Principles of Design with Climate Lecture #5 Indoor Environment Quality PDF

Prince Mohammad bin Fahd University College of Architecture and Design Department of Interior Design ARCH2341 Principles of Design with Climate Fall 2024/2025 Lecture #5 Indoor Environment Quality IEQ Instructor: Lujain Khalid Al-Eidi The s...

Prince Mohammad bin Fahd University College of Architecture and Design Department of Interior Design ARCH2341 Principles of Design with Climate Fall 2024/2025 Lecture #5 Indoor Environment Quality IEQ Instructor: Lujain Khalid Al-Eidi The sick building The sick building syndrome (SBS) is used to describe a situation in which the occupants of a building experience acute health- or comfort-related negative effects that seem to be linked directly to the time spent in the building. To reduce the sickness and improve the work performance for the building; We should focus on enhancing: Indoor Environment Quality Indoor Environment Quality IEQ Improving the indoor environment quality at buildings will generally enhance: Health well-being. Comfort Productivity. This can be achieved through the implementation of passive design principles, high indoor environment quality, air quality, acoustics, thermal comfort and comfortable lighting. This will also lead to energy savings due to reducing energy demands for heating, cooling and artificial lighting. Indoor Environment Quality IEQ Main Factors Air quality – does indoor air contain sufficient levels of oxygen and acceptable levels of pollutants from internal or external sources? Ventilation – can the room be sufficiently ventilated (preferably naturally but where this is impractical, mechanically) and provide occupants with quality fresh air? Noise – is the room sufficiently insulated from external noise sources and does it minimize internal reverberation and noise levels? Materials – do the chosen building materials and finishes have low levels of Volatile Organic Compounds (VOC) and other hazardous components? Occupant control – are occupants able to control their environment, e.g. through the opening and closing of windows and blinds and operating heating and cooling services? Thermal comfort – is the room sufficiently insulated, shaded and conditioned to ensure comfortable temperatures throughout the year? Light – does the room receive enough daylight throughout the day and is comfortable artificial lighting provided for all other times? External views – does the room allow for distant views that provide a connection to the external environment? Indoor Environment Quality IEQ Balancing Indoor Environment Qualities Designing for a high indoor environment quality can be challenging as all criteria need to be addressed while some may even contradict each other. For instance: Windows and finishes. Windows in particular need to be carefully designed - they influence access to daylight and ventilation, create heat gains in summer and losses in winter and provide a visual and acoustic connection to our immediate environment. Internal finishes not only impact internal sound quality but also influence a room’s thermal comfort, light reflectivity and air quality. Indoor Air Quality IAQ There are two major approaches to reach IAQ issues in buildings: 1. Increase the ventilation rate of outdoor air into the building, 1. Minimize or control the sources of air pollution within and outside the building.  Ventilation Ventilation could be done via Natural and Mechanical ways. The most effective ventilation is achieved through natural cross ventilation. The ideal layout features openable windows located in opposite walls, which creates a breeze path to let in fresh air and flush out stale air. Noise Excessive noise generated by neighbors, traffic and hard surfaces that reflect internal sounds (echo) can impact occupant’s amenity and employee’s productivity. In order to ensure comfortable noise levels, architect should consider inserting Porous absorbers: Common porous absorbers include carpet, draperies, spray-applied cellulose, aerated plaster, fibrous mineral wool and glass fiber, open-cell foam, and felted or cast porous ceiling tile acoustic insulation to internal and external walls also include: double glazing to windows, landscaping that buffers traffic noise and a good balance of internal hard and soft finishes. Noise Natural noise barriers Noise could also be reduced greatly through natural barriers such as white noise. In addition landscaping methods are commonly used to help absorb all loud noises and raucous sounds: A combination of plant forms, primarily evergreen, with broad leaves and foliage near the ground. When also combined with grass or groundcover which will further muffle noise. Also: Evergreen Trees. Tall Hedges. Plants of different Sizes and Shapes. Privacy Fence. Product choice Many materials used in the fit-out and construction of homes and commercial buildings contain Volatile Organic Compounds (VOC) which pose serious health risks to building occupants. VOC’s are found in many common construction materials however alternative low / no VOC products are available on the market including: paints, coatings, sealants, carpets and press wood products (e.g. cabinetry and furniture). Thermal comfort Thermal Comfort Definition Human thermal comfort Thermal Comfort in Buildings Buildings provide environments where people can feel comfortable and safe. To understand the ways building systems are designed to meet these needs; we must first look at how the human body perceives and reacts to interior environments. The American Society of Heating, Refrigerating and Air-Conditioning Engineers. Thermal Comfort Definition “That condition of mind which expresses satisfaction with the thermal environment”. The absence of any discomfort. Thermal balance Thermal Comfort Definition In simple terms, thermal comfort describes the comfortable condition in which a person does not feel too hot or too cold. Why is Thermal Comfort in Buildings Important?  