TEQ Flashcards
List at least six key properties of a sustainable building
GPT:
1 Provide specified functions and services with high quality and reliability
2 Provide healthy and comfortable indoor enviroments and minimize the exposure
to toxic materials
3 Have a low life-cycle enviromentalö footprint (Less C02, no impact on flora,
fauna etc.)
4 Are constructed in a way such as to minimize embodied energy and resource
depletion, and conserve non-renewable energy and rare materials.
5 Have an aesthetically pleasing external/internal shape and design/layout
meet required social needs and criteria
6 Operate at an overall cost considered attractive/acceptable to all stakeholders
involved, and have a high real estate value
Describe the key benefits of a sustainable building
Lower life-cycle resource consumption (water, energy) and related emissions, and lower impact on local communities
Lower operating and maintenance costs and related overheads – greater profitability
Greater real estate value
Better indoor thermal climate and air quality
Increased occupant comfort, health and satisfaction (residential)
Increased worker productivity, and decreased absenteeism (commercial)
Better (e.g. corporate) image/profile
Deferred investments (e.g. for power generation)
Access to economic/market incentives (tax credits, rebates, low-interest loans and other financial support mechanisms)
For what key applications do we need energy in buildings?
GPT: Energy in buildings is needed for heating, cooling, lighting, appliances, ventilation, and various electrical and mechanical systems.
- Thermal comfort control, energy for controlling heating, cooling and the thermal balance (radiation, transmission etc.)
- Indoor air quality management, to achieve that we need energy to control ventilation, filtration, air handling.
- Hygenic requirements, domestic hot water and sanitation (Toilet)
- Energy distribution
- Building operation and control, activites to operate, manage and maintain buildings.
- Transport systems (Elevators, lifts etc)
- Electric appliances and equipment, such as central vacuum systems, kitchens,
TV, laudries and pools
Describe the key categories of heat gains and losses in a building.
Heat gains
- Internal heat gain (Electric suppliances such as TV, kitchen, lamps, people etc)
- Solar heat gain from radiation
- heating from systems
Heat losses
- Transmissions through windows
- Transmissions through facade
- Transmissions through ground floor
- Thermal bridges
- Ventilation and infiltration loss
What is a smart building?
A smart building is not a building with high standards at the moment which is
constant. Smart is when the building adaptively responds to changing conditions
to achieve a good indoor climate and promote health, well-being and productivity of its occupant.
What is a data-driven smart building?
GPT: A data-driven smart building utilizes sensors and data analytics to make informed decisions and optimize building performance.
EXTRA:
A smart building uses connectivity, software, and data to enable efficient operations and economical use of resources, while creating a safe and
comfortable environment for occupants. Smart buildings may use a mix of a wide range of existing technologies, Internet of Things (IoT) devices, building
management systems (BMS), analytics, and artificial intelligence (AI).
Can include continous data quality validation and assurance
A data structure that facilitates storage and analysis in the cloud.
Automated dispatch of digital commands from cloud-hosted data analytics and/or human decision processes over a suitable “digital platform” interface
Extraction of useful information from the data in order to inform control processes in the building.
Describe the purpose of sustainable building technologies and systems
They provide smart, useradapted, comfortable and productive indoor enviroments with high energy and resource efficency, high cost-efficency, high user/customer satisfaction and value, and smallest possible enviromental impact.
- Give a comfortable and productive indoor enviroment
- High energy and recource efficency
- High cost efficency
- High user/customer satisfaction and value
- Smallest possible enviromental impact
How does ASHRAE describe human thermal comfort?
GPT: ASHRAE describes human thermal comfort as the state of mind that expresses satisfaction with the thermal environment.
Describe the key parameters that define human thermal comfort
Thermal comfort is defined by these components:
- Air temperature
- Radiant temperature
- Air movement
- Relative humidity
- Metabolism
- Insulation
- Air temperature
- Relative Air Humiditity
- Metabolism rate (MET) (activity rate), how much movement? Are the occupant sitting, standing, walking or running?
- Clo value, how much cloths does the occupant have?
- Air velocity
- Mean radianty temperature
Explain the terms “Met” and “Clo” in the context of human thermal comfort. Which units are
met and clo expressed in?
