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CENTRALISED BUILDINGS CONTROL SYSTEMS FOR ENERGY MANAGEMENT
C E N T R A L I S E D B U I L D I N G S C O N T R O L S Y S T E M S FOR E N E R G Y
MANAGEMENT
P. D . P o u l i s Architectural Association Graduate School, iO-11 PERCY London Wl, England
St.
ABSTRACT P u b l i c and p r i v a t e b u i l d i n g s are c o n s t r u c t e d in such a w a y that t h e y i n c l u d e a great v a r i e t y of t e c h n i c a l u t i l i t y a n d s e r v i c e s y s t e m s . T h e n a t u r e of t h e s e s y s t e m s v a r i e s in t h e sense that t h e y a r e r e s p o n s i b l e f o r o p e r a t i o n s r a n g i n g from a i r - c o n d i t i o n i n g to lighting. B e c a u s e of t h e i n c r e a s i n g cost of e n e r g y and l a b o u r , c e n t r a l i s e d been introduced, to c o n t r o l t h e a b o v e b u i l d i n g f u n c t i o n s .
control systems
have
A c e n t r a l b u i l d i n g c o n t r o l system o p e r a t e s by u s i n g s i g n a l s from s e n s o r s d i s t r i b u t e d in t h e e n e r g y c o n s u m i n g a r e a s . T h e s t a t e of h a r d w a r e of t h e s e n s o r s , d e t e r m i n e s the r e a c t i o n s of t h e c e n t r a l c o n t r o l l e r e i t h e r a s t i m e - d e p e n d a n t f u n c t i o n s or a s o v e r riding operations. Optimum o p e r a t i o n of t h e b u i l d i n g system can r e d u c e energy c o n s u m p t i o n by a s m u c h a s t h i r t y p e r c e n t . F u n c t i o n s i n c l u d e a u t o m a t i c t i m e - s c h e d u l i n g of all l i g h t i n g l o a d s , m a n u a l f o r i n d i v i d u a l l o a d s , a i r - c o n d i t i o n i n g and h e a t i n g s c h e d u l i n g .
override
This paper will r e v i e w some of t h e s e c e n t r a l e n e r g y s y s t e m s , from t h e energy m a n a g e r ' s point of v i e w and attempt to g i v e s o m e u s e f u l i d e a s to a r c h i t e c t s and e n g i n e e r s of h o w t o save e n e r g y in b u i l d i n g s , b y u s i n g m i c r o p r o c e s s o r t e c h n o l o g y .
KEYWORDS Centralised energy management; future trends.
technical
specifications;
acceptance;
INTRODUCTION R i s i n g energy c o s t s in r e c e n t y e a r s , c o m b i n e d w i t h t h e d r a m a t i c r e d u c t i o n of c o s t s in c o m p u t e r h a r d w a r e , h a v e c r e a t e d a n e w f i e l d in e n e r g y m a n a g e m e n t in g e n e r a l and in b u i l d i n g s in p a r t i c u l a r . C e n t r a l i s e d c o m p u t e r c o n t r o l s y s t e m s f o r optimum energy u t i l i s a t i o n in b u i l d i n g s , is a m a j o r b r e a k t h r o u g h h e l p i n g the s t r u g g l e f o r l o w e r energy c o s t s and b e t t e r e n e r g y m a n a g e m e n t .
807
808 As domestic and commercial buildings are continually equipped with more comprehensive utility systems, the need for optimum control of these systems is becoming more apparent, as the existing electromechanical control systems of the past are becoming more and more inadequate. Moreover the complexity of the new building utilities, which serve the perpetual thirst for more comfort , makes operation, maintenance and monitoring increasingly difficult. Comparison of the cost of these utilities, to the total cost of the building, shows ne that they account for more than 5 0 % °f t total investment. As a result, and to achieve high availability and utilisation factors, continuous monitoring is required, which minimises the dangers of unexpected breakdowns and low efficiency. These increasingly complex functions cannot be undertaken by the operating staff alone. That is where the need for centralised control systems arises.
