INTD 3007 Building Technology 2: Mechanical & Safety Systems PDF

INTD 3007 Building Technology 2: Mechanical & Safety Systems Claudina Sula Week 6 "Building" by x-av is licensed under CC BY-NC-SA 2.0....

INTD 3007 Building Technology 2: Mechanical & Safety Systems Claudina Sula Week 6 "Building" by x-av is licensed under CC BY-NC-SA 2.0. 1  BUILDING TECHNOLOGY 2: MECHANICAL & SAFETY SYSTEMS What Thermalis a & Air Quality Comfort building? https://www.parsnord.dk/thermal-comfort-2/ Heating – governed by OBC 2  BUILDING TECHNOLOGY 2: MECHANICAL & SAFETY SYSTEMS What Week 6 - is a Comfort & Air Quality Thermal building? Principles of Thermal Comfort Principles of Heat Transfer in Buildings Humidity Indoor Air Quality (Readings, Binggeli, chapters 12-14) 3 Thermal Comfort What is Thermal Comfort? Thermal Comfort is the provision of and satisfaction with a save and comfortable interior environment for human beings. 4 What is Thermal Comfort? When we are able to give off heat and moisture at a rate that maintains a stable, normal body temperature - we achieve a state of thermal comfort”. Binggeli Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI / ASHRAE Standard 55). The human body can be viewed as a heat engine where food is the input energy. The human body will generate excess heat into the environment, so the body can continue to operate. ASHRAE Standard 55: Specifies conditions where 80% of sedentary or slightly active persons find the environment thermally acceptable. 5 Thermal Comfort Factors - Personal Factors There are several primary factors that directly affect thermal comfort that can be grouped in two categories: personal factors and environmental factors. Personal factors - because they are characteristics of the occupants  Metabolic rate  Clothing  Activity Levels  Age  Gender  Adaptation  Circadian Rhythms  Cultural influences  Stress Level 6 Thermal Comfort Factors - Environmental Factors Environmental factors: are conditions of the thermal environment.  Air Temperature  Temperature of surrounding surfaces  Mean radiant temperature  Humidity levels  Air Movement  Natural ventilation  Non-uniformity of Environment Even if all these factors may vary with time, standards usually refer to a steady state to study thermal comfort, just allowing limited temperature variations. 77  Thermal Comfort Standards Thermal comfort calculations according to ANSI / ASHRAE Standard 55 can be freely performed with the CBE Thermal Comfort Tool for ASHRAE 55. Similar to ASHRAE Standard 55 there are other comfort standards like EN 15251 and the ISO 7730 standard http://comfort.cbe.berkeley.edu/ The Center for the Built Environment (CBE) is a research center at the University of California, Berkeley. CBE's mission is to improve the environmental quality and energy efficiency of buildings by providing timely, unbiased information on building technologies and design techniques. 8 Thermal Comfort Conditions Since there are large variations from person to person in terms Of physiological and psychological satisfaction, it is hard to find an optimal temperature for everyone in a given space. Laboratory and field data have been collected to define conditions that will be found comfortable for a specified percentage of occupants. 99 Bioclimatic Design Design with Climate: Bioclimatic Approach to Architectural Regionalism, by Victor Olgyay-1963. Design with Climate describes an integrated design approach that remains a cornerstone of high performance architecture. Bioclimatic design uses nature’s energies to harmonize buildings with local conditions. The physics of the environment, such as solar radiation and the convection of wind are employed as formal influences to create a climate balanced design. four interlocking circles: Biology Climatology Technology Architecture 10 8 Thermal Comfort - Bioclimatic Index Due to all of differences discussed earlier, it is difficult to address the needs of every person, but as designers, we can address the thermal comfort needs of most people in a space. Bioclimatic diagram is based on the maximum and minimum average registers and minimum and maximum average, of the dry bulb’s temperature and relative humidity, respectively. 11  Thermal Comfort Values We need to design for the average thermal comfort temperatures for most people. As a medical definition, the range generally considered suitable for human occupancy is: 15 °C (59 °F) to 25 °C (77 °F), though human comfort can extend beyond this range depending on humidity, air circulation and other factors. For interior spaces, we usually adapt a range of indoor spaces temperature for cold and hot seasons. These values of thermal comfort are: 20-24 °C (68-75.2 °F) - Winter Clothes 23-26 °C (73.4-78.8°F) - Summer Clothes 12  How to convert Celsius to Fahrenheit How to convert Celsius to Fahrenheit 0 degrees Celsius is equal to 32 degrees Fahrenheit: 0 °C = 32 °F The temperature T in degrees Fahrenheit (°F) is equal to the temperature T in degrees Celsius (°C) times 9/5 plus 32: T(°F) = T(°C) × 9/5 + 32 or T(°F) = T(°C) × 1.8 + 32 Example Convert 