This document discusses integrated CO2 solutions for hotels. It notes that hotels have significant energy consumption for heating, hot water, and cooling. An "all-in-one" CO2 heat pump provides space heating, hot water, and AC cooling using CO2 as the refrigerant. This is a more economical retrofit solution for hotels compared to district heating. Success requires customized systems that consider the specific hotel's demands and flexibility in secondary system design and heat distribution. If implemented in 10% of European hotels, CO2 systems could save over 3.6 TWh of energy and 1.1 million tons of CO2 emissions annually.

2. “All-in-one” CO2
solutions for hotels
Norwegian University of Science and Technology
Silje Marie Smitt

3. Contents
Ø Energy trends in the hotel sector
Ø Integrated CO2 solutions for hotels
Ø Design factors for success
Ø The way forward

4. European hotel sector
150,000
Hotel
6,000,000 +5.2%
$ Hotel
+4%
STR, Horwath HTL , REST

5. Hotels’ energy consumption
STR, Horwath HTL , REST
6% AC cooling
63% Heating
and hot
water
31% Others
Oil
Electric
heating

6. Heating loads in hotels
Scandic Hell Hotel (Norway) consumption 2016
400
350
300
250
200
150
100
50
0
Power[kW]
January December
Typical heat-power consumption for Nordic hotels
Peak power
Average power
Minimum power

7. Hot water consumption
Hot water load [16th October, 2018]
Scandic Hell Hotel (Norway) consumption 2018

8. Why CO2 as a retrofit solution?
• “All-in-one” heat pump solution with CO2 as refrigerant
• Space heating, hot water, AC cooling
+ external/internal defrost, freezer & chiller
• Larger economical savings compared to district heating
• Temperature glide in transcritical operations
• Hotels à Large hot tap water consumption
• Relatively easy to install and cheap as a retrofit solution
compared to ammonia

9. “All-in-one” CO2 systems
100
80
60
40
20
0
-20
T[°C]
Entropy [J/ kg K]
90 barSystem schematic TS – diagram of CO2 heat pump
Schematic of system at Scandic Hell Hotel (Norway)
HT circuit
MT circuit
CO2
gas coolers

10. Layout of secondary hydronic circuits
(Kelvin AS)
Success factors
Ventilation
DHW preheat
Evap. defrost
Radiators
Reduce CO2
temperature
before
expansion
Ø Customized systems -
Demands and availability
Ø Secondary system design
Ø Flexibility
Ø Heat distribution in series
Ø Operation of heat storage

11. Success factors
Ø Storage dimensioning
Ø Series of tanks
Ø Design flexibility
Ø Stratification
Ø Tank design
Ø Charging strategy
Hot water storage (Hafner, 2019)

12. Hot water peak shaving
150 kW
Scandic Hell Hotel (Norway) consumption 2018
Load reduction due to hot water storage buffer

13. How can CO2 change Europe?
CHOSE project estimation 2001: European consumption and
emissions: 39 TWh, 10 Mt CO2. Assumed 4% annual increase.
Ø “All-in-one” CO2 systems in 10 % of European hotels
Ø Potential savings:
3.6 TWh 1.1 Mt
CO2
330,000.

14. The way forward
Ø The hotel sector is growing
- Large potential market
Ø Strict legislation
- Demand for new and environmentally
friendly solutions
Ø Solutions for hotels in warm climates
- CO2 with ejectors, parallel compression

15. Questions
are welcome!
silje.smitt@ntnu.no