SHOWN ABOVE IS A HVAC SYSTEM IN A TYPICAL UNCONDITIONED ATTIC
The Annual Energy Outlook (AEO) and Residential Energy Consumption Survey (RECS) data indicate that heating and cooling are the most significant uses of electricity in homes. During extreme heat events, the demand for cooling can cause energy systems to overload and require utilities to institute controlled rolling blackouts to avoid power outages. Hot, sunny summer days can also lead to higher roof and pavement surface temperatures, which are often 50–90°F (27–50°C) warmer than the ambient air temperature in cities. This can cause temperatures in developed areas to be as much as 22°F (12°C) higher than in less-developed regions. These extreme temperatures can have significant impacts on a community's environment and quality of life, leading to increased energy consumption.
SHOWN ABOVE IS THE TYPICAL DEGREE CHART ON THE COMMON HVAC SYSTEMS
The main issue with high or low temperatures is that they can have a serious effect on the efficiency of Heating and Cooling Air distribution ducts. These ducts are designed to provide conditioned air from heating and cooling systems to living spaces while returning the same amount of air from the living spaces to the conditioning system. Studies have shown that electricity consumption for cooling increases by 1.5-2.0% for every 1°F (0.6°C) increase in air temperature, starting from 68 to 77°F (20 to 25°C).
SHOWN ABOVE IS THE TYPICAL HVAC DUCT SYSTEM
On a hot summer day, when the outside air temperature can reach 95 to 97 degrees F., the temperature in an uninsulated or poorly insulated house attic can sky rocket to 150 to 160 degrees F. This creates a significant cooling load for a home air conditioner as the temperature difference between the inside and outside air increases. Long duct runs can cause occupant discomfort, especially during the winter months, as rooms served by these long duct runs can experience a "COLD BLOW" due to the low heating supply air temperatures. To reduce the need for insulation and minimize conductive losses and gains, any ducts should be located within the conditioned space and exposed to indoor air temperatures.
SHOWN ABOVE IS A TYPICAL TEMPERATURE SIMULATION
The air distribution ducts in unconditioned spaces such as attics, crawlspaces, garages, or unfinished basements are made of thin materials that conduct heat or cold quickly. As a result, up to 30 percent of the energy used to heat and cool the air is lost through the ducts, leading to an increased workload for the equipment. This means that the equipment has to work harder to make up for the energy lost in these spaces due to the extreme winter and summer temperatures.