passive_systems Flashcards
(15 cards)
What is the basic principle behind passive heating systems?
They accept sun when needed, block it when not, and move air via natural convection to heat or cool spaces.
What is a Trombe wall?
A passive solar design with a thermal mass wall behind glazing that absorbs solar heat during the day and radiates it at night.
How does a Trombe wall provide passive cooling?
By opening top exterior vents and closing interior ones, hot air rises and exits, drawing in cooler air to create a breeze.
Why are Trombe walls uncommon despite being effective?
They look unusual (glass in front of a concrete wall), are hard to keep clean, and require vent operation.
How can you automate passive systems like Trombe walls?
Use sensors and electronic controllers to open/close vents/windows based on time, temperature, and season.
What is a greenhouse used for in passive design?
Captures solar heat, can be used as occupiable space, and facilitates convective air movement for heating or cooling.
How can a passive system use a cellar for cooling?
By pulling air from a cool cellar using convective current driven by solar-heated greenhouse air.
What is a solar chimney?
A vertical shaft that heats air with solar gain, creating an upward airflow that pulls cool air from below.
How does a wind scoop work?
Usually faces away from wind to capture eddies created over the building, pulling air through the space.
What is the ground temperature a few feet below grade year-round?
Approximately 52–55°F, consistent across seasons.
How does geothermal heating/cooling work?
It exchanges heat with the ground via pipes, transferring heat into the ground in summer and extracting it in winter.
What are the main costs associated with geothermal systems?
High initial installation cost due to drilling; low operating cost over time.
Why must geothermal systems be part of long-term plans?
They require 15–20 years to pay off initial costs but offer efficient heating/cooling for 30+ years.
What materials are good heat sinks for passive heating?
Concrete, stone, water, tile – materials that store and slowly release heat.
Why are inside light shelves problematic in hot climates?
They allow solar heat gain inside the building, unlike exterior shelves that block high summer sun.
