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Review article from ASHRAE symposium, San Francisco, January 1986
Review article from ASHRAE Symposium, San Francisco, January 1986 How to save energy in hotel system design
C. E. H e n c k Henry Adams, Inc., PO Box 10657, Baltimore, M D 21204, USA Received 7 M a y 1986
The following papers were presented at this symposium: 1. HVAC systems and energy conservation in hotels by J. R. Wagner, Environmental Engineering Co., Baltimore, Maryland. 2. Cogeneration for resort hotels by T. D. Baker, RTKL Associates, Inc., Baltimore, Maryland. 3. How much sense do room occupancy sensor controls make? by H. P, Becker, Chavenah Keane and Company, New York. This Paper reviews these three articles. (Keywords: energy conservation;hotel system design)
Article de synthhse d'aprbs le symposium de I'ASHRAE, San Francisco, janvier 1986 Comment bconomiser l'6nergie dans la conception d'un syst~me pour h6tel Les rapports suivants ont ktk present~s h c e symposium: 1. Les syst~mes de chau~'lhge, ventilation, conditionnement d'air et les ~conomies d'energie dans les hStels par J. R. Wagner, Environmental Engineering Co., Baltimore, Maryland. 2. Cog~ndration pour les hd)tels de vill~giature par T. D. Baker, R T K L Associates, Inc., Baltimore, Maryland. 3. Port~e de la signification des d~tecteurs d'oeeupation des locaux par H. P. Becker, Chavenah Keane and Company, New York. Cet article passe en rerue ces trois rapports.
(Mots ties: economic d'energie: conception des systemes pour h6tel)
Three papers were presented in this symposium on how to save energy in hotel system design. A short review of each is presented below. The titles of the papers and their authors are given above. HVAC systems and energy conservation The first paper presented during the symposium was by Richard Wagner, on 'HVAC systems and energy conservation in hotels'. This paper discusses the effect that the design of the basic HVAC system has on the relative success of energy conservation efforts in hotels. The unusual nature of a hotel is explained along with the impact that it has on the HVAC system. The paper stresses the practical considerations which must be made Ol4(~7007/86/050273 03$03.00 ' 1986 Buuerworth & Co (Publishers Ltd and IIR
by the HVAC system designer when he designs the guest rooms, public areas, back-of-the-house areas, temperature control system, and energy management system. The advantages of providing separate air handling systems are presented. The benefits of line voltage electric controls for guest room fan coil units are explained, General recommendations for arrangement of ventilation systems and possible opportunities for heat recovery are included. More energy can be conserved by thought put into the design of the basic HVAC systems in a hotel than by specifying a sophisticated energy management system. When a poorly selected p u m p or fan requires a 2 0 H P m o t o r instead of a 10 or 15 H P motor, there is little that the energy management system can do to compensate.
Rev. Int. Froid 1986 Vol 9 Septembre
273
Hotel system design. C. E. Henck When systems lack the flexibility needed to satisfy the unique requirements of hotels, they are expensive to operate. When systems are so complex that they cannot be operated and maintained properly, they are ineffective and waste energy. An effective system combines good energy management principles with good HVAC system design. Designing effective systems for hotels requires a thorough knowledge of hotels and how they operate.
electrical loads for lighting, fan motors, elevators, escalators and receptacle uses. Process heat demands arise from kitchen, servery, banquet, restaurant, laundry and bakery functions. Once the loads requiring service have been quantified and realigned (shifted) to maximize simultaneous demands, the engineering task of cogeneration application becomes one of economics. National legislation is now in place to foster the use of cogenerating central utility plants. Serving utility companies are now by law required to buy back excess energy during periods of reduced hotel demands. Resort hotel loads, converted into electricity and heat demands, are tabulated in terms of savings (positive cash flow) or costs (negative cash flows).