SYSTEMS DESCRIPTION The whole system comprises of a central microcomputer, an interface, a storage medium (disc, cassette etc.), the power supply, the visual display unit (V.D.U.) and the printer and the local controllers. The microcomputer is where all the inputs are analysed and according to the software provided by the company to suit the needs of the customer, commands are outputted, to compensate for any unwanted changes sensored by the local controllers. The interface translates the signals coming from the controllers (plant items), to computer language and is software controlled. Whereever there is a need for data recording, a storage medium is used. Such operation is very useful for future reference and statistics as it shows the optimisation provided by the system. The power supply unit provides the internal voltage required by the system. can include a battery back-up system in case of power failure.
This
The V.D.U. enables the minute-to-minute checking of all components of the plant. The printer provides a hard-copy of all operations. The controllers are measuring devices which obtain information optically, acoustically and with registration units either automatically or by keyboard commands. There can be direct and/or analog input control, from the controllers, which interface with the central computer.
SYSTEMS ON THE MARKET There are various systems on the market, ranging from small systems for domestic applications, to large systems with thousands of input/output channels. Most of them are in a modular form, which allows flexibility of operations and also makes expansion easy in order to cover for future loads. Some of the companies producing microcomputer energy management systems are: MEMS (micro energy management system) GEC (measurements) AEG - Telefunken IEM (invicta Energy Management Ltd.) MEM (electronics) Johnson Control Systems Transmitton
809 AEGON (Automated Energy Conservation Ltd.) Holec Energy Simplex - G E Ltd. Systemation Ltd. E n e r g y M a n a g e m e n t and C o n t r o l S y s t e m s L t d . Most of the c o m p e t i n g s y s t e m s a r e v e r y similar, a n d d i f f e r e n c e s exist m a i n l y in d a t a space and p r o c e s s i n g p o w e r . S u c h m i c r o - s y s t e m s can cost from to d e p e n d i n g on t h e size of t h e b u i l d i n g , t h e u t i l i t i e s p r o v i d e d and plant size, c o m p l e x i t y of s o f t w a r e , p e r i p h e r a l s and so on. There are also systems which i n c o r p o r a t e m o r e t h a n one m i c r o c o m p u t e r f o r t h e c o n t r o l of the same b u i l d i n g . The u s e of d i s t r i b u t e d c o m p u t e r s , f o r e n e r g y m a n a g e m e n t , p r o v i d e s some a d v a n t a g e s over the c e n t r a l i s e d s y s t e m s but t h e fact that l o c a l c o m p u t e r s h a v e to c o m m u n i c a t e among themselves anyway, might present problems.
£1,000
£100,000
By u s i n g such c o m p u t e r i s e d s y s t e m s , r e c e n t e x p e r i e n c e h a s shown that energy s a v i n g s of u p to 30% can be a c h i e v e d , in a d d i t i o n to l o w e r m a i n t e n a n c e e x p e n s e s (including a smaller p a y r o l l ) . A system i n s t a l l e d at B r i t i s h A e r o s p a c e at B r o u g h , E n g l a n d by T r a n s m i t t o n , h a s saved t h e c o m p a n y about 7% of t h e t o t a l h e a v y oil f u e l b i l l a n d it is expected to h a v e a p a y b a c k p e r i o d of one y e a r . The computer continually m o n i t o r s and r e c o r d s t h e t e m p e r a t u r e s v i a 21 s e n s o r s a n d 5 o u t s t a t i o n s , and o p t i m i s e s t h e u s e of h e a t and h e n c e t h e u s e of o i l . B e f o r e t h e start of t h e shift, h e a t i n g is switched on, at t h e latest t i m e p o s s i b l e , t o r e a c h t h e r e q u i r e d -temperature. W h e n the t e m p e r a t u r e i s r e a c h e d , t h e h e a t i n g fan is s w i t c h e d o f f . When all t h e a r e a s s u p p l i e d by t h e same p i p e l i n e a r e s w i t c h e d off, t h e n t h e c o m p u t e r i n s t r u c t s the b o i l e r m a n to c l o s e t h e m a i n v a l v e of t h e p i p e l i n e . At the end of the shift, the c o m p u t e r s w i t c h e s off t h e system at t h e e a r l i e s t p o s s i b l e t i m e . A n o t h e r system i n s t a l l e d at t h e V a u x h a l l c r o s s o f f i c e s , E n g l a n d , by D e l t a ( E l e c t r o n i c s D i v i s i o n ) , p r o v i d e s c o n s i d e r a b l e e n e r g y c o n t r o l , and in a s s o c i a t i o n w i t h l o w - e n e r g y c o n s u m p t i o n l a m p s and i n d i v i d u a l c o n t r o l s f o r a i r - c o n d i t i o n i n g and h e a t i n g , p r o d u c e s r u n n i n g and m a i n t e n a n c e c o s t s o f a r o u n d 60 p e n c e p e r square foot per year, for the s q u a r e foot b u i l d i n g .
