Hygrothermal Performance of Enclosures in a Storage Room and Energy Efficiency in Environmental Control

Figures & data

Figure 1. Enclosure sample and associated structure of its fabric.

Figure 2. Methodological framework.

Figure 3. Diagram of HAM transfer between room and enclosure.

Table 1. Material properties.

Property	Value	Property	Value
Density	6.62 × 10^2 kg/m^3	Heat capacity at constant pressure	1.032 × 10^−3 kJ/(kg.K)
Thermal conductivity	0.055 W/(m·K)	EMC	$[\mathrm{EMC}=(0.01547-0.0006\times T+0.00124\times \mathrm{RH})\times 6.62\times {10}^{-7}]$ kg/m^3
Diffusion coefficient	1.485 × 10^−10 m^2/s	Vapour resistance factors	144.48 (inward)/46.78 (outward)

Table 2. The structure and parameters of the LSTM network.

No. of layer	Name of layer	Parameters	Values
1	Input layer	Input size	2
		Minimum sequence length	1
2 & 3	LSTM layer	Number of neurons	(200, 200)
4	Dropout layer	Probability of dropping out input elements	0.1
5	Fully connected layer	Output size	2
6	Regression layer	Loss function	Mean squared error

Figure 4. Comparison between measured data and simulated data in micro-environment.

Table 3. The results of relaxing the environment.

		This study	Standard
Macro	Band	33–65% RH	40–60% RH
	24 h fluctuation	±16% RH	±10% RH
Micro	Band	43–57% RH
	24 h fluctuation	±9% RH (98% of time: <±5% RH; 2% of time: ±5–9% RH)

Table 4. Performance results of the LSTM network.

	R^2	RMSE	MSE	MAE	SD
Training data (temperature)	0.9974	0.006237	3.88E-05	0.0014	0.0409
Training data (RH)	0.9304	0.003087	9.53E-06	0.04	0.6765
Testing data (temperature)	0.9812	0.002136	4.56E-06	0.0062	0.0186
Testing data (RH)	0.9074	0.002675	7.15E-06	0.1518	0.7435

Table 5. Daily energy consumption in tight and relaxed control.

Seasons	Spring	Summer	Autumn	Winter
Hourly ambient fluctuations	≤±2°C and ±21% RH	≤±2 °C and ±16% RH	≤±3 °C and ±17% RH	≤±4 °C and ±8% RH
Tight control, SC, (±0.5 °C,±3% RH), [kWh]	109.5	36.9	34	174.4
Relaxed control 1 (±2 °C,±10% RH), [kWh]	91.3	30.3	28.6	142.2
Energy saving (percentage decrease compared to the SC), [kWh]	18.2 (16.6%)	6.6 (17.8%)	5.4 (15.9%)	32.2 (18.5%)
Gradient of energy saving potential, [kWh/°C for T, kWh/% RH for RH]	12.1 (T)/2.6 (RH)	4.4 (T)/0.9 (RH)	3.6 (T)/0.8 (RH)	21.5 (T)/4.6 (RH)
Relaxed control 2 (±3°C,±16% RH), [kWh]	89.1	28.9	28.2	141.4
Energy saving (percentage decrease compared to the SC), [kWh]	20.4 (18.6%)	7.0 (18.9%)	5.8 (17.1%)	33.0 (18.6%)
Gradient of energy saving potential, [kWh/°C for T, kWh/% RH for RH]	8.2 (T)/1.6 (RH)	2.8 (T)/0.5 (RH)	2.3 (T)/0.4 (RH)	13.2 (T)/2.5 (RH)

Note: (1) Hourly ambient fluctuations are the differences between maximum and minimum in any 1 h period. Because of building envelopes, associated indoor fluctuations are smaller than the ambient ones. (2) Gradient of energy saving potential is defined as the following equation, $\mathrm{Gradient}={\displaystyle \frac{\mathrm{Energy}\mathrm{saving}}{(\mathrm{Control}\mathrm{accurac}{\mathrm{y}}_{\mathrm{relaxed}\mathrm{control}}-\mathrm{Control}\mathrm{accurac}{\mathrm{y}}_{\mathrm{strigent}\mathrm{control}})}}$.