MSc01 - AGB Flashcards
Passive strategies for the warm season
Natural ventilation
External heat gain control
Internal gain control
Bufferzones (thermal mass, building heat capacity):
Evaporative cooling
Building envelope
what is the different types of natural ventilation principles and how are they possible?
Cross ventilation - two openings : W < 5H
One sided ventilation - single opening: W < 2H
Double opening: W < 2*5 H
boyance effect - three openings
combined cross and boyance
what are the driving forces (physics) of natural ventilation?
wind pressure difference across openings - the wind create wind pressure difference accross building which creates flow
boyance effect/air density - hot air is lighter than cold air
What are the parameters of air exchange rate?
window effective opening area
window size
pressure differences
what are the advantages of natural ventilation?
+ No fan, no pipe-work
+ Low energy consumption
+ Large occupant impact and well received by occupants
+ Both ventilation and passive cooling
+ Integrated with the building and can be combined with
other passive energy technologies
what re the disadvantages of natural ventilation
- Natural driving forces not constant or stable
- Limitation with building layout
- Outdoor dust and traffic noise
- Thermal discomfort in winter
- Highly depend on occupant’s control
- Temperature fluctuation
What are the possibilites of ventilation during winter??
mechanical ventilation to get rid of excess heat loads and contaminant air
little openings for natural ventilation that minimizes heat loss
parameters of cooling residental buildings
Cooling in residential buildings is more correlated to solar
radiation than to outdoor temperatures
* Essential to combine solar shading and ventilative cooling
* Can be needed all year, different solutions required for
different seasons
* Mechanical ventilation flow rates to small to be effective
during summer
* Often required when home is not in use or during night,
automatic control often beneficial and openings protected
against rain, leaves, burglary required
how should the ventilation strategies be during different seasons?
Vinter:
Ensidet ventilation
Forår/efterår:
Tværventilation
Sommer:
Kombination af opdriftsog
tværventilation
how are Internal gain controlled?
placing appliances outside of occupation areas, zoning,
how are External heat gain controlled?
solar transmission/ radiation control
window parameters
building orientation
shading
how is a bufferzone created? (thermal mass, building heat capacity):
by thermal mass and using building materials with high heat capacity
What is the main issue in warm seasons?
overheating in rooms, especially rooms facing south, west, east
Passive strategies for the warm season
passive solar gain
Better building evelope
Sunspace
what is the main issue during the warm season?
High energy consumption for heating, high transmission losses in envelope and piping
what are the passive strategies for cold season?
passive solar gain
reducing infiltration
Sunspace / heating conductivity
thermal mass
What is passive heating and what are important factors?
passive heating is using solar gain and solar incidence to heat up a building. the efficiency of this strategy is determained by the effective solar transmissionarea which is determained by window glazing area, g-value and orientation of windows
what is infiltration and how is it reduced?
infiltration is heatloss though the building envelope
reduced by high insulation of the building envelope (air tight)
How is thermal mass used during cold season?
by using interior materials with high heat capacity to store heat though radiation
How is thermal mass used during warmseason?
by using facade materials with high heat capacity to store heat and delay the heat transfer from outside to inside
what is the main issue with regards to natural ventilation:
south facing rooms are overheating, mechanical ventilation is energy-consuming, you need windows towards south to ensure passive heating during winter, in Denmark you need openings towards south and west bc wind = overheating
What i Be18 used for?
Energy steady statecalculations
what are the advantages of Be18?
Simple, it calculates the energy need according to regulations
What are the disadvantages of Be18?
it calculates energy use for the whole building which might not make sense for apartments
doesn’t consider variations in use, enviourment, occupants, seasons, building layout etc.
Considers the upper boundary for energy need
What are the advantages of Bsim?
dynamic simulations that takes different parameters into consideration and it gives hourly results
what are the disadvantages of Bsim?
the data you give is very precise however, nothing is so predictable
the weather data is from past years
how do you design for indoor environmental behavior options?
make things flexible
what is human adaptability and what are the main point of adaptive opportunities?
people adapt to the climate they live in and can be an active part of the building operation. this affords autonomy over enviourments
what does a window afford?
connection to outdoors
view
fresh air
natural light
regulation of circadian rythms
sense of time
what is the role of window openings in a home?
how does the design adress seasonally changing weather and climate, changing occupant needs and climate change challenges
by allowing for flexibility and autonomy for the occupants to interact with their environment and regulate it according to their needs.
neither the weather or people are predictable so…