^-8,000
T h e c o m p u t e r system used, c o n t r o l s m a x i m u m d e m a n d , by load shedding, i.e. s w i t c h i n g off s t a i r c a s e h e a t e r s , c u t t i n g l i g h t i n g to h a l f l e v e l and so on u n t i l t h e o v e r a l l d e m a n d is r e d u c e d to below t h e o v e r l o a d l e v e l . T h e r e a r e m a n u a l l y operated s w i t c h e s f o r o v e r t i m e , w h i c h o p e r a t e f o r one h o u r at a t i m e .
THE
FUTURE
A l l e n e r g y c o n s e r v a t i o n s c h e m e s , to a c h i e v e t h e i r p u r p o s e , h a v e t o be c l e a r l y a c c e p t e d at t h e t o p and enjoy employee p a r t i c i p a t i o n . Computerised energy systems h a v e an a d d e d p r o b l e m . T h e fact that c o m p u t e r s a r e s u p p o s e d to b e looked u p o n a s a t h r e a t to jobs of e n e r g y - m a n a g e r ^ and e n g i n e e r s . F o r t u n a t e l y c o m p u t e r i s e d energy m a n a g e m e n t s y s t e m s a r e but one of t h e t o o l s a v a i l a b l e to t h e e n e r g y e n g i n e e r s . T h i s is b e c a u s e the c u r r e n t c o m p u t e r t e c h n o l o g y c a n n o t p r o v i d e t h e d e c i s i o n m a k i n g of t h e e n e r g y e n g i n e e r , who is to c h o o s e a m o n g s y s t e m s and select t h e one m o s t suited to h i s n e e d s , and it c e r t a i n l y d o e s not p r o v i d e the a b i l i t y to p e r s u a d e t o p m a n a g e m e n t and e m p l o y e e s of t h e n e e d of e n e r g y c o n s e r v a t i o n . C o m p u t e r i s e d s y s t e m s can be o p e r a t e d w i t h o u t s p e c i a l i s e d s k i l l s . S o f t w a r e is p r o v i d e d by the c o n s u l t i n g h o u s e or even by t h e c o m p u t e r c o m p a n y in t h e form of s t a n d a r d p a c k a g e s , w h i c h can be a l t e r e d to suit i n d i v i d u a l n e e d s . E x p a n s i o n of a g i v e n system is u s u a l l y easy a s s y s t e m s c o m e in m o d u l a r form. Payback periods r a n g e from six m o n t h s to t h r e e y e a r s . R e c e n t s t a t i s t i c s show that t h e b u i l d i n g c o n t r o l s m a r k e t is p r e d i c t e d to i n c r e a s e by 76% b y t h e y e a r 1988, and to r e a c h
810 1
$662,000,000. The largest market sector for building control systems will continue to be office building with an estimated 26% share in 1 9 8 8 , up from Z^fo in I 9 8 I . A 16% share for medical buildings will remain constant. Systems in special purpose buildings will increase their share from 1 5 to 1 7 % . The largest advance of all will come in educational buildings, with an increase from 16% to 19%. Retrofittings will become a booming market, as controls of the Fifties and and Sixties are ageing, and produce high energy costs. The future is projected to be very promising for centralised computer energy management systems, and it has to be, as the era of cheap energy is gone for good.
^ Building Control Systems Markets in Europe REFERENCES Payne, G. A. ( 1 9 7 9 ) · The Energy Manager's Handbook. IPC Science and Technology Press. Dubin and Loud ( 1 9 7 8 ) . Energy Conservation Standards. McGraw Hill. Energy Manager (January 1 9 8 3 ) . Energy Manager (March I 9 8 3 ) . Energy Manager (October 1 9 8 2 ) . Energy World (various issues). Technical Brochures supplied by the manufacturers.
