# Achieving Energy Self-Sufficiency in a Dormitory Building: An Experimental Analysis of a PV–AWHP-ERV Integrated System

^{1}

^{2}

^{*}

^{†}

## Abstract

**:**

## 1. Introduction

^{2}solar collector, along with a 58 kW heat pump, for four years. They found that the PV system generated 6% more electrical energy than the heat pump consumed. Additionally, the solar collector produced 20% more heat per unit area than the heat pump powered by the PV system. Shono et al. [23] conducted a time-resolution analysis of BIPV in large-scale commercial buildings, confirming that 33% of their energy demand could be met by PV modules installed on exterior walls and 15% by rooftop modules. Building on this, Perwez et al. [24] assessed the combined impact on the overall decarbonization potential of buildings, including building-integrated photovoltaics (BIPV). Their results indicate that implementing all measures simultaneously could lead to an 84% reduction in annual CO

_{2}emissions. BIPV emerged as a significant contributor, fulfilling 8–16% and 34–63% of the electricity demand when considering threshold constraints and the full utilization of the building surface, respectively. Sigounis et al. [25] investigated the feasibility of achieving zero-energy implementation in library buildings through the integration of BIPV/T, ERV, and AWHP systems. Their analysis revealed that controlling the heat flow with BIPV/T can satisfy the heating demand and reduce energy consumption for ventilation by up to 37%.

_{2}price is increased by about 33 times. Nonetheless, they also indicate limitations to commercialization under the current circumstances.

## 2. Methodology

#### 2.1. Building and System Description

^{2}in May, which is the highest, and 88.69 W/m

^{2}in December, which is the lowest. The building is used as a dormitory, with two people staying in each room, and each person occupies an area of 16.25 m

^{2}.

#### 2.2. Experimental Conditions

#### 2.3. Key Performance Indicators

_{h}and Q

_{c}) of an air-to-water heat pump (AWHP) is determined by Equations (1) and (2), and the coefficient of performance (COP) and energy efficiency ratio (EER) are calculated using Equations (3) and (4).

_{p,w}are mass flow rate of water (kg/s) and specific heat capacity of water (kJ/kg°C). T

_{w,i}and T

_{w,o}are the water temperatures at the inlet and outlet of the condenser (°C).

_{AWHP}is the power usage of the AWHP (kW).

_{saved}) is calculated using Equation (5), and the energy saving efficiency of the ERV is calculated using Equation (6).

_{saved}= η

_{t}× ρ × c

_{p,a}× G × (T

_{OA}− T

_{RA})

_{t}is the efficiency of the ERV. ρ and c

_{p,a}are the density of air (kg/m

^{3}) and specific heat capacity of air (kJ/kg°C). G is the indoor and outdoor ventilation amount per sec (m

^{3}/s). T

_{OA}, T

_{SA}, and T

_{RA}are the outdoor air temperature, supply air temperature, and indoor air temperature (°C), respectively.

#### 2.4. Building Energy Self-Sufficiency Rate

#### 2.5. Economic Analysis

_{AWHP}+ C

_{PV}+ C

_{ESS}

_{AWHP}× P

_{electricity}+ M

_{AWHP}

_{PV}+ E

_{ESS}) × P

_{electricity}

_{AWHP}, C

_{PV}, and C

_{ESS}are the cost of AWHP, PV, and ESS. E

_{AWHP}is the annual energy consumption of the AWHP (kWh). P

_{electricity}is the annual energy consumption per kWh. M

_{AWHP}is the annual maintenance cost of the AWHP.

_{t}is the annual savings in year t, and AOC

_{t}is the annual operating cost in the year t. r and n are the discount rate and number of years.

## 3. Result and Discussion

#### 3.1. Representative Day Analysis

#### 3.1.1. System Performance Analysis

#### 3.1.2. PV Generation and Power Flow Analysis

#### 3.2. Building Energy Independence Analysis

^{2}—were identified as a primary contributing factor to this self-sufficiency. Concurrently, our analysis of the average energy sold to the external grid revealed percentages of 47.78, 36.22, 57.47, 55.94, and 53.22%, underscoring the impact of energy demand imbalances on the energy independence rate. These relationships between the average solar radiation, renewable energy sales ratio, and energy independence rate are visually represented in Figure 7 below.