Cogeneration 'Cogeneration for resort hotels' was presented by Timothy Baker. His paper explains that resort hotels should be considered for application of cogeneration to take advantage of higher thermal efficiency and consequent energy cost avoidance. Modern resort hotels require comfort and reliability from mechanical and electrical systems on an around the clock basis. Load profiling reveals simultaneous process heating and electricity use requirements that aid in the selection and sizing of cogeneration equipment. Resort hotel needs include
Controls The third paper was presented by Herbert Becker, P.E. on 'How much sense do room occupancy sensor controls
Table 1
Monthly and annual cash flow (in dollars) for cogeneration system 2 ° Tableau 1 Flux de trbsorerie mensuel et annuel (en dollars) pour le syst~rne de coobneration 2 General data 5000 kw + 30000 Mb h Fuel input required: 66 000 Mbh + m a k e - u p shortfall of 5 0 0 0 0 M b h with natural gas Cost of cogenerator $700 k W - 1 0.05
0.06
0.07
0.08
0. t 0
O. 14
Cost of electricity direct Benefit of heat Cost of fuel Cost of fuel shortfall Monthly P + I Maintenance
+ 180 000 + 108 000 - 237 600 - 36 000 -41000 - 5 000
+ 216 000 + 108 000 - 237 600 - 36 000 -41000 - 5 000
+ 252 000 + 108000 -- 237 600 -36000 - 4 1 000 -5000
+ 288 000 + 108000 - 237 600 --36000 - 4 1 000 -5000
+ 360 000 + 108000 - 237 600 -36000 --4I 000 -5000
+ 504000 + 108 000 -- 237 600 -36000 - 4 1 000 --5000
Monthly cash flow Annual cash flow
- 3 1 600 - 379 200
+4400 + 52 800
+ 40 400 +484800
+ 76 400 +916800
+ 148 400 + 1 780800
+ 292 400 4-3 508800
Average electrical cost ($) 1. 2. 3. 4. 5. 6.
Cost of cogenerator $800 k W - 1 0.05
0.06
0.07
0.08
0.10
0.14
Cost of electricity direct Benefit of heat Cost of fuel Cost of fuel shortfall Monthly P + I Maintenance
+ 180 000 + 108000 - 237 600 -36000 - 46 125 - 5 000
+ 216 000 + 108000 - 237 600 -36000 - 46 125 - 5 000
+ 252 000 + 108000 -- 237 600 --36000 --46 125 -5000
+ 288 000 + 108000 - 237 600 -36000 --46 125 5000
+ 360 000 + 108000 -- 237 600 --36000 --46 125 --5000
+ 504 0(30 + 108000 - 237 600 --36000 - 4 6 125 --5000
Monthly cash flow Annual cash flow
- 3 6 725 - 4 4 0 700
-725 - 8 700
+ 35 275 + 423 300
+ 71 275 + 855 300
+ 143 275 + I 719 300
+ 287 275 + 3 447 300
Average electrical cost ($) 1. 2. 3. 4. 5. 6.
Cost of cogenerator $900 k W Average electrical cost ($) 1. 2. 3. 4. 5. 6.
Cost of electricity direct Benefit of heat Cost of fuel Cost of fuel shortfall Monthly P + I Maintenance Monthly cash flow Annual cash flow
0.05 + 180000 + 108000 - 237 600 - 36 000 - 5 1 250 - 5 000 - 4 1 850 - 502 200
0.06
0.07
0.08
0.10
0.14
+216000 + 108000 - 237 600 - 36 000 - 5 1 250 - 5 000
+252000 + 108000 - 237 600 -36000 - 5 1 250 -5000
+288000 + 108000 - 237 600 -36000 - 5 1 250 -5000
+ 360000 + 108 000 - 237 600 -36000 - 5 1 250 -5000
+504000 + 108 000 - 237 600 -36000 - 5 I 250 -5000
- 5 850 + 70 200
+30150 + 361 800
+ 6 6 150 + 793 800
+ 138 150 + 1 657 800
= D a t a in this table are represented graphically in Figure 1 + , Savings to cogenerator - , Cost to cogenerator
274
Int. J. Refrig. 1986 Vol 9 September
.
.
.
.
.
