A PRESENTATION ON ENERGY SAVING IN BASEMENT CAR PARK VENTILATION FOR THE ADMINISTRATIVE BUILDING AT GREAMS ROAD ,CHENNAI.
ADMIN BUILDING AT GREAMS ROAD, CHENNAI • Proposed Hi-Tech Admn. Bldg Consists of 2 Towers- G+8 / G+5 and has a common lower and upper level Basement • Capacity of Basement – Parking for 157 cars & 97 two-wheelers. • Area of Basement (covers Towers 1&2) • Lower Basement 4664 sq.m • Upper Basement 4437 sq.m • Ceiling height of basements - 2.2 Mtr
Car Parking area in Basements are fully enclosed. • Enclosed Under-ground parking area requires Mechanical Ventilation. • In absence of Ventilation, Parking facility presents several Internal Air Quality problems. • Most serious is the emission of high levels of Carbon-Monoxide(CO) • CO is easily absorbed by Haemoglobin in Human Blood and can Inhibit Oxygen delivery to Body and can cause adverse health effects varying from headache to death
The NATIONAL BUILDING CODE OF INDIA – 2005 Specifies the following parameters for Ventilation: CO level- within 29mg/cu.m (25 ppm) with Peak level not to exceed 137 mg/cu.m.(125 ppm) As per ASHRAE Max Level for CO 8 hrs exposure – 25ppm 1 Hour exposure- 35 ppm Air change requirement as per NBC for Basement Car Parking : • 9 to 12 ACPH under normal conditions ( For Design purpose 10 ACPH is used) • 30 ACPH in case of fire emergency
DUCTED VENTILATION • The Conventional Ventilation System is the ducted Ventilation system. This has: -Provision of Fresh air fan and Exhaust Air Fans with ducting arrangement as per requirement. - To be operated based on timing control. - Full capacity of Fans has to be operated irrespective of Smoke level or CO Concentration.
DUCTLESS VENTILATION The Modern method of Ventilation system is the Ductless Ventilation system in which : - No Ducts are required. - Only Fresh Air Fans, Exhaust Air Fans and Jet Fans required. - CFD(Computational Fluid Dynamics) analysis, is utilised to decide the number and location of Jetfans for effective and optimum performance. - A group of approximately 4 Nos of Jet Fans are controlled by one CO Sensor and Integrated with IBMS. - When the CO level exceeds threshold value, CO Sensors extends signal to IBMS and accordingly the corresponding group of Jet Fans are triggered. - When CO level exceeds threshold value in approximately 50% of CO Sensors per Basement , then Fresh Air/ Exhaust Fans are switched ON through IBMS along with jet fans
ADVANTAGES OF DUCTLESS VENTILATION • No ducts: duct system and accessories are eliminated. • Improved air quality and efficient Operation • Optimum use of Car Park Space & Optimisation of Head room for Vehicles and Pedestrians. • Flexibility in installation,quicker installation • Effective smoke management • During Fire Conditions, the volume of air to be handled is of the order of 1.25 lakh CFM. Under this situation ductless system fares better compared to ducted system.
How energy saving is achieved in Ductless Ventilation? • Ducts are associated with pressure drop,hence higher size F.A/E.F. are reqd. • Jetfans are located using CFD Analysis in a manner that they help FA/EF to suck/exhaust air respectively, hence smaller size(HP) FA/EFreqd. • During low traffic in Basement, depending upon CO level concentration, only a group of Jetfans may be switched ON by IBMS to distribute/ dilute CO concentration, while in ducted system higher capacity FA/EF have to be kept ON most of the time.
Construction / Characteristics of a Jet Fan 4 4 2 3 2 3 1 5 5 • 1 - Casing made of Sheet Steel • 2- Special silencers at the inlet and outlet side • 3- Inlet cone(s) • 4- Protection guard(s) • 5- mounting brackets for ceiling suspension • Suitable for 300deg C operation for 1 hour • Speed : 1450 / 2900 rpm – Dual speed • CFM : 1900 / 3800 • KW : 0.3 / 1.5 • Sound level : 53 / 71 dB • Area Served by each Fan – 280 sq.mtr.(Approx)
Comparison between Ducted & Ductless system: • Ducted system Operating Cost : • Assumption : All Fans Operation for 2 Hours (Peak Hour), for Balance 6 Hours (Lean Period) Half an Hour ON & Half an Hour OFF. • So, Total operating time=5 hrs/day. • Total unit consumption assuming 5hrs operation/day • =134.7 KW x 5 hrs = 673.5 KWH/day. • Running cost per annum assuming Rs.7/- per unit rate • = 673.5 x 25 days X 12 months X Rs.7/- • = Rs. 14,14,350/- per annum.
Comparison between Ducted & Ductless system: • Ductless system • Operating cost : • I.Peak 2 hrs - All jet fans, fresh/exhaust fans ON. • a) Jet fans(32X0.3KW) =9.6 KWX2hrs = 19.2 units • b) Fresh air and exhaust fan =77.0 KW X 2hrs = 154.0 units • II. For balance 6 hrs (Fresh air & Exhaust fan OFF) a)25% (2 groups i.e. approx. 8 fans ) jet fans ON for 2 hrs =9.6KWX25%x2hrs = 4.8 units b)12.5% (1 group i.e. approx. 4 fans ) jet fans ON for 2 hrs = 9.6KWX12.5%x2hrs= 2.4 units c) For 2 hours (consisting of 4 durations of ½ hr. each) all Fans are OFF = Nil . . Total units/day = 180.40 units Energy cost/annum = 180.40X 25 days X 12 months X Rs.7/- = Rs. 3,78,840.00 Maintanence Cost for Jet fans p.a = Rs. 75,000.00 Total Operating Cost per annum = Rs. 4,53,840.00
Calculation of Payback period Ducted Ductless 1. Fresh air & Exhaust fans Rs. 50.90 lakhs Rs. 43.43 lakhs 2. Ducting and electrical panel and cabling, cable tray,CO sensors. Rs. 20.00 lakh Rs. 15.00 lakhs 3. Jet fans NIL Rs. 32.00 lakhs Total cost Rs. 70.90 lakhs Rs. 90.43 lakh Capital cost for ducted System Rs. 70.90 lakhs Capital cost for ductless System Rs. 90.43 lakhs Additional capital cost Rs. 19.53 lakhs Savings in Operating cost/ Annum by providing jet fans = Rs. (14,14,350/- - 4,53,840/-) = Rs. 9,60,510/- per annum. Pay back period= 19.53 x 12 months 9.60 = 24.41 months Or Say 24 months