This page contains a Flash digital edition of a book.
HOLISTIC


GAINS A


Electrical building services engineers can help cut CO2 emissions, energy use and costs by applying a ‘whole-life total ownership cost’ approach, write Tony Sung, Ya Ping Du, Marty Barrett and Laurie Brady


1 x 2 x3 DNO-2 11KV supply


lthough many buildings use electricity for 24 hours every day of the year, the price of electricity that the building user pays to a


supplier may be different depending on the time the electricity is being used. In some countries, the price of electricity during peak time may be 150% of the price of electricity at off-peak. There is also a difference in the content of CO2 emissions between peak and off-peak periods. Soon it may be possible to apply smart


meters in conjunction with a good energy management system to optimise the energy benefiting from the least expensive tariffs at the time of the demand. In the form of a generalised but simplified form of optimisation equation, this would be to minimise, say, the objective function1 Ξ( )y :


Ξ( )y = f x( , , , ..., ) n x


where y = maximum energy efficiency % of the electrical distribution system


Figure 1: Three-transformer (150% rated) dual primary dual secondary supply DNO-1 11KV supply Subject to:


m number of relationships governed by ≤ inequalities 11 1 12 2 13 3


a x + a x + a x a x p a x + 22 2


...+ 1n 21 1 … m1 1 a x + a 2m x2 + a 3m x amn n m


a x + a x a x p2 x ≤ p


23 3...+ 2n 3...+


n ≤ 1 n ≤


r number of relationships governed by ≥ inequalities


b x +b x b x b x q b x +b x +b x b x q


11 1 12 2 13 3...+ 1n 21 1 22 2 23 3...+ 2n


+ … b x +b x b x b x pr r1 1 r2 2 + r3 3...+ rn n ≤


s number of relationships governed by = equalities


c x + c x + c x c x e 21 1 22 2 23 3...+ 2nxn = e2


11 1 12 2 13 3...+ 1n c x + c x + c x c


… c x + c 2s x2 + c x c x e= s s1 1 s3 3...+ sn n


We need to apply some non-negativity restriction, for example, 1


x is the


professional fees of the electrical building services engineer, 2


G1 ( , , , ..., ) 0 x x 2 x3 x ≥ n transformer, 3x is installation cost etc. These x is the size of an HV/LV


variables should not have a negative value: 1


The above generalised equations are G2 400/230V Bus


Connection point for mobile genset


all-encompassing for the whole electrical installation. By breaking it down into smaller manageable chunks, electrical building services engineers can offer a best- value engineered whole-life building carbon and energy ownership system to the client. This article analyses the supply arrangement for a fictitious building to illustrate how to carry out this best-value engineering design exercise using the whole-life total ownership cost (WLTOC) design approach.


48 CIBSE Journal June 2011 www.cibsejournal.com n = 1 n ≤ 1 n ≤ 2


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72