Human thermal comfort Eliminating potential health hazards is a very important aspect of maintaining ideal thermal comfort. Feeling comfortable in an interior space directly impacts people’s mood. In office buildings, working in optimal conditions enables us to think and work better, thermal comfort contributes not only to wellbeing but even to productivity. Saving energy. As architects and interior designers; our goal of spaces is, to create environments where people are neither too hot nor too cold to function comfortably and efficiently. Humans Thermal Comfort Human thermal comfort Thermal comfort varies from one person to another person in the same environmental space, It is a very personal experience according to age, gender, clothing, activity, cultural habits, etc. While conditions required for thermal comfort vary from person to the other, the comfort zone should be the goal of the thermal design of a building, because it defines those conditions that 80% of people find comfortable. According ASHRAE research: Building occupants in typical Winter clothing prefer indoor temperatures between 20°C and 24°C (68°F–74°F). When dressed in Summer clothes, they prefer 23°C to 26°C (73°F– 79°F) temperatures. Human thermal comfort Comfort zone The psychrometric chart Thermal comfort describes the Temperature and Humidity range in which humans feel comfortable. This range can fluctuate by many degrees and percentages, depending on activity levels, clothing, annual seasons and personal preferences. Cold and humid The human body temperature is about 37.°C. Cold and Dry Humans are comfortable only within a very narrow range of conditions. What Influences Thermal Comfort in Buildings? 1. Personal factors 2. Environmental (measurable) factors Environmental factors a) Air temperature This is the temperature of the air surrounding the body, usually given in degrees Celsius (°C). b) Radiant temperature This is the heat that radiates from a warm object. Examples of radiant heat sources include the sun, ovens, dryers, hot surfaces, etc.. c) Air velocity This describes the speed of air movement d) Humidity When heated, water evaporates into the surrounding environment, thereby creating humidity. Personal factors a) Clothing insulation Thermal comfort is very much dependent on the insulating effect of clothing on the wearer..  Personal Factors b) Work rate/Metabolic heat Humans body generates heat even while at rest. The amount of heat our bodies produce depends on what we are doing (Activity Level). Metabolic rate: The speed at which our bodies generate heat. The complex physical and chemical processes involved in the maintenance of life are called the metabolism. We vary individually in the amount of heat we produce and retain in our bodies. The more physical work we do, the more heat we produce.  Personal Factors b) Work rate/Metabolic heat BTU: British Thermal Units We must lose heat at the same rate it is produced and gain heat at the same rate it is lost.  Personal Factors b) Work rate/Metabolic heat Body Heat types Heat Gains: Metabolism. Thermal Comfort in Buildings Absorption. Heat conduction toward body. Heat loss through: Evaporation Conduction: Convention: Radiation:  Personal Factors b) Work rate/Metabolic heat Work rate/Metabolic heat Energy released by metabolism depends on muscular activity. Thermal Comfort in Buildings Metabolism is measured in Met (1 Met=58.15 W/m2 body surface). Body surface for normal adult is 1.7 m2. A sitting person in thermal comfort will have a heat loss of 100 W. Average activity level for the last hour should be used when evaluating metabolic rate, due to body's heat capacity. We can control our thermal comfort by: 1. Becoming more active or less active, which has the effect of speeding up or slowing down our metabolism, Thermal Comfort in Buildings 2. Wearing lighter or heavier clothing, 3. Moving to a warmer or cooler place, or by consuming warm or cold foods. How do Buildings Support Thermal Comfort? Engineers refer to Heating, Ventilating, and Air Conditioning systems and equipment with the acronym HVAC. Thermal Comfort in Buildings  We use the heating and cooling systems Thermal Comfort in Buildings of buildings to control how much heat our bodies give off. Typically, heating systems do not directly raise body temperature, but instead adjust the thermal characteristics of the indoor space to reduce the rate at which our bodies lose heat.