MANAGEMENT
P. D . P o u l i s Architectural Association Graduate School, iO-11 PERCY London Wl, England
St.
ABSTRACT P u b l i c and p r i v a t e b u i l d i n g s are c o n s t r u c t e d in such a w a y that t h e y i n c l u d e a great v a r i e t y of t e c h n i c a l u t i l i t y a n d s e r v i c e s y s t e m s . T h e n a t u r e of t h e s e s y s t e m s v a r i e s in t h e sense that t h e y a r e r e s p o n s i b l e f o r o p e r a t i o n s r a n g i n g from a i r - c o n d i t i o n i n g to lighting. B e c a u s e of t h e i n c r e a s i n g cost of e n e r g y and l a b o u r , c e n t r a l i s e d been introduced, to c o n t r o l t h e a b o v e b u i l d i n g f u n c t i o n s .
control systems
have
A c e n t r a l b u i l d i n g c o n t r o l system o p e r a t e s by u s i n g s i g n a l s from s e n s o r s d i s t r i b u t e d in t h e e n e r g y c o n s u m i n g a r e a s . T h e s t a t e of h a r d w a r e of t h e s e n s o r s , d e t e r m i n e s the r e a c t i o n s of t h e c e n t r a l c o n t r o l l e r e i t h e r a s t i m e - d e p e n d a n t f u n c t i o n s or a s o v e r riding operations. Optimum o p e r a t i o n of t h e b u i l d i n g system can r e d u c e energy c o n s u m p t i o n by a s m u c h a s t h i r t y p e r c e n t . F u n c t i o n s i n c l u d e a u t o m a t i c t i m e - s c h e d u l i n g of all l i g h t i n g l o a d s , m a n u a l f o r i n d i v i d u a l l o a d s , a i r - c o n d i t i o n i n g and h e a t i n g s c h e d u l i n g .
override
This paper will r e v i e w some of t h e s e c e n t r a l e n e r g y s y s t e m s , from t h e energy m a n a g e r ' s point of v i e w and attempt to g i v e s o m e u s e f u l i d e a s to a r c h i t e c t s and e n g i n e e r s of h o w t o save e n e r g y in b u i l d i n g s , b y u s i n g m i c r o p r o c e s s o r t e c h n o l o g y .
KEYWORDS Centralised energy management; future trends.
technical
specifications;
acceptance;
INTRODUCTION R i s i n g energy c o s t s in r e c e n t y e a r s , c o m b i n e d w i t h t h e d r a m a t i c r e d u c t i o n of c o s t s in c o m p u t e r h a r d w a r e , h a v e c r e a t e d a n e w f i e l d in e n e r g y m a n a g e m e n t in g e n e r a l and in b u i l d i n g s in p a r t i c u l a r . C e n t r a l i s e d c o m p u t e r c o n t r o l s y s t e m s f o r optimum energy u t i l i s a t i o n in b u i l d i n g s , is a m a j o r b r e a k t h r o u g h h e l p i n g the s t r u g g l e f o r l o w e r energy c o s t s and b e t t e r e n e r g y m a n a g e m e n t .
807
808 As domestic and commercial buildings are continually equipped with more comprehensive utility systems, the need for optimum control of these systems is becoming more apparent, as the existing electromechanical control systems of the past are becoming more and more inadequate. Moreover the complexity of the new building utilities, which serve the perpetual thirst for more comfort , makes operation, maintenance and monitoring increasingly difficult. Comparison of the cost of these utilities, to the total cost of the building, shows ne that they account for more than 5 0 % °f t total investment. As a result, and to achieve high availability and utilisation factors, continuous monitoring is required, which minimises the dangers of unexpected breakdowns and low efficiency. These increasingly complex functions cannot be undertaken by the operating staff alone. That is where the need for centralised control systems arises.
SYSTEMS DESCRIPTION The whole system comprises of a central microcomputer, an interface, a storage medium (disc, cassette etc.), the power supply, the visual display unit (V.D.U.) and the printer and the local controllers. The microcomputer is where all the inputs are analysed and according to the software provided by the company to suit the needs of the customer, commands are outputted, to compensate for any unwanted changes sensored by the local controllers. The interface translates the signals coming from the controllers (plant items), to computer language and is software controlled. Whereever there is a need for data recording, a storage medium is used. Such operation is very useful for future reference and statistics as it shows the optimisation provided by the system. The power supply unit provides the internal voltage required by the system. can include a battery back-up system in case of power failure.
This
The V.D.U. enables the minute-to-minute checking of all components of the plant. The printer provides a hard-copy of all operations. The controllers are measuring devices which obtain information optically, acoustically and with registration units either automatically or by keyboard commands. There can be direct and/or analog input control, from the controllers, which interface with the central computer.
SYSTEMS ON THE MARKET There are various systems on the market, ranging from small systems for domestic applications, to large systems with thousands of input/output channels. Most of them are in a modular form, which allows flexibility of operations and also makes expansion easy in order to cover for future loads. Some of the companies producing microcomputer energy management systems are: MEMS (micro energy management system) GEC (measurements) AEG - Telefunken IEM (invicta Energy Management Ltd.) MEM (electronics) Johnson Control Systems Transmitton
809 AEGON (Automated Energy Conservation Ltd.) Holec Energy Simplex - G E Ltd. Systemation Ltd. E n e r g y M a n a g e m e n t and C o n t r o l S y s t e m s L t d . Most of the c o m p e t i n g s y s t e m s a r e v e r y similar, a n d d i f f e r e n c e s exist m a i n l y in d a t a space and p r o c e s s i n g p o w e r . S u c h m i c r o - s y s t e m s can cost from to d e p e n d i n g on t h e size of t h e b u i l d i n g , t h e u t i l i t i e s p r o v i d e d and plant size, c o m p l e x i t y of s o f t w a r e , p e r i p h e r a l s and so on. There are also systems which i n c o r p o r a t e m o r e t h a n one m i c r o c o m p u t e r f o r t h e c o n t r o l of the same b u i l d i n g . The u s e of d i s t r i b u t e d c o m p u t e r s , f o r e n e r g y m a n a g e m e n t , p r o v i d e s some a d v a n t a g e s over the c e n t r a l i s e d s y s t e m s but t h e fact that l o c a l c o m p u t e r s h a v e to c o m m u n i c a t e among themselves anyway, might present problems.
£1,000
£100,000
By u s i n g such c o m p u t e r i s e d s y s t e m s , r e c e n t e x p e r i e n c e h a s shown that energy s a v i n g s of u p to 30% can be a c h i e v e d , in a d d i t i o n to l o w e r m a i n t e n a n c e e x p e n s e s (including a smaller p a y r o l l ) . A system i n s t a l l e d at B r i t i s h A e r o s p a c e at B r o u g h , E n g l a n d by T r a n s m i t t o n , h a s saved t h e c o m p a n y about 7% of t h e t o t a l h e a v y oil f u e l b i l l a n d it is expected to h a v e a p a y b a c k p e r i o d of one y e a r . The computer continually m o n i t o r s and r e c o r d s t h e t e m p e r a t u r e s v i a 21 s e n s o r s a n d 5 o u t s t a t i o n s , and o p t i m i s e s t h e u s e of h e a t and h e n c e t h e u s e of o i l . B e f o r e t h e start of t h e shift, h e a t i n g is switched on, at t h e latest t i m e p o s s i b l e , t o r e a c h t h e r e q u i r e d -temperature. W h e n the t e m p e r a t u r e i s r e a c h e d , t h e h e a t i n g fan is s w i t c h e d o f f . When all t h e a r e a s s u p p l i e d by t h e same p i p e l i n e a r e s w i t c h e d off, t h e n t h e c o m p u t e r i n s t r u c t s the b o i l e r m a n to c l o s e t h e m a i n v a l v e of t h e p i p e l i n e . At the end of the shift, the c o m p u t e r s w i t c h e s off t h e system at t h e e a r l i e s t p o s s i b l e t i m e . A n o t h e r system i n s t a l l e d at t h e V a u x h a l l c r o s s o f f i c e s , E n g l a n d , by D e l t a ( E l e c t r o n i c s D i v i s i o n ) , p r o v i d e s c o n s i d e r a b l e e n e r g y c o n t r o l , and in a s s o c i a t i o n w i t h l o w - e n e r g y c o n s u m p t i o n l a m p s and i n d i v i d u a l c o n t r o l s f o r a i r - c o n d i t i o n i n g and h e a t i n g , p r o d u c e s r u n n i n g and m a i n t e n a n c e c o s t s o f a r o u n d 60 p e n c e p e r square foot per year, for the s q u a r e foot b u i l d i n g .
