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National Energy Efficiency Programme Audits. Presented by Mohammad A. Al-Muaigel 996714 20/10/2004. King Fahd University of Petroleum and Minerals Mechanical Engineering Department. Outline. The Company Overview. Case Study. Conclusion. What is NEEP? Location
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National Energy Efficiency Programme Audits Presented by Mohammad A. Al-Muaigel 996714 20/10/2004 King Fahd University of Petroleum and MineralsMechanical Engineering Department
Outline • The Company Overview. • Case Study. • Conclusion.
What is NEEP? • Location • Teams working with NEEP • Awareness Team • Auditing Team
Case Study Quick Energy Audit in the Tower Building at Aramco
Building Description • The tower building of Aramco is an administrative building which exists inside Aramco campus in Dhahran. • The building consists of ten floors and a basement with a total floor area of 38,982 square meter. • The building went into operation in 1978. • The average occupancy of the building during working days is 1633 employee. • In addition to the work areas the building includes spaces for machine rooms, restaurants and storages. • The regular operating hours are from 6 am to 4 pm, however some employee may extend their work till 10 pm. • The building consists of two wings the north and the south wings both are symmetrical.
South Wing North Wing Building Layout Fresh air intake, Main Exhaust fan and Elevator machines Upper Podium AHUs Rooms AHUs Room Basement Chillers room and Storage area Building Plan
Electric Power Supply to the Building • The building is supplied by electric energy through two medium voltage feeders of 13.8 kV • The building has six step-down transformers of capacity 2000 kVA each • Two of the step-down transformers are 13.8/2.4 kV, while the other four transformers are 13.8/.480 kV. • The two medium voltage transformers are primarily feeding the cooling chillers. • Two UPS systems are available for the computer center. Each system consists of two modules of a capacity 160 kVA each. • Two standby generators type CAT 3518 suitable for continuous operation of capacity 1450 kW each are available. • The generators are equipped with automatic startup as well as parallel operation with load management facilities. • The two generators are interfacing with the electric system through six ATS, one for each transformer.
HVAC System • The building relies on water/air system for air conditioning, which consists of water chillers and air handling units. • The chillers are water cooled type. The cooling water is provided through a three cells cooling tower which exists behind the building • The chillers station consists of: • Three identical chillers of capacity 450 TR each using R134a • One chiller of capacity 600 TR using R11, usually in operation • Two identical chillers of capacity 200 TR each. These chillers are used for emergency conditions to provide air conditioning to the computer center. • In addition to the chillers plant the building is also receiving chilled water from a nearby central plant. • The main criterion for operating the chillers is to keep the outgoing chilled water temperature at 42 F regardless the outdoor temperature.
HVAC System (contd.) • The building has 78 AHU of capacities ranging from 10 to 50 TR. • Out of these AHUs twenty rely on the external supply of the chilled water. • Twenty five AHUs are dedicated to provide cooling to the computer center. • In addition to the AHUs there is five fan-coils as well as small split AC units of a capacity 2 TR each. • Each floor is served by 4 AHUs two for each wing. • Fresh air of 10% is used during summer. This percentage becomes 20% during the winter season. • Mixing between the fresh and the retuned air is achieved in the room at which the AHU exists. • Fresh air is provided by two central fan which exist in the podium at the top of the building, one for each wing. • Central exhaust fan exist in the podium at the top of the building. • Each Floor has four main working areas, two per wing. The dedicated AHU for this area has a temperature controller installed in the main working area served by this AHU.
Lighting System • The lighting system of the building has been renovated through replacing the 40 W lamps with 32 lamps as well as the electro-magnetic ballast with electronic ballasts. • The lighting system is on timer which enable lighting at 6 am and disable lighting by 10 pm. • The lighting system does not distinguish between the working days and the weekends. • The reception of the building is lit by mercury lamps. Also lobbies in front of the elevators are let by incandescent spot light lamps.
Findings • There is no billing system for the building where the buildings within Aramco campus pay their electricity cost as a pre-determined share of the total consumption. • Although the building is well maintained and equipped with meters however there are no records available for energy consumption in the building or any of its sections • The drawn current of the building is 140 Amp at 13.8 kV. This represents a demand of 2844 kW providing the power factor is 0.85. • The HVAC system keeps the building temperature at 23 C even after the end of working hours. • There is no load management system for the chillers, where three chillers (2*450 + 1*600 TR) are continuously in operation regardless their loading. The average loading of the 2*450 TR and 600 TR chillers are 56%, 57% and 50% respectively. • No hot water system exists in the building. • The building is well insulated and has double glass windows
Energy Conservation Opportunities • Apply scheduling for the operation of HVAC system. • Modify lighting scheduling • Apply a load management for the chiller units • Replacement the incandescent and mercury lamps with high efficiency lamps • Use occupancy (motion) sensors in the rooms • Use exhaust stream of the HVAC system to pre-cool the fresh air stream
Apply scheduling for the operation of HVAC system. • This application rely on the building thermal inertia during off working hours • It includes stopping the air handling units in non critical areas from 10 pm to 5 am the second day and consequently relying on one chiller only during this reduced load hours. • During weekends this scenario will be applied from 5 pm to 5 am the second day. • This application will also combined optimum start application where HVAC system will be started at 5 am.
Modify Lighting Schedule • This application aims at reducing lighting level during late working hours and weekends by 50%. • Employee working during off regular working hours can rely on task lighting in addition to of general lighting • This application may require wiring to have the general lighting on two levels
Apply a load management for the chiller units Case Study for Chiller #1 (450 TR) • This application aims at improving the loading of the chillers to their best efficiency point (i.e. 75%). • This could be implemented using a PLC load management system which takes out unnecessary chiller to improve loading • Implementing this to all chillers will generate an annual savings of 82,254 SR. • The expected system cost is 20,000 US$, this makes the simple pay back period 0.9 year (1 US$ =3.75 SR)
Replacement the incandescent and mercury lamps with High efficiency Lamps Replacement of Mercury Lamp with MHL • Mercury lamps can be replaced with metal halide lamps • Incandescent spot light lamps exist in the elevators lobby can be replaced with CFL lamps. This will improve the light level • Survey of the number of both lamps is needed to define the necessary investment cost Replacement of Incandescent Lamp with CFL
Use exhaust stream of the HVAC system to pre-cool the fresh air stream • This application aims at recover energy from the exhaust stream to pre-cool the fresh air stream through a heat exchanger. • The system cost is 3000 US$ and the installation is about 2000 US$ • The simple pay back period of this application will be 6.4 years
Use Occupancy Sensors • This application include use motion (occupancy) sensors in offices as well as rarely unattended areas such as machine room. • To have reasonable estimate for the impact of this application number of rooms as well as their light load should be surveyed.
