*Evaluation of Well-Being and Thermal Comfort of the LAD-MA Construction System for Low… DOI: http://dx.doi.org/10.5772/intechopen.98699*




**Table of comparison. Current Chilean Building regulation for thermal insulation standards and Minimum thermal insulation standards complying with the Sustainable Housing Certification**

*Source: Own elaboration based on Art. 4.1.10 of the O.G.U.C and the Sustainable Housing Construction Standards, volume II, Energy [6].*

#### **Table 1.**

*Comparative table of thermal transmittance standards for ventilated roofs, walls, and floors.*

#### **2.3 Thermal Comfort**

Considering thermal comfort as one of the main variables in building design, standards such as ISO 7730 and ASHRAE 55 have been developed. These Standards are used as a reference to determine the performance of buildings, through measurement tools. In the case of Chile, the ASHRAE standard has been used as a reference for the design of the housing energy-rating tool [8].

#### *2.3.1 Standard UNE-EN ISO 7730: 2006*

The purpose of the standard is to predict the thermal sensation and the degree of discomfort within a built environment, by calculating a Predicted Mean Vote (PMV) and an Estimated Percentage of Dissatisfied (PPD), taking into account levels of clothing and metabolic activity of people, as well as wind speed, turbulence percentage, among other parameters.

The PMV is an index that reflects an average of votes cast by a large group of people concerning a 7-level thermal sensation scale, which is expressed in **Table 2**.

The PMV index can be estimated for different combinations of metabolic rate, clothing insulation, air temperature, mean radiant temperature, relative air

*Evaluation of Well-Being and Thermal Comfort of the LAD-MA Construction System for Low… DOI: http://dx.doi.org/10.5772/intechopen.98699*

velocity, and air humidity; for the effect of the purpose of the standard, the following simplified expression is used:

$$PMV = aT + bPv - c$$

Where *T* is the ambient temperature in [°C] and *Pv* the pressure of the water vapour in the environment in [kPa].

The constants a, b and c are constants that relate the physical quantities of temperature and pressure to obtain the PMV which is a dimensionless variable and these are obtained from the following table, depending on the time of exposure to the indoor environment and depending on the gender of the subject (**Table 3**).

On the other hand, the PPD index is determined based on the PMV expressed in the following equation:

$$\text{PPD} = \mathbf{100} - \mathbf{95e} - \left( \mathbf{0.3353PMV^4} + \mathbf{0.2179PMV^2} \right)$$

*2.3.2 ASHRAE 55*

This standard determines the influence of environmental variables on human comfort. Although these variables are the same used in the ISO 7730, the difference is that ASHRAE 55 seeks to determine the comfort temperature ranges and then determine the PMV-PPD values, thus deriving in two ways of determining the thermal comfort based on De Dear's studies.

The ASHRAE Standard provides two approaches to thermal comfort on buildings. The first approach focuses on buildings with centralized HVAC systems,


#### **Table 2.**

*Scale of 7 levels verbalized according to thermal sensation, PMV (UNE-EN ISO 7730: 2006).*


#### **Table 3.**

*Values of constants a, b and c to be used in the PMV estimation equation.*

#### **Figure 4.**

*Thermal Comfort Range for Santiago, Chile, based on ASHRAE 55 Standard. Source: own elaboration using climatic data from Santiago (855740 WMO Station Number) plotted on the Psychrometric Chart provided by the software Climate Consultant.*

considering an airspeed of 0.2 [*m*/*s*], a sedentary metabolic activity between 1 [*met*] and 1.3 [*met*], and the option of insulation of clothing varies between 0.5 [*clo*] and 1.0 [*clo*], similar to that described above, corresponding to summer and winter respectively. Based on the Fanger thermal balance, a hygrothermal comfort range illustrated in **Figure 4** is determined.

The second method focuses on buildings without centralized HVAC systems, and determines a dynamic comfort temperature based on the average ambient temperature outside the buildings, this continues to maintain a requirement that there be a sedentary metabolic activity between 1 [met] and 1.3 [met], and that people can vary the clothing insulation between 0.5 [*clo*] and 1.0 [*clo*]. However this method is valid only if the outside temperature oscillates between 10 [°*C*] and 33.5 [°*C*], and that their measurements are greater than 7 days and a maximum of 30 days, thus generating the minimum and maximum comfort temperature equations.

$$\text{Tmín}, \ m\text{á} \propto 0.31 \cdot T \text{Ex} t + 17.80 \pm 3.50$$

Regarding humidity, the standard establishes a maximum humidity radius of 0.012, equivalent to the vapor pressure of 1.910 [kPa], and does not determine a minimum. Also, consider an acceptability index of 80%.
