Duct design is a critical part of passing warm or cool air throughout a building. There are primarily four major types of ductwork that distribute and intake air in a Heating Venting and Air Conditioning (HVAC) system. The trunk and branch method, the radial method, the spider method and the perimeter loop all perform this task in different ways and usually correspond to a particular building type.

The spider style of duct design is similar to the radial configuration, but slightly more efficient. In this configuration a few main ducts stem off from the furnace, but once these ducts near the rooms, they split off in multiple directions to reach the appropriate vent. The configuration often looks like the legs of a spider.

The perimeter loop is probably used least by HVAC duct professionals. This configuration takes the radial method's use of individual ducts leading to every room, but adds an additional element. Each individual duct is connected around the perimeter of the building by added ducts, making a loop that passes excess hot or cool air to the next vent.

The return air grille covers a register that allows air to flow into the heating and cooling system. Most grills are adjustable, allowing people to shut a room off so the furnace cannot pull air out of it. The amount of air allowed through the air grille can also be moderated, as for example if people want more cold air pulled out of downstairs rooms in the winter and less of the hot air upstairs pulled through the heater.

There are several different strategies you can use for determining home humidity, none of which require the purchase of expensive equipment. Drop three ice cubes into a glass, add water, stir and wait for three minutes; if moisture does not form on the outside of the glass, you may need a humidifier. On the other hand, if you notice frequent fogging of your windows or moisture buildup on closet walls and room ceilings, you may have too much humidity in your home.

 

A BTU, short for British thermal unit, is a basic measure of thermal (heat) energy. One BTU is the amount of energy needed to raise the temperature of 1 pound (0.45 kg) of water by 1° Fahrenheit (0.55° Celsius). In other words, if 16 ounces (0.47 l) of water at 59°F (15°C) were poured into a stovetop pan and the gas burner turned on, it would take 1 BTU to raise the temperature of the water to 60°F (15.6°C). If the pan was left on the gas flame, the water would eventually reach the boiling point of 212°F (100°C), which would take about 153 BTUs. This non-metric unit of measure is commonly employed only in certain countries — including the US — and is used mainly to rate the heat output of fuels and appliances.

Climate control systems are used to provide heating and cooling in residential and commercial buildings. These systems are part of the building's heating, ventilation, and air conditioning (HVAC) system, and are typically installed and maintained by specialty contractors. There are a number of different types of climate control systems that may be used, depending on the size and function of the building, as well as the needs of occupants or residents.

HVAC systems are used to improve building comfort, increase productivity, and to preserve building components over time. Effective climate control systems not only improve the well-being of occupants, but also help to keep moisture and humidity levels in check. While excess cold or heat can lead to burst pipes or warped furnishings, unchecked moisture and humidity can cause mold or rot.

Most climate control systems in larger buildings are monitored using performance management software. These performance monitoring systems allow operators to control heating and cooling levels using a computer program. Ventilation and humidity levels can be adjusted, and air quality is automatically monitored for carbon dioxide levels and other contaminants. Building performance monitoring helps the building owner to balance energy efficiency, comfort, air quality and maintenance in one simple system.

Geothermal cooling is a process by which shallow ground is utilized within a system to regulate temperature. The upper 10 feet of the earth's surface holds a stable temperature between 50° to 61°F (10° to 16°C). This stable temperature is harnessed, using a geothermal device, to draw heat energy out of a system and thus transfer the cool temperatures into a warmer area.

Surface temperature has almost no effect on the ground underneath the frost line. Using this knowledge, a pump can be placed under the ground, in an area such as a basement, that effectively pulls the cool sustaining temperature from the ground. This device is connected to a loop of copper tubing or high-density polyethylene, which is literally buried underneath the earth's surface. 

All refrigeration and air conditioning processes use a gas to facilitate the transfer of heat between the air-conditioned area and the outside atmosphere. This process relies on the use of a compressor to increase the pressure in the evaporator section, or air conditioned area, of the system which in turn allows the absorption of heat from that area. This absorbed heat and any heat generated by the compression process needs to be rapidly removed from the refrigerant in the outside, or condenser, part of the system so that the cycle of heat transfer can be repeated. This is typically done by allowing the hot refrigerant to circulate through a series of tubes exposed to a fan induced airflow.

Portable indoor air conditioners are usually used in small rooms or locations that don’t require temperature regulation on a regular basis. For example, in countries where temperatures rarely become uncomfortably hot, a portable air conditioner may be the best solution because it doesn’t require any installation. Portable units are often placed on rollers in a room and require a hose or vent that connects the conditioner to the outside in order to remove heat. These units come in a variety of power levels to suite the needs of a particular room size.

Understanding the heating load is important. When installing a heater, if the heater is too small for the space, it will struggle to heat it, and use a lot of energy in the process. On the other hand, if the heater is too large for the space, it will not operate efficiently, generating wasted energy which adds to the lifetime cