How can ventilation affect human comfort

A Computational Fluid Dynamics CFD code has been used to analyze thermal comfort conditions for a fullscale ventilated room. Unstructured grids have been used to discretize the numerical domain.

Before undertaking a detailed investigation, the code was validated by comparing the numerical results with experimental data available in the literature.

A total of thirteen cases have been modelled to study the effects of inlet air velocity, air temperature, room walls temperature and vent location on the indoor thermal comfort. The study has been extended to cover not only unoccupied rooms but also occupied rooms. For the occupied rooms, different occupant configurations, namely standing person and person sitting on a chair, have been investigated. In these standards, the energy efficiency design of the building envelope was emphasized.

For example, the U -values of external walls, roof and windows are not allowed to be higher than certain values. But ventilation, a potential passive cooling strategy, for each room of a residential building is set to be a fixed value of 1 air change rate per hour ACH in building energy performance simulation, without considering occupants' behavior of opening windows to increase natural ventilation to reduce discomfort and energy consumption.

Thus, in the design stage, architects and engineers often focus on the thermal performance of the building envelope [ 3—5 ] and overlook the energy savings potential of ventilation, which is a significant measure in the reduction of energy consumption of the building and indoor thermal discomfort [ 6 , 7 ]. Therefore, studies on the effect of variable ventilation modes on indoor thermal comfort and energy consumption are of great importance.

Numerous studies have been conducted on the effect of ventilation on building performance. Liping and Hien [ 8 ] studied the impacts of four ventilation strategies and facade designs on the indoor thermal environment for naturally ventilated residential buildings for hot-humid climate according to the number of thermal discomfort hours in a whole typical year on the basis of a series of TAS simulations.

Geros et al. Santamouris et al. Givoni [ 12 ] examined the effectiveness of night ventilation in lowering the maximum indoor daytime temperature. Richard and Gail [ 13 ] reported a new adaptive comfort standard that allows warmer indoor temperatures for naturally ventilated buildings during summer and in warmer climate zones, adopted in ASHRAE Standard Short et al.

Nielsen and Drivsholm [ 14 ] investigated the energy-efficient demand-controlled ventilation in single family houses with the ventilation having two flow rates: a high rate and a low rate. These two mechanical ventilation modes can be switched based on sensing the CO 2 concentration and moisture content in the outdoor air and exhaust air.

A study on ventilation strategy and air change rates in idealized high-rise compact urban areas was conducted by Hang and Li [ 15 ]. They numerically studied the ventilation and air change rates in some aligned square building arrays. However, these studies either focused on some fixed ventilation strategies or on the cooling energy consumption. Although ventilation-related indoor thermal comfort issues have been studied by these authors, these studies are based on different climatic regions.

The situation in the hot summer and cold winter zone in China is different from that of other countries or regions. In addition, compared with developed countries, most residential buildings in China are not houses but apartment buildings, which may rise to 6—20 stories high, with each floor having 4—8 apartments. These two different characteristics lead to a great need for evaluating variable ventilation modes on the improvements of energy requirements and indoor thermal conditions.

This paper uses degree hours [ 17 ] as an index to assess the indoor thermal comfort and gives a detailed analysis of the energy savings potential of variable ventilation, based on a number of building simulations by the program DeST-h. The thermal design for the building envelope of this model, such as the U -values of walls 1.

Energy and indoor thermal comfortable simulations were carried out with the program DeST-h, a dynamic thermal simulation program developed by Tsinghua University in China and validated by comparison with both well-known international thermal simulation programs and experimental results [ 18 , 19 ].

The residential building model was illustrated in Figure 1. The air conditioner has an energy efficiency ratio of 2. The total power density of miscellaneous loads including lighting systems and occupants is 4. To evaluate the energy savings potential and indoor thermal comfort improvement that can be achieved by ventilation, several possible dynamic ACHs in reality were considered, including a fixed ACH of 1 according to the design standards [ 2 ] and variable ACHs of 0.

Hence, in this paper the first two variable ACH modes are considered as natural ventilation, while the latter two mean mechanical ventilation. Although these modes are different, these variable ACH modes are considered to be controlled ideally and thus ventilation can be automatically changed according to the difference of indoor and outdoor temperatures in building simulation, to minimize cooling and heating energy demands. The lower limit value of 0.