MET stands for metabolic rate and describes the activity level, causing internal heat gain.
1 MET= one person sitting still on a chair = 58W/mˆ2
(The energy generated from the human body)
Clo stands for clothing isulation /thermal insulation unit. It’s describing the amount of clothing the occupant is wearing and impacts the heat transport to
and from the body.
1 CLO = “full suit”, pants, shirt and jacket = 0,155K*mˆ2/W
Explain the terms “air temperature”, “mean radiant temperature”, “operative temperature”
and “equivalent temperature”
Air temperature T(a) - The average temperature of the air around us. In an indoor setting, this means that the air volume in a room is considered “well mixed” = that the same conditions are valid at every point in the air volume.
(Temperature of the air sourrounding the occupant).
Mean radiant temperature T(r) - is another term, it describes the average temperature of the sourrounding surfaces, taking into account their view factors.
view factors - how well another surface can see another surface will affect how much radiative heat flux which leaves the object.
Operative temperature T(o) - The mean value of the air temperature and the mean radiant temperature. It’s derived
from air temperature, mean radiant temperature and air speed.
Equivalent temperature T(eq) - A concept that include air temperature, mean
radiant temperature, clothing, activity and air velocity.
Explain the terms “Actual Mean Vote (AMV)”, “Predicted Mean Vote (PMV)”, “Actual Percent
Dissatisfied APV)” and “Predicted Percent Dissatisfied (PPD)”
Actual Mean Vote (AMV) - How real people assess the thermal comfort at a specific point in time and place, this is a measurement on a scale from -3 to 3, where -3 the person think it is cold and +3 is hot.
Actual Percentage Dissatisfied (APD) - How many persons in the room are dissatisfied with the thermal comfort at a specific point and place regarding if they think it’s too hot or too cold.
Predicted Mean Vote (PMV) - A prediction of the perceived occupant thermal comfort in a room based on a calculation including the factors as air
temperature, mean radiant temperature, relative humidity, air velocity, metabolic rate and the clothing factor. The scale is based on the AMV and you
get a result between -3 to +3.
Predicted Percentage Dissatisfied (PPD) - The percentage of the occupants in a room would be dissatisfied with the thermal comfort, either thinking it is too
cold or too warm.
We can’t expect thermal comfort in every point in a room, only in a defined space which is called occupied zone. Specific in sweden it’s limited between to horizontal lines, one line 0,1m above the floor and the second one 2,0m above the floor. It’s also limited from 0,6m from exterior walls and 1,0m from windows
and exterior doors.
Describe the term “occupied zone” using a simple sketch
In Sweden:
0,1-2,0 meter height, 0,6 meter from external wall and 1,0 meter from window
Explain (using a graph) the relationship between Predicted Percent Dissatisfied (PPD) and
Predicted Mean Vote (PMV). What is the lowest achievable PPD-value and why can lower
PPD-levels not be achieved?
the PPD can never be 0 because of individual differences in the thermal comfort perception, with different words, people don’t think exactly the same. People can have different thermal comfort perception because of:
Deviation in metabolic rate at equal levels of activity
Different in body surface/volume ratio
Healt - genreal fitness, disease, stress, tiredness
Gender
Age
Acclimatization
Expectations!
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How does the International Society of Indoor Air Quality and Climate (ISIAQ) define the term
“Indoor Air Quality (IAQ)”, and how does the American Society of Heating, Refrigerating and
Air-Conditioning Engineers (ASHRAE) define the term “Acceptable Indoor Air Quality (IAQ)?
IAQ - An idicator of the types and amounts of pollutants in the air that might cause discomfort or risk of adverse effects on human or animal health, or damage to vegetation.” (ISIAQ)
They discuss a indicator of types and the amount of pollutants.
Acceptable IAQ - “air in which there are no harmful concentrations of contaminants as determined by cognizant (having knowledge or awerness)
authorites and with which 80% or more the exposed occupant do not express dissatisfaction (ASHRAE).
They discuss air which have been proven by cognizant authorites and where at least 80% does not feel/express dissatisfaction.
Provide at least four examples of indoor air pollutants. List their sources and (potential)
health effects
VOCs (Formaldehyde) (from building materials and furnishings) - Eyes and mucous membrane irritation
CO2 (from occupants) - Dizziness
Radon (from the ground) - Lung cancer
Particulate matter, PM (from various sources) - Lung diseases and cancer
How can poor indoor air quality impact users/occupants in indoor environments?