.
.
.
.
.
- 7
-
-
+ 2 8 2 150 + 3 385800
Hotel system design. C. E. Henck
8070 60 50 40 30 w
20
15-'
toi
4
3! i 4
i
!
i
i
i
i
6
7
8
9
iO
II
l
12
I
i
13
14
CENTS PER KILOWATT HOUR (C/KWH) AVERAGE ELECTRIC|TY COST
Figure I Simple p a y b a c k for c o g e n e r a t i o n system 2, based on initial costs of the c o g e n e r a t i o n system as a function of electrical costs. C o g e n e r a t o r cost: - , $ 7 0 0 k W - 1 ; , $800kW-1; $900 k W - i F i g u r e I Temps de relour simple pour le systi'me de cogeneration 2, d'apri's le cofit d'im:est issement du syst ~me de cogenerat ion en jbnct ion du tout de l'electricit& Cofit du generateur: , $700kW-l: $800kW 1: _ --,$900kW-i
make?' The presentation explained that hotel operators are faced with a confusing array of both remote and local guest room energy control devices. A wide variety of decentralized electronic room controllers, each with its own control logic and vendor claims, are in competition with remote front desk microprocessor controls which are essentially blind to actual occupancy. To add to the quandary, operational philosophies vary markedly. On one extreme the criteria is 'the guest is king of his environment, as long as he has the key to his room'. On the other extreme the dictum is 'energy economy is a major priority, limited only by management's degree of acceptance of guest inconvenience or complaint'. The paper is a review of the characteristics of various controllers, their behaviour with different in-room evironmental equipment, and guest reactions to the potpourri of available devices. Cash flow tabulations are presented for the three systems analysed. The data is presented in tabular and graphical form. The tabular data shows, for these systems, the cogeneration costs for various electrical costs. Table 1 (Table 5 in the original paper) shows these costs for system 2. The graphical data shows the simple payback based on initial costs of the cogeneration system as a function of electrical costs. Figure 1 (Figure 2 in the original paper) shows results for system 2.
Rev. Int. Froid 1986 Vol 9 Septembre
275
C. E. H e n c k Henry Adams, Inc., PO Box 10657, Baltimore, M D 21204, USA Received 7 M a y 1986
The following papers were presented at this symposium: 1. HVAC systems and energy conservation in hotels by J. R. Wagner, Environmental Engineering Co., Baltimore, Maryland. 2. Cogeneration for resort hotels by T. D. Baker, RTKL Associates, Inc., Baltimore, Maryland. 3. How much sense do room occupancy sensor controls make? by H. P, Becker, Chavenah Keane and Company, New York. This Paper reviews these three articles. (Keywords: energy conservation;hotel system design)
Article de synthhse d'aprbs le symposium de I'ASHRAE, San Francisco, janvier 1986 Comment bconomiser l'6nergie dans la conception d'un syst~me pour h6tel Les rapports suivants ont ktk present~s h c e symposium: 1. Les syst~mes de chau~'lhge, ventilation, conditionnement d'air et les ~conomies d'energie dans les hStels par J. R. Wagner, Environmental Engineering Co., Baltimore, Maryland. 2. Cog~ndration pour les hd)tels de vill~giature par T. D. Baker, R T K L Associates, Inc., Baltimore, Maryland. 3. Port~e de la signification des d~tecteurs d'oeeupation des locaux par H. P. Becker, Chavenah Keane and Company, New York. Cet article passe en rerue ces trois rapports.