^-8,000
T h e c o m p u t e r system used, c o n t r o l s m a x i m u m d e m a n d , by load shedding, i.e. s w i t c h i n g off s t a i r c a s e h e a t e r s , c u t t i n g l i g h t i n g to h a l f l e v e l and so on u n t i l t h e o v e r a l l d e m a n d is r e d u c e d to below t h e o v e r l o a d l e v e l . T h e r e a r e m a n u a l l y operated s w i t c h e s f o r o v e r t i m e , w h i c h o p e r a t e f o r one h o u r at a t i m e .
THE
FUTURE
A l l e n e r g y c o n s e r v a t i o n s c h e m e s , to a c h i e v e t h e i r p u r p o s e , h a v e t o be c l e a r l y a c c e p t e d at t h e t o p and enjoy employee p a r t i c i p a t i o n . Computerised energy systems h a v e an a d d e d p r o b l e m . T h e fact that c o m p u t e r s a r e s u p p o s e d to b e looked u p o n a s a t h r e a t to jobs of e n e r g y - m a n a g e r ^ and e n g i n e e r s . F o r t u n a t e l y c o m p u t e r i s e d energy m a n a g e m e n t s y s t e m s a r e but one of t h e t o o l s a v a i l a b l e to t h e e n e r g y e n g i n e e r s . T h i s is b e c a u s e the c u r r e n t c o m p u t e r t e c h n o l o g y c a n n o t p r o v i d e t h e d e c i s i o n m a k i n g of t h e e n e r g y e n g i n e e r , who is to c h o o s e a m o n g s y s t e m s and select t h e one m o s t suited to h i s n e e d s , and it c e r t a i n l y d o e s not p r o v i d e the a b i l i t y to p e r s u a d e t o p m a n a g e m e n t and e m p l o y e e s of t h e n e e d of e n e r g y c o n s e r v a t i o n . C o m p u t e r i s e d s y s t e m s can be o p e r a t e d w i t h o u t s p e c i a l i s e d s k i l l s . S o f t w a r e is p r o v i d e d by the c o n s u l t i n g h o u s e or even by t h e c o m p u t e r c o m p a n y in t h e form of s t a n d a r d p a c k a g e s , w h i c h can be a l t e r e d to suit i n d i v i d u a l n e e d s . E x p a n s i o n of a g i v e n system is u s u a l l y easy a s s y s t e m s c o m e in m o d u l a r form. Payback periods r a n g e from six m o n t h s to t h r e e y e a r s . R e c e n t s t a t i s t i c s show that t h e b u i l d i n g c o n t r o l s m a r k e t is p r e d i c t e d to i n c r e a s e by 76% b y t h e y e a r 1988, and to r e a c h
810 1
$662,000,000. The largest market sector for building control systems will continue to be office building with an estimated 26% share in 1 9 8 8 , up from Z^fo in I 9 8 I . A 16% share for medical buildings will remain constant. Systems in special purpose buildings will increase their share from 1 5 to 1 7 % . The largest advance of all will come in educational buildings, with an increase from 16% to 19%. Retrofittings will become a booming market, as controls of the Fifties and and Sixties are ageing, and produce high energy costs. The future is projected to be very promising for centralised computer energy management systems, and it has to be, as the era of cheap energy is gone for good.
^ Building Control Systems Markets in Europe REFERENCES Payne, G. A. ( 1 9 7 9 ) · The Energy Manager's Handbook. IPC Science and Technology Press. Dubin and Loud ( 1 9 7 8 ) . Energy Conservation Standards. McGraw Hill. Energy Manager (January 1 9 8 3 ) . Energy Manager (March I 9 8 3 ) . Energy Manager (October 1 9 8 2 ) . Energy World (various issues). Technical Brochures supplied by the manufacturers.