Building System exam 3

American Society for heating refrigerating & Air conditioning engineers

• focused on building system, energy efficiency, indoor air quality, refrigeration and sustainability within the industry

• promotes a more sustainable world

air temperature

the air temperature of the air surrounding a person

Relative humidity

the percentage of moisture in the air, affecting heat dissipation through sweating

Air motion (air velocity)

the movement of air, which can enhance cooling (like a fan) or create discomfort if too strong

mean radiant temp (MRT)

the average temperature of surrounding surfaces (walls, windows, floors) which impacts how we feel warmth or cold

energy to move water vs air

• it takes much more energy to move heat with air than with water

extended plenum

• in attic space or basement

• less expensive

• more efficient & healthy bc all equipment ductwork are within thermal envelope

air conditioning for small buildings

air conditioning for large multi story buildings

• VAV System

• Evaporative Cooling

All- Air-VAV System

• still single-duct but can have many zones

• VAV- Variable Air Volume- a control box is located where a duct enters a separate zone

• thermostat in each zone controls the dampener inside the VAV box

• Low initial cost & energy efficient+ very common

evaporative cooling

• Cooling Tower

  • cooled water is then used to cool the condenser located elsewhere

• Water is sprayed over hot condenser coils to more efficiently dump heat into the atmosphere

central system locations

• Chiller: When the refrigeration machine produces chilled water

• avoids the large vertical ducts

• less expensive bc it takes lots of energy to move air not water

central system location roof vs basement

roof

• ideal for fresh air intake

• ideal for heat rejections

basement

• easy utility connection

• noise isolation

• no structural loads

air supply

• tree system

  • main trunk- largest

    • Branches- progressively smaller common to use flexible duct

• coordinate with structure

thermal zones

Separated environmental controlled areas

• each with separate thermostat

Relevance of thermal zones

• difference in exposure

• Difference in use

• Difference in rental zones

• Energy efficiency

• Important factor when selecting mechanical system

photovoltaics system types

Utility independent/ Battery Storage

• batteries take a lot of space

• Cost are high

• Replaced periodically

• Safely disposed of

Utility dependent/ Grid Tied

• energy use is net metered

• Metering determines if the system feed energy into the utility system or if energy was drawn from the utility system

photovoltaics system components

• PV panels

• Batteries

• Charge controller

• Inverter

PV panels

These produce the electricity from sunlight. There are typically 10-20 of these

Batteries

Used to store energy, 10-20 deep cycle lead acid batteries

Charge controller

Regulates the charging of the batteries

Inverter

Converts low voltage DC (direct current) power from the batteries into 110 volts AC (alternating current) for use by appliances

hot air systems

• can provide heating, cooling, humidification, dehumidification, filtering, ventilation, & air movement

• Furnaces may be gas or electric

• Good where summer cooling is required

• Heat exchanger prevents combustion air from mixing with room air

hot air system types

Radial- Perimeter system

• Approx. 4’ crawlspace required

• less expensive

• difficult to construct/ install

Extended- Plenum System

• attic space or basement

• less expensive

• more efficient and healthy because all equipment ductwork are within thermal envelope

heat pumps

geo- exchange

• water is used to transfer heat from the heat pump to and from the upper layer of earth (less than 100ft)

• In summer the pumps move heat from indoor to ground acting like heat sink

• In winter heat is moved from ground and pumped inside

low energy heating

cooling

components refrigeration cycle

• Evaporator coil

• Compressor

• Condenser coil

• Liquid refrigerant

• Expansion valve

refrigeration cycles

• refrigerant expands from liquid to gas on the evaporator side

• Condenses refrigerant from gas into liquid

Split system

• type of DX system- “direct expansion”

• Homes and small office buildings

Types of water sources supply

• rain water

• Surface runoff

• Aquifer

• Wells

Types of wells

• Dug wells- Easily contaminated Subject to drought

• Driven wells -

• Bored wells

• Drilled wells

Source of drinking water

Potable water