GPT: Poor indoor air quality can lead to health issues, including respiratory problems, allergies, fatigue, and decreased productivity for building occupants.
(Sick building syndrome: headache
Drowsiness
Eye irritation
Nose and throat infection etc.)
Provide at least three examples of services provided by building control systems
GPT: Building control systems provide services like HVAC control, lighting control, security and access control, energy management, and building automation.
- Safety ( indicate hazard, air quality)
- Security (Unautharized acess)
- Comfort (thermal and visual)
Three components in a control system:
Sensors (input, maybe meusering temperature and amount of daylight)
Controllers (reacting to the input and send a message to the controlled device if
it should react or not).
Controlled devices (output, what the system is supposes to do with the respons, give heat och cold air for example)
What are the characteristics of an efficient system according to classic control theory?
GPT: An efficient system, according to classic control theory, should be stable, provide a fast response, and have minimal overshoot and oscillation.
An efficient and ideal control system is one that drives the controlled variable to
the desired state (reaches set point with little or no offset), does so in as short a settling time as possible, with as little overshoot as possible and in the most efficient/optimal way as possible.
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Name at least five obstacles to designing an efficient control system
GPT: Obstacles to designing an efficient control system include system complexity, uncertainty, sensor limitations, control algorithm design, and cost constraints.
System time lags
- Transfer lag (the time it take to respond from the input)
- Transport lag (respond to output)
Sensor
- location
- bias
- drift
- uncertainty
- Time constant
- Hysteresis
How are the terms “state” and “state space” defined by Modern Control Theory?
GPT: state” represents the current condition of the system, and the “state space” is the set of all possible states.
State - it refers to a snapshot in time of a system describing its behaviour with a minimum set of variables
State space - describes all the possible states that a system can attain
List and describe the key issues that Modern Control Theory concerns itself with.
GPT: Modern Control Theory concerns itself with stability, controllability, observability, and optimization of control systems.
EXTRA:
Observability: How well internal states of a system can be inferred from knowledge of its external output It means that using the sensor data we collect (output) we can describe our dynamical system with satisfactory accuracy (predict future states)
Controllability: ability of external input to move the internal state of a system from any initial state to any other state in a finite time interval. It means given a specific external input we can push/drive the system to any desired state within our state-space.
Stability: Describes the ability to maintain a reached state
means once we reached a desired state in our state-space we are able to maintain that state over a prolonged period of time (steady state).
Describe three Building Management System control levels commonly found in the built
environment.
- Field level where all the physical sensors, controlled devices live
- Automation level where the controller is implemented
- Management level is where the supervisory control and logging takes place
Nine basic technologies are typically used in geothermal energy systems. List at least five of
these and briefly explain their main features.
Horizontal GHEX - Ground Heat Exchanger, is using your backyard or the bottom of lake or river etc. as a thermal battery. In this system cables is placed
beneath the ground or water surface to load heat or dissipate heat with help of the constant temperature in the ground or water.
Borehole HEX - Vertical Borehole GHEX is a effective conductive heat transport system, and the most common type is u-loop, but can also be a straight pipe system. The borehole is around 100-300m deep and 10-15 cm in diameter. The hole is filled with a collector tube which contains cold bearer fluid, for example
bioethanol water mixture.
Groundwater HEX
same type as when you do groundwater well for drinking water. mostly you are
looking for soft formation (tex clay) with groundwater flow. Mostly convective heat transfer. The temperature will be more even than the ground since you are extracting groundwater from the ground. You distract the water from the undisturbed ground.
BTES
BTES system contains several/multiples borrholes to a deep heat storag (resemling standard drilled wells) and can be used for cooling as for heating.
Very efficient for public and office buildings, because the fairly need a balance of cooling and heating.
ATES
ATES stand for Aquifer Thermal energy storage and is made of at least two wells (one cold and one warm well) that can draw from the same or different aquafiers. The cold well is used to store cold water and the warm well is used to store warm water. Depending if the building needs cooling or heating it will use a pump to reject either warm or cold water from the well and use it and then pump
to the other well.
