Nomenclature


Figure 18.

Zero and Net Zero Energy

temperature.

28

(a) Interior surface heat flux of north wall, (b) interior surface temperature of north wall, and (c) indoor air


Φ<sup>0</sup> Phase difference between the highest outdoor temperature and the inner surface temperature of wall, deg

HR-EC Harmonic response method and equivalent specific heat capac-

Abbreviations

Author details

Shaanxi, P.R. China

31

CF Carbon fiber

CNTs Carbon nanotubes

Building Envelope with Phase Change Materials DOI: http://dx.doi.org/10.5772/intechopen.85012

NV Night ventilation PCMs Phase change materials

CondFD Conduction finite difference

EPS Expandable polystyrene

DSC Differential scanning calorimeter

ity principle

TSV Thermal storage and ventilation

TSVL Thermal storage and ventilation laboratory

Liu Yang1,2\*, Yan Liu1,2, Yuhao Qiao1,2, Jiang Liu1,2 and Mengyuan Wang1,2

Architecture and Technology, Xi'an, Shaanxi, P.R. China

\*Address all correspondence to: yangliu@xauat.edu.cn

provided the original work is properly cited.

1 State Key Laboratory of Green Building in Western China, Xi'an University of

2 School of Architecture, Xi'an University of Architecture and Technology, Xi'an,

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Building Envelope with Phase Change Materials DOI: http://dx.doi.org/10.5772/intechopen.85012

<sup>c</sup> Specific heat capacity of materials, kJkg–<sup>1</sup>

R Thermal resistance of wall material layer, m<sup>2</sup>

Tex.sur Temperature of the exterior surface, °C

Tin.sur Temperature of the interior surface, °C

Tout Typical outdoor air dry-bulb temperature, °C Trm Mean monthly outdoor air dry-bulb temperature, °C

face temperature, dimensionless <sup>Y</sup>ef Coefficient of heat accumulation of wall outer surface, W<sup>m</sup><sup>2</sup>

°C<sup>1</sup>

<sup>α</sup><sup>e</sup> Exterior surface coefficient of heat transfer, W<sup>m</sup><sup>2</sup>

<sup>α</sup><sup>i</sup> Interior surface coefficient of heat transfer, W<sup>m</sup><sup>2</sup>

ΔT<sup>R</sup> Temperature range during the complete phase change

ΔT<sup>+</sup> Difference between operative temperature and comfort tem-

ξif Delay time between the highest indoor temperature and the inner surface temperature of wall, h ξ<sup>0</sup> Delay time between the highest outdoor temperature and the inner surface temperature of wall, h

Φif Phase difference between the highest indoor temperature and the inner surface temperature of wall, deg

<sup>Δ</sup><sup>h</sup> Latent heat of phase change process, kJkg<sup>1</sup>

<sup>λ</sup> Thermal conductivity of materials, W<sup>m</sup><sup>1</sup>

<sup>λ</sup><sup>p</sup> Thermal conductivity of PCMs, W<sup>m</sup><sup>1</sup>

D Thermal inertia of wall material layer, dimensionless

r<sup>A</sup> Ratio of PCM part area to wallboard area, dimensionless ratio Phase change ratio of PCMs during phase change process, % <sup>S</sup> Coefficient of heat accumulation of wall materials, W<sup>m</sup><sup>2</sup>

Tave Average value of typical outdoor air dry-bulb temperature, °C

Tlim Upper threshold of 80% acceptability limit of Adaptive Comfort

Tmax Maximum value of typical outdoor air dry-bulb temperature, °C Tmin Minimum value of typical outdoor air dry-bulb temperature, °C

vif Damping factor between indoor air and interior surface temperature of building envelope, dimensionless v<sup>0</sup> Damping factor of outdoor air temperature to wall interior sur-

<sup>Y</sup>if Coefficient of heat accumulation of wall inner surface, W<sup>m</sup><sup>2</sup>

Yn,e Coefficient of heat accumulation of the outer surface of material

Model in Standard ASHRAE-55, °C

<sup>c</sup><sup>p</sup> Equivalent specific heat capacity, kJkg–<sup>1</sup>

d Thickness of wall materials, m ITD Intensity of thermal discomfort, °Ch PCT Phase change temperature, °C <sup>q</sup>ex,sur Heat flux of exterior surface, W<sup>m</sup><sup>2</sup> <sup>q</sup>in,sur Heat flux of interior surface, W<sup>m</sup><sup>2</sup>

Zero and Net Zero Energy

Tex.air Exterior air temperature, °C

Tin,air Interior air temperature, °C

Top Operative temperature, °C

layer, W<sup>m</sup><sup>2</sup>

<sup>Δ</sup><sup>H</sup> Latent heat of the PCM, kJkg<sup>1</sup>

process, °C

perature, °C

<sup>ρ</sup> Density of materials, kg<sup>m</sup><sup>3</sup>

ΔT Diurnal temperature difference, °C

Greek letters

30

Z Period of temperature fluctuation, h

ºC–<sup>1</sup>

°C<sup>W</sup><sup>1</sup>

°C<sup>1</sup>

°C<sup>1</sup>

°C<sup>1</sup>

°C<sup>1</sup>

°C<sup>1</sup>

°C<sup>1</sup>

°C<sup>1</sup>

ºC–<sup>1</sup>