20 degrees Celsius to degrees Fahrenheit: T(°F) = 20°C × 9/5 + 32 = 68 °F https://www.rapidtables.com/convert/temperature/celsius-to-fahrenheit.html 13 11 Human Comfort: Natural vs Mechanical Creating comfortable interior spaces usually are related to proper mechanical systems or HVAC systems. HVAC refers to Heating, Ventilation, and Air-condition systems. Support occupant comfort and health Protect structure and contents Achieving thermal comfort in a space isn't just about the HVAC design of the engineer but it is also about space planning and material selection which falls under the umbrella of interior design. As Interior Designers, we need to know about thermal comfort. Designing for human thermal comfort doesn’t just involve an optimum interior temperature, but it’s the combination of factors that determine what the optimum interior temperature should be. As a professional in the building industry it is very important to be able to coordinate with engineers and other consultants. 14 2  Principles of Heat Transfer We need to examine what temperature feels comfortable as well as look at how heat moves from our bodies to the surrounding space, from surface to surface and from space to space. Heat always moves from a warmer space to a cooler space, or a warmer surface to a cooler surface. Thermal equilibrium is reached where there is no difference in the temperature between two adjacent spaces, or adjacent surfaces. The greater the temperature difference the faster heat moves down the gradient. For example, in winter, heat is lost much faster to the exterior of a building than it is in the fall or spring. However, in the summer heat is lost from the exterior to the building. 15  Heat Transfer Methods Heat travels from warmer to colder spaces or surfaces by a few different ways: Conduction Convection Radiation 16 Heat Transfer Methods - Conduction Conduction is where heat transfers between molecules. This is heat transfer that involves physical contact between surfaces. For example, when you place a hot cup of coffee on a table the heat transfers from the cup to the table, that is, from surface to surface by conduction. Another example, when you when you walk barefoot on a marble or ceramic floor, heat will move from your body to the floor (from surface to surface) by conduction. 17 Heat Transfer Methods - Radiation Radiation is where heat flows from hotter surfaces to cooler surfaces, with no direct contact. The heat flows through electromagnetic waves. This method of heat flow is the same with the heat from the sun and how it travels to the earth. Evaporation is where heat moves away from water or wet surfaces through moisture. 18 Heat Transfer Methods - Convection Convection is where heat transfers between air and a solid. This could be the heat from an Interior space transferring to the exterior building walls. 19 Heat Transfer -Terminologies Thermal capacity: is the ability of a material to store heat and is roughly proportional to a material's mass or weight. Water for example has a high thermal capacity and is often used as a carrier of heat in building systems. Thermal resistance: a term that acts in response to thermal capacity, that is, materials with a high thermal capacity have a low thermal resistance. In a building the higher the building envelope's thermal resistance the slower heat is lost from the interior to the exterior. Materials with high thermal resistance include Air and Wood; they are good insulators. Materials with low thermal resistance include Glass and Metals. R-value: the measure of thermal resistance for insulators is. The higher the R-value, the greater the thermal resistance level of the insulator. Windows in a building are where most of the heat is lost. 20  Thermal Comfort - Humidity Humidity, which is the level of moisture in the air. High and low humidity can affect health (and comfort). High humidity can cause lots of issues in the interior environment: Mold and bacteria growth Interior finishes to peel or warp. Low humidity can cause: Irritation to the occupants of the space Dry skin, nose and throat. Image1 Architect and Engineers are the main decision makers when it comes to designing the temperature regulating systems of the built environment. Interior Designer can select interior finishes that have a low or high thermal capacity depending on the type of space. 21 18 Indoor Air - Introduction Approximately 90% of human time is spent indoors. Interior environment is susceptible to a wide array of potential air pollutants – typically emitted by : Synthetic building products Equipment Cleaning products Control of Indoor Air Quality is dependent on limiting pollution sources and proper ventilation. Moisture control – important to keeping indoor environments healthy. 