal load installed in the buildings, considerably increasing the efficiency of the systems and minimizing the installed capacities.
Air conditioning optimization
For the optimization of air conditioning, all the novelties that have been incorporated into this industry are used, one of them is the rational use of energy, through control, to achieve that the amount of energy required at partial loads due to air conditioning demand is consumed as precisely as possible.
There are excellent protocols, programs, sensors, valves, actuators, etc., which allow to achieve that coupling between the demand profile of the systems and their energy consumption without deteriorating compliance with the design parameters. I think we could make more effort in this issue of control of systems, encouraging the training of engineers and technicians who know in depth the fundamentals and applications of controls, but who understand what thermal systems are like, since they react in minutes, hours and even days, while the control systems react in fractions of a second. Lack of knowledge of this principle very often results in control systems that do not operate properly.
This implies substantial changes in technology such as designing with all the available technological resources and I will cite only a few: "Free Cooling" of all kinds, Heat Pipe, CDQ, Convert, Superheaters in the Cooling cycle, Cold Beams, Controlled Sunlight Lighting, Underside Supply (UFAD) and Displacement Ventilation, Cooling with Pipe in Walls, Floors and Ceilings; Enthalpic Wheels, Heat Exchangers of All Kinds, Peltier Effect, Cogeneration and Trigeneration with Waste Heat, Direct and Indirect Evaporative Cooling, etc.
This must be accompanied by bold proposals in legislation - standardization, as well as very effective methodologies during the phases of pre-design, design, construction, operation and maintenance of buildings such as commissioning (quality assurance throughout the useful life of the project) and energy audits; but above all a deep awareness of the need and goodness to incorporate this concept into our daily lives.
At the same time, the use of standards, codes and regulations has been promoted and updated in Latin America and specifically in Colombia, such as Resolution 0549, which already requires from 2017, very considerable reductions in energy consumption, which lead to high efficiency systems, care of the environment, compliance with design parameters, especially in issues such as indoor air quality. ASHRAE, in this aspect does a wonderful job writing guides, standards and even some in code language that will then be mandatory. We must learn from this partnership.
In Colombia, the version of RITE 2017 (Regulation of Thermal Installations in Buildings) was developed, which contemplates, our climatic and constructive conditions, as well as the systems of commonly used units, the own terminology; This RITE 2017, was already incorporated as the BPI 09 of ACAIRE (Good Engineering Practice), which is increasingly used, but which does not have the required impact, since it is not yet a mandatory regulation. The day it is finally approved by the state and becomes mandatory, our air conditioning projects will improve considerably, with a great impact on the increase in Energy Efficiency.
Consultants and designers must be engineering professionals with deep knowledge of psychrometry, heat transfer, fluid mechanics, turbomachinery, selection of systems from the existing multiples, in-depth knowledge of the technologies available at the date of design that aim at maximum efficiency and the rational use of energy, with control strategies that accommodate very precisely to partial loads.
Once the project requirements specified by the owner, the basis of the design, a Quality Assurance plan have been elaborated, the following Construction and O&M processes must be continued.
* 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]).