#### 3.3. Energy Independence Analysis by PV–ESS Capacity

#### 3.4. Economic Analysis of PV–ESS System

## 4. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 8.**Renewable energy rate distribution. (

**a**) Energy self-sufficiency rate for outdoor temperature; (

**b**) Energy self-sufficiency rate based on ratio of power purchase amount to system energy consumption; (

**c**) Energy self-sufficiency rate for difference in power production and energy consumption.

**Figure 9.**Electrical energy flow of integrated energy system. (

**a**) July; (

**b**) August; (

**c**) September; (

**d**) October; (

**e**) November.

**Figure 10.**Annual electricity cost according to PV–ESS capacity. (

**a**) PV capacity changes; (

**b**) ESS capacity changes.

Authors | System Description | Analytical Approach | Evaluation Method | ||
---|---|---|---|---|---|

Performance | Economic | Energy Self- Sufficiency | |||

Long et al. [18] | PVT/ASHP/HST | Simulation | o | x | x |

Kong et al. [19] | PVT/ASHP/HST | Simulation | x | o | x |

Bae et al. [20] | PVT/ASHP/HST | Simulation | o | x | o |

Bae et al. [21] | PVT/ASHP/HST | Experiment | o | o | x |

Aneli et al. [21] | PV/ASHP/HST/EES | Simulation | o | x | o |

Perrella et al. [24] | PV/AWHP/HST/EES | Simulation | x | x | o |

Nicoletti et al. [25] | PV/AWHP | Simulation | o | o | o |

This work | PV/AWHP/ERV/HST /EES | Experiment Simulation | o | o | o |

Component | Specification | |
---|---|---|

AWHP | Model | HM051MR U44 |

Capacity | 5 kW $\times $ 2EA | |

Refrigerant | R32 (1.4 kg) | |

HST | Capacity | 220 L |

ERV | Air volume | 250 CMH |

PV Panel | Capacity | 4.44 kW (370 W $\times $ 12 EA) |

PCS | AC | 5 kW |

Power conversion efficiency | 96% | |

LED | Power consumption | 50 W $\times $ 5 EA13 W $\times $ 5 EA |

Equipment | Metrics | Specification |
---|---|---|

RCN8 Ultrasonic Heat Meter | Heat and flow rate | Accuracy class 2 (European EN1434) Temperature sensor: Pt1000 |

EM415 | Power meter | Accuracy Class B |

SR-05 | Solar radiation | ISO second class pyranometer Uncertainty < 1.8% |

QFA3160 | Temperature and humidity | Accuracy: 0.8 K (15~35 °C) 1 K (−35~50 °C) |

PV Capacity (kW) (%) | |||||||||
---|---|---|---|---|---|---|---|---|---|

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | ||

ESS Capacity (kWh) | 1 | 27.74 | 43.62 | 47.68 | 49.97 | 51.71 | 53.03 | 54.09 | 55.02 |

2 | 27.76 | 48.13 | 53.45 | 55.84 | 57.65 | 58.95 | 60.02 | 60.94 | |

3 | 27.77 | 51.57 | 58.99 | 61.68 | 63.52 | 64.87 | 65.94 | 66.87 | |

4 | 27.79 | 53.81 | 64.00 | 67.43 | 69.36 | 70.76 | 71.86 | 72.79 | |

5 | 27.80 | 55.08 | 68.47 | 73.06 | 75.19 | 76.61 | 77.75 | 78.70 | |

6 | 27.82 | 55.50 | 72.44 | 78.41 | 80.93 | 82.42 | 83.58 | 84.50 | |

7 | 27.84 | 55.56 | 75.78 | 83.28 | 86.28 | 87.66 | 88.65 | 89.44 | |

8 | 27.85 | 55.57 | 78.11 | 86.98 | 90.61 | 91.98 | 92.76 | 93.37 |

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**MDPI and ACS Style**

Yang, S.-K.; Kang, Y.-H.; Ahn, Y.-C.
Achieving Energy Self-Sufficiency in a Dormitory Building: An Experimental Analysis of a PV–AWHP-ERV Integrated System. *Buildings* **2024**, *14*, 882.
https://doi.org/10.3390/buildings14040882

**AMA Style**

Yang S-K, Kang Y-H, Ahn Y-C.
Achieving Energy Self-Sufficiency in a Dormitory Building: An Experimental Analysis of a PV–AWHP-ERV Integrated System. *Buildings*. 2024; 14(4):882.
https://doi.org/10.3390/buildings14040882

**Chicago/Turabian Style**

Yang, Su-Kwang, Yul-Ho Kang, and Young-Chull Ahn.
2024. "Achieving Energy Self-Sufficiency in a Dormitory Building: An Experimental Analysis of a PV–AWHP-ERV Integrated System" *Buildings* 14, no. 4: 882.
https://doi.org/10.3390/buildings14040882