Informe de entrevistas realizadas a los directivos de las instituciones

(a) Time-Scheduled Operation: This technique consists of starting and stopping of the systems based on the time and type of day. Type of the day refers to weekday, weekends and any other days that has a different schedule of operation. This is the simplest technique in function to maintain and operate.

(b) Optimization of Start/Stop: M echanical system installed in buildings are not required 24 hrs therefore they should be shut down during un occupancy and restarted prior to occupancy in order to cool down or heat up depending upon the requirements on a fixed schedule. This feature has the capability to automatically start and stop the system to minimize energy required to maintain the desired environmental conditions during occupied hours. This technique was devised to achieve higher energy efficiency for reducing building utility costs by decreasing the time duration for the operation of the HVAC system supply fan (Gondhalekar, 2013). Theoretically, without sacrificing thermal comfort, a delay in start-up and an early shut down of the equipment can also potentially increase energy efficiency. The thermal capacity of the building mass allows for reduction in supply fan operation, therefore it is expected that more massive buildings have higher potential for getting benefit from this technique.

Start/stop optimization program can monitor outdoor and indoor temperatures and keeps the equipment on at optimized time to conserve energy (Gondhalekar, 2013). Stop time

102 optimization is often incorporated to shut down the equipment before the occupants leave but not so early that the building becomes uncomfortable before the unoccupied mode of operation.

(c) Advanced Thermostat Settings: One way to conserve electrical energy in the building is to reduce the cooling requirement of each zone. Advanced thermostat can be programmed and has the facility to set desired room temperatures for different periods of the day and for different days of the week. They offer better settings than ON-OFF timers or manual shutdown.

These types of thermostats can be programmed for the entire week within the range of 5°C or higher offset condition during the period of no occupancy to save energy in the building.

(d) Demand Control: It helps in the reduction of electrical load which will add to setup peak electrical demand. There can be numerous ways to reduce electrical load. The most commonly used method is by continuously monitoring and predicting the electrical load, when these predictions exceed the preset limits certain scheduled electrical loads are shut off to reduce the rate of consumption and predicted peak demand. To reduce the peak demand the loads are turned off on priority basis, so that the initial load drop action can be achieved efficiently.

(e) Outside Air Economizer: Using outside air economizer cycle can be a good energy efficiency technique. It utilizes the outside air to satisfy all or portion of requirement for building cooling. The outside air is introduced into the building through the mechanical system during the cooling cycle in replacement for the recirculation air.

(f) Use of Single Water Pump: It is found that during the non occupancy period of the building in summer season, the building cooling demand can be met comfortably with the help of a single chiller. By making use of single water pump with a higher chilled water temperature setting to 8°C can be used satisfactorily. Operation of the system with one chilled water pump can reduce the motor power around 7KW. There are additional advantages, such as reduction

103 in pumping heat and improved chiller performance, due to the increased temperature of leaving chilled water.

(g) Chilled Water Reset: The energy generating chilled water in a reciprocating or centrifugal electric driven machines are predisposed by different constraints including the temperature of chilled water leaving the system. When chilled water temperature was selected at peak design times, under absence of effective humidity control, this temperature could be elevated during operating hours, in-order to satisfy the greatest cooling requirement.

(h) Condenser Water Temperature Reset: The other parameter which affects the energy consumption through air-conditioning system is the temperature of condenser water entering the machine. In application heat rejection system is designed to produce a precise condenser water temperature at peak wet bulb temperature. Optimization of system can be attained by resetting the temperature to its initial value by which the outdoor wet bulb temperature produces a lower condenser water temperature.

(i) Night Purge: The night purge technique was designed to reduce energy thermal energy requirement. During the unoccupied periods air conditioning is not required. For that period outdoor air is supplied into the building to cool the building for reduce the cooling load at the beginning of the occupancy. Fundamentals for applying this energy efficiency measure, the controller is required to monitor and control the outdoor and indoor air-temperatures as well as the supply fan. When the controller applies Night Purse the outdoor air schedule should allow the outdoor air damper to open fully.

The controller should activate the main supply fan when the outdoor air reaches a set temperature to blow outdoor air inside the building. The supply air continues until the outdor air temperature falls to a predefined temperature (Ascione, 2016).Thugh the night purse can be

104 used fr this study, but its possible to rojecy in anther context for regulating this operation in warm & humid climate where the relative humidity may not exceed a specified value.