*2.1.2 The role of thermal comfort*

major opportunity for reducing the total global energy consumption and greenhouse gas emissions. Naturally ventilated building designs using devices such as wind catchers and solar chimneys are progressively being used for increasing fresh air flow and reducing energy consumption in buildings. Proper natural ventilation is of necessity owing to the high cost of maintenance of mechanical ventilation systems and relative increase in electrical energy cost needed to operate such machine. It is therefore justified to apply wind and solar energy, which are renewable energy sources, to provide adequate thermal comfort, indoor air quality and solve some

According to Awbi [16] ventilation is the "Replacement of polluted or stale indoor air by fresh or unpolluted air from outside." The main purpose of a ventilation system, mechanical or natural, in a building is providing acceptable thermal environment and indoor air quality for its inhabitants. In summary, ventilation in a

1.Deliver adequate air for breathing and removing CO2. The conventional level for the maximum concentration of CO2 within an occupied space is 5000 parts per million, or 0.5% by volume for an exposure of 8 h as recommended in

Ventilation systems are designed and incorporated in buildings to provide comfortable microclimates in the ventilated spaces [16]. The microclimate in this circumstance includes a thermal environment and air quality [21]. Therefore, in the design of natural ventilation systems these two factors (providing acceptable air

The human body's thermal balance are considered to be affected by four environmental factors (air temperature, mean radiant temperature, air velocity and

**Activity 0.1% CO2 0.25% CO2 0.5% CO2** At rest 5.7 1.8 0.085 Light work 8.6–18.5 2.7–5.9 1.3–2.8 Moderate work 5.9–9.1 2.8–4.2 Heavy work 9.1–11.8 4.2–5.5 Very heavy work 11.8–14.5 5.5–6.8

**Minimum ventilation required (litre/s per person)**

2.Eliminate huge quantity of contaminants and airborne toxins.

3.Cool the building and its occupants in hot seasons [16–20].

quality and thermal comfort environment) are considered.

*Ventilation rates required to limit CO2 concentrations [18].*

challenges associated with mechanical ventilation systems.

*Zero-Energy Buildings - New Approaches and Technologies*

**2. Literature review**

building is designed to;

**Table 1**.

**Table 1.**

**80**

*2.1.1 Ventilation and thermal comfort*

**2.1 Ventilation**

There are some several reasons why thermal comfort is important in the design of buildings. These are:

