# Sustainable Energy

• Y. H. Venus Lun
• S. L. Dennis Tung
Chapter
Part of the Green Energy and Technology book series (GREEN)

## Abstract

There are many factors to study in designing sustainable heat pump systems. Among them, the loading calculation dictates the system’s equipment selection. Calculating the loading demand for equipment sizing and selecting high-performance system are important in the process to plan for sustainable energy system. When sizing a heat pump, it is essential to determine the required cooling and heating capacity. To begin, this chapter examines factors affecting the heating/cooling demand for indoor thermal comfort. Key variables of thermal comfort are also discussed. To further investigate energy efficiency, coefficient of performance (COP) is examined. There are several methods that exist in determining COP. Equations and methods to determine COP are investigated. Examples of COP calculation on water-to-water heat pump and air-to-water heat pump are illustrated. The findings indicate that the COP level varies with types of heat pumps.

## Keywords

Load calculation Thermal comfort Balance point temperature Heating capacity Cooling capacity Coefficient of performance

## Seasonal energy efficiency ratio

SEER

Seasonal energy efficiency ratio

Q

Reference annual cooling demand

QE

Annual electricity consumption

c

Cooling

h

Heating

## Nomenclature: Fanger’s comfort equation

Ici

Thermal resistance of clothing

M

Rate of metabolic rate production

Pw

Water vapor pressure

tmrt

ta

Air temperature

Va

Relative air velocity

## Nomenclature: Heating and Cooling Capacity

Cp

Specific heat at constant pressure, expressed in joules per kilogram and kelvin

Ebal

Energy balance

Ein

Energy into a system

Eout

Energy out of a system

$$\dot{m}$$

Mass flow rate

QC

Cooling capacity, expressed in watts

QH

Heating capacity, expressed in watts

QHR

Heat recovery capacity, express in watts

q

Volume flow rate, expressed in cubic meters per second

r

Density, expressed in kilograms per cubic meter

t

Difference between inlet and outlet temperatures

## Nomenclature: Coefficient of Performance (COP)

COPC

COP of cooling

COPH

COP of heating

COPHC

COP of heating and cooling

Qcd

Capacity of condenser (for heating)

Qev

Capacity of evaporator (for cooling)

Qhrc

Capacity of heat recovery of condenser (for heating)

Winput

Total input power

h1

Enthalpy in front of the compressor

h2

Enthalpy behind the compressor

h3

Enthalpy at the injection valve

## References

1. 1.
European Commission (2016) Overview of support activities and projects of European Union and energy efficiency and renewable energy in the heating and cooling. European UnionGoogle Scholar
2. 2.
British Standard (BS EN 14522-1) (2013) Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling. BSI Standards PublicationGoogle Scholar
3. 3.
Burdick A (2011) Strategy guideline: accurate heating and cooling load calculations. U.S. Department of Energy (Building Technologies Program)Google Scholar
4. 4.
Robin R (2010) Getting warmer: a field trial of heat pumps. The Energy Saving TrustGoogle Scholar
5. 5.
Li Y, Cheng Z (2003) A balance-point method for assessing the effect of natural ventilation on indoor particle concentrations. Atmos Environ 37:4277–4285
6. 6.
En 14825 (2016) Air conditioners, liquid chilling packages and heat pumps, with electrically driven compressors, for space heating and rating at part load conditions and calculation of seasonal perform. British StandardGoogle Scholar
7. 7.
ANSI/ASHARE Standard 55 (2014) Thermal environment conditions for human occupancyGoogle Scholar
8. 8.
Hensen JLM (1990) Literature review on thermal comfort in transient condition. Build Environ 25(4):309–316
9. 9.
Ekici C (2013) A review of thermal comfort and method of using Fanger’s PMV equation. In: 5th International symposium on measurement, analysis and modelling of human functions. Vancouver, CanadaGoogle Scholar
10. 10.
Fanger PO (1970) Thermal comfort, analysis and application in environmental engineering. Danish Technical Press, CopenhagenGoogle Scholar
11. 11.
Noel D, Rene T, Donatien N (2010) Thermal comfort: a review paper. Renew Sustain Energy Rev 14:2626–2640
12. 12.
Dear RJ (2002) Thermal comfort in naturally ventilated buildings: revisions to ASHARE Standard 55. Energy Build 34(6):549–561
13. 13.
Kwok A, Rakovich NB (2010) Addressing climate change in comfort standards. Build Environ 45:18–22
14. 14.
Mui K, Chan W (2003) Adaptive comfort temperature model of air-conditioned building in Hong Kong. Build Environ 38:837–852
15. 15.
Schiavon S, Melikov AK (2008) Energy saving and improved comfort by increased air movement. Energy Build 40:1954–1960
16. 16.
Cheng CC, Lee D (2016) Enabling smart air conditioning by sensor development: a review. Sensors 16(12):2028.
17. 17.
British Standard (BS EN 14522-3) (2013) Air conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling. BSI Standards PublicationGoogle Scholar
18. 18.
AHRI (550/590) (2015) Standard for performance rating of water-chilling and heat pump water-heating packages using the vapor compressor cycle. Air Conditioning Heating and Refrigeration InstituteGoogle Scholar
19. 19.
ASHARE Handbook (2017) Fundamentals 2.3Google Scholar
20. 20.
Shao S, Shi W, Li X, Ma J (2004) A new inverter heat pump operated all year round with domestic hot water. Energy Convers Manag 45:2255–2268
21. 21.
Shao S, Shi W, Li X, Cheng H (2004) Performance representation of variable-speed compressor for invert air conditioners based on experimental data. Int J Refrig 27(8):805–815
22. 22.
Bonin J (2016) Heat pump planning handbook. Routledge, LondonGoogle Scholar
23. 23.
Zogou O, Stamatelos A (1998) Effect of climatic conditions on the design optimization of heat pump systems for space heating and cooling. Energy Conserv Manage 39(7):609–622