Indoor relative humidity and air temperature are two key factors that influence indoor thermal comfort. Figure 2 presents the Hangzhou's monthly average outdoor relative humidity. However, a field survey on the thermal comfort in residential buildings conducted by Li [ 23 ] showed that occupants in this area have adapted to an average indoor relative humidity of as high as In other words, a high indoor relative humidity will not cause an uncomfortable indoor thermal condition in this area.

Therefore, only indoor air temperature was considered to assess the indoor thermal comfort in this paper. Day lighting is a significant factor for pleasant interior conditions. Without sufficient day lighting, people cannot perform well and healthy. Daylighting design strategies like high or clerestory windows, light shelves, and well-placed skylights can help distribute sunlight inside a space.

Both are important in Net Zero Energy Buildings. Light fixtures "Luminaires" are the hardware required to hold and operate artificial light sources The primary concern in lighting layout is to avoid glare on activity surfaces.

Such glare is a result of light bouncing directly into user's eyes, rather than diffusely. The images below demonstrate just two of the many different ways of lighting a simple room to give exactly the same lighting levels on each work surface. Each layout has advantages and disadvantages. For instance, the first layout might use less energy, but the second layout will cause less glare and will have fewer shadows cast on work surfaces by occupants.

Views are the ability for building occupants to see landscape, objects, and people outside the building. For many occupants, the outlooks from their space or public areas are a major factor in their enjoyment of the site and it can add considerably to the ambience of a building. Views are measured by drawing a line of sight from a location in the building to any exterior windows; if the line of sight to an exterior window is unbroken, that location has a view.

The line of sight must be drawn at the appropriate height for occupants; for instance, typical office workers or students are usually sitting, with eye level assumed to be 42" 1. In order to be considered a view, the window must provide a reasonable vantage point outside the building. One rule considers view windows "vision glazing" to be any glazing above 30". Views should not be obstructed by furniture or walls in the room.

While some people may be tall enough to see over obstructions, an average height should be assumed. When designing the external works, emphasis should be put on to create and preserve natural habitats by providing extensive lawns, keep the area is natural state, trees and hedges, green roofs, and green facades.

In some cases which the area of plot is small, rooftop planting can replace ground sealed by construction work. Environment plays an important role in satisfying basic human needs and quality of life.

It can help to reduce stress and also can speed up recovery. In addition, it can affect humans on a psychological and physical level by acting as a recuperative and stimulating factor for our creative functions. In densely developed cities, it is critical for human health to strike a balance between making space accessible to people and preserving flora and fauna.

According to some studies, dealings with nature will affect human's mental health, whereas leisure activities in nature directly benefit to physical health Acoustic Comfort Acoustic comfort means having the right level and quality of noise to use the space as intended. Acoustic comfort is especially important for schools and office buildings. We can optimize room shape and size to reduce echoes and reverberation.

And you can use acoustic tiles on ceilings and walls to dampen the sound. Straight surfaces reflect sounds back into the central space making sound clarity muddy. Different materials absorb sound frequencies differently. Make sure your acoustical treatments are absorbing the right sound frequencies. Be aware that sounds traveling within 30 milliseconds of each other are perceived without echo.

Sounds traveling after the 30 millisecond threshold become echoes of the original sound. Read Time 4 Minutes. Corey Flynn April 9, Read Time 3 Minutes. Carolina Giavedoni November 30, Read Time 7 Minutes. Cookie Policy SimScale uses cookies to improve your user experience. Accept Data Privacy. Privacy Overview This website uses cookies so that we can provide you with the best user experience possible. Strictly Necessary Cookies Strictly Necessary Cookie should be enabled at all times so that we can save your preferences for cookie settings.

Enable or Disable Cookies. Enable All Save Settings. Spaces where ventilation requirements are primarily associated with building elements, not occupants. Spaces where occupants are engaged in higher levels of activity, but not strenuous, or activities generating more contaminants. Spaces where occupants are engaged in a more strenuous activity, but not exercise, or activities generating more contaminants.