(Mots ties: economic d'energie: conception des systemes pour h6tel)
Three papers were presented in this symposium on how to save energy in hotel system design. A short review of each is presented below. The titles of the papers and their authors are given above. HVAC systems and energy conservation The first paper presented during the symposium was by Richard Wagner, on 'HVAC systems and energy conservation in hotels'. This paper discusses the effect that the design of the basic HVAC system has on the relative success of energy conservation efforts in hotels. The unusual nature of a hotel is explained along with the impact that it has on the HVAC system. The paper stresses the practical considerations which must be made Ol4(~7007/86/050273 03$03.00 ' 1986 Buuerworth & Co (Publishers Ltd and IIR
by the HVAC system designer when he designs the guest rooms, public areas, back-of-the-house areas, temperature control system, and energy management system. The advantages of providing separate air handling systems are presented. The benefits of line voltage electric controls for guest room fan coil units are explained, General recommendations for arrangement of ventilation systems and possible opportunities for heat recovery are included. More energy can be conserved by thought put into the design of the basic HVAC systems in a hotel than by specifying a sophisticated energy management system. When a poorly selected p u m p or fan requires a 2 0 H P m o t o r instead of a 10 or 15 H P motor, there is little that the energy management system can do to compensate.
Rev. Int. Froid 1986 Vol 9 Septembre
273
Hotel system design. C. E. Henck When systems lack the flexibility needed to satisfy the unique requirements of hotels, they are expensive to operate. When systems are so complex that they cannot be operated and maintained properly, they are ineffective and waste energy. An effective system combines good energy management principles with good HVAC system design. Designing effective systems for hotels requires a thorough knowledge of hotels and how they operate.
electrical loads for lighting, fan motors, elevators, escalators and receptacle uses. Process heat demands arise from kitchen, servery, banquet, restaurant, laundry and bakery functions. Once the loads requiring service have been quantified and realigned (shifted) to maximize simultaneous demands, the engineering task of cogeneration application becomes one of economics. National legislation is now in place to foster the use of cogenerating central utility plants. Serving utility companies are now by law required to buy back excess energy during periods of reduced hotel demands. Resort hotel loads, converted into electricity and heat demands, are tabulated in terms of savings (positive cash flow) or costs (negative cash flows).
Cogeneration 'Cogeneration for resort hotels' was presented by Timothy Baker. His paper explains that resort hotels should be considered for application of cogeneration to take advantage of higher thermal efficiency and consequent energy cost avoidance. Modern resort hotels require comfort and reliability from mechanical and electrical systems on an around the clock basis. Load profiling reveals simultaneous process heating and electricity use requirements that aid in the selection and sizing of cogeneration equipment. Resort hotel needs include
Controls The third paper was presented by Herbert Becker, P.E. on 'How much sense do room occupancy sensor controls
Table 1
Monthly and annual cash flow (in dollars) for cogeneration system 2 ° Tableau 1 Flux de trbsorerie mensuel et annuel (en dollars) pour le syst~rne de coobneration 2 General data 5000 kw + 30000 Mb h Fuel input required: 66 000 Mbh + m a k e - u p shortfall of 5 0 0 0 0 M b h with natural gas Cost of cogenerator $700 k W - 1 0.05
0.06
0.07
0.08
0. t 0
O. 14
Cost of electricity direct Benefit of heat Cost of fuel Cost of fuel shortfall Monthly P + I Maintenance
+ 180 000 + 108 000 - 237 600 - 36 000 -41000 - 5 000
+ 216 000 + 108 000 - 237 600 - 36 000 -41000 - 5 000
+ 252 000 + 108000 -- 237 600 -36000 - 4 1 000 -5000
+ 288 000 + 108000 - 237 600 --36000 - 4 1 000 -5000
+ 360 000 + 108000 - 237 600 -36000 --4I 000 -5000
+ 504000 + 108 000 -- 237 600 -36000 - 4 1 000 --5000
Monthly cash flow Annual cash flow
- 3 1 600 - 379 200
+4400 + 52 800
+ 40 400 +484800
+ 76 400 +916800
+ 148 400 + 1 780800
+ 292 400 4-3 508800
Average electrical cost ($) 1. 2. 3. 4. 5. 6.