22 Indoor Air - Introduction Important considerations for us as designers, and for the general health and well-being of humans. Considerations from the American Lung Association https://www.lung.org/clean-air 23 Indoor Air Quality - Introduction Importance of indoor air quality… “All buildings need to bring in outdoor air for health reasons. Because we use materials that give off toxic components, indoor-air quality (IAQ) has become an important issue. Small buildings, such as residences, have traditionally relied on infiltration to supply the needed fresh air, while large buildings have relied on a designed ventilation system. Because energy-efficient buildings have a tight envelope, all buildings now need a carefully designed ventilation system, and in winter preheating this fresh air will save a great deal of energy.” Norbert Lechner, Heating, Cooling, Lighting (3rd ed), Wiley 2009, page 203. 24 Indoor Air - Introduction Applicable Standards for Indoor Air Quality (IAQ) ASHRAE Standards: Ventilation for Acceptable Indoor Air Quality Indoor Air Quality Guide: Best Practices for Design, Construction and Commissioning ANSI/ASHRAE Standards: Ventilation and Acceptable Indoor Air Quality LEED v4 Standards: - Minimum indoor air quality performance 25 2 Indoor Air Quality ASHRAE Standard 62.1.2013 defines acceptable indoor air quality (IAQ) as: “air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.” Subjective definition to comfort and health. Reflects complexity of identifying contaminants and sources. Difficulty of diagnosing illnesses caused by contaminants in indoor air. 26 2 Indoor Air Quality As buildings become more tightly controlled environments – the quality of indoor air quality (IAQ) – has a greater effect on human health. Reasons for poor indoor air quality in office buildings: Presence of indoor air pollution sources; Poorly designed, maintained, or operated ventilation systems; and Unanticipated or poorly planned uses of the building. 27 2 Indoor Air Quality How engineers approach to deal with indoor air problems: Choosing materials and equipment that limit pollution at its source. Isolating unavoidable sources of pollution. Providing adequate fresh and filtered re- circulated air. Maintaining a clean building and equipment All these strategies are preferable to increasing air flow rates and energy consumption. 28 2 Indoor Air Quality What can Interior Designers do to promote good Indoor Air Quality? Key participant in the renovation of buildings to new uses; Play a significant role in design team; Specify material that do not contribute to indoor air pollution. Research has shown that improving IAQ – can have a significant impact on health and productivity. Increasing health and productivity makes these strategies important and cost effective. 29 2 Indoor Air Quality Illnesses Related to Buildings In the early 1970’s – efforts to conserve heat, and constructing ‘tight’ buildings resulted in poor indoor air quality and ‘sick building’ problems. As a result, building codes have sought to balance energy efficiency with air quality. Currently, careful material selection and ventilation make it possible to build tight buildings with both high energy efficiency and good indoor air quality. Sick Building Syndrome (SBS) – term that relates to symptoms related to workplace health. 30 2 Indoor Air Quality Sources of Pollution Bingelli, Building Systems for Interior Designers, page 224, Table 13.1 31 2 Indoor Air Quality Volatile Organic Compounds (VOC) Chemical compounds that evaporate at room temperature and normal atmospheric pressure (therefore, volatile) and contain one or more carbon atoms (therefore, organic compound). Enter the air when the surfaces of solid materials evaporate – or “off-gas” at room temperature Some materials off-gas VOC’s for a time period, then revert to a safe state Some situations can cause mild to serious health effects from VOC exposure Example – large installation of new furniture or wall partitions, dry cleaning of interior furnishings, large scale cleaning, painting, etc. Period immediately following the finishing of a building – critical for VOC exposure. Flush-out periods may be used to increase ventilation and exhaust VOC’s from a building 32 2 Indoor Air Quality Indoor Air Quality - Equipment Once interior contaminants are removed (VOC’s, other contaminants) – next practical measures are increased ventilation and improved air filtration. Air Cleaning Equipment: Incorporated into the HVAC system Filters air prior to returning to duct system Can also be portable units Equipment capacity is matched to size of room/building Binggeli, Building Systems for Interior Designers, page 33 2 227, Table 13.2 Indoor Air Quality Indoor Air Quality Equipment Air Cleaners - types of equipment Binggelli, Building Systems for Interior Designers, pg 228, Figures 13.3, 13.4, 13.5 34 2  Relevant Resources Fundamentals of HVAC - Basics of HVAC https://www.youtube.com/watch?v=fqvo7bSr6t8 Air Cooled Chiller - How they work, working principle, Chiller basics https://www.youtube.com/watch?v=Ic5a9E2ykjo Fundamentals of HVAC - Displacement Ventilation https://www.youtube.com/watch?v=kB7zMJaFlcw Case Study - Displacement Ventilation in Manitoba Hydro Place http://www.youtube.com/watch?v=xBz e3kgjL-s Guidelines for Indoor Thermal Comfort & Ventilation http://www.hse.gov.uk/temperature/th ermal/factors.htm 35