Cost of cogenerator $800 k W - 1 0.05
0.06
0.07
0.08
0.10
0.14
Cost of electricity direct Benefit of heat Cost of fuel Cost of fuel shortfall Monthly P + I Maintenance
+ 180 000 + 108000 - 237 600 -36000 - 46 125 - 5 000
+ 216 000 + 108000 - 237 600 -36000 - 46 125 - 5 000
+ 252 000 + 108000 -- 237 600 --36000 --46 125 -5000
+ 288 000 + 108000 - 237 600 -36000 --46 125 5000
+ 360 000 + 108000 -- 237 600 --36000 --46 125 --5000
+ 504 0(30 + 108000 - 237 600 --36000 - 4 6 125 --5000
Monthly cash flow Annual cash flow
- 3 6 725 - 4 4 0 700
-725 - 8 700
+ 35 275 + 423 300
+ 71 275 + 855 300
+ 143 275 + I 719 300
+ 287 275 + 3 447 300
Average electrical cost ($) 1. 2. 3. 4. 5. 6.
Cost of cogenerator $900 k W Average electrical cost ($) 1. 2. 3. 4. 5. 6.
Cost of electricity direct Benefit of heat Cost of fuel Cost of fuel shortfall Monthly P + I Maintenance Monthly cash flow Annual cash flow
0.05 + 180000 + 108000 - 237 600 - 36 000 - 5 1 250 - 5 000 - 4 1 850 - 502 200
0.06
0.07
0.08
0.10
0.14
+216000 + 108000 - 237 600 - 36 000 - 5 1 250 - 5 000
+252000 + 108000 - 237 600 -36000 - 5 1 250 -5000
+288000 + 108000 - 237 600 -36000 - 5 1 250 -5000
+ 360000 + 108 000 - 237 600 -36000 - 5 1 250 -5000
+504000 + 108 000 - 237 600 -36000 - 5 I 250 -5000
- 5 850 + 70 200
+30150 + 361 800
+ 6 6 150 + 793 800
+ 138 150 + 1 657 800
= D a t a in this table are represented graphically in Figure 1 + , Savings to cogenerator - , Cost to cogenerator
274
Int. J. Refrig. 1986 Vol 9 September
.
.
.
.
.
.
.
.
.
.
- 7
-
-
+ 2 8 2 150 + 3 385800
Hotel system design. C. E. Henck
8070 60 50 40 30 w
20
15-'
toi
4
3! i 4
i
!
i
i
i
i
6
7
8
9
iO
II
l
12
I
i
13
14
CENTS PER KILOWATT HOUR (C/KWH) AVERAGE ELECTRIC|TY COST
Figure I Simple p a y b a c k for c o g e n e r a t i o n system 2, based on initial costs of the c o g e n e r a t i o n system as a function of electrical costs. C o g e n e r a t o r cost: - , $ 7 0 0 k W - 1 ; , $800kW-1; $900 k W - i F i g u r e I Temps de relour simple pour le systi'me de cogeneration 2, d'apri's le cofit d'im:est issement du syst ~me de cogenerat ion en jbnct ion du tout de l'electricit& Cofit du generateur: , $700kW-l: $800kW 1: _ --,$900kW-i
make?' The presentation explained that hotel operators are faced with a confusing array of both remote and local guest room energy control devices. A wide variety of decentralized electronic room controllers, each with its own control logic and vendor claims, are in competition with remote front desk microprocessor controls which are essentially blind to actual occupancy. To add to the quandary, operational philosophies vary markedly. On one extreme the criteria is 'the guest is king of his environment, as long as he has the key to his room'. On the other extreme the dictum is 'energy economy is a major priority, limited only by management's degree of acceptance of guest inconvenience or complaint'. The paper is a review of the characteristics of various controllers, their behaviour with different in-room evironmental equipment, and guest reactions to the potpourri of available devices. Cash flow tabulations are presented for the three systems analysed. The data is presented in tabular and graphical form. The tabular data shows, for these systems, the cogeneration costs for various electrical costs. Table 1 (Table 5 in the original paper) shows these costs for system 2. The graphical data shows the simple payback based on initial costs of the cogeneration system as a function of electrical costs. Figure 1 (Figure 2 in the original paper) shows results for system 2.
Rev. Int. Froid 1986 Vol 9 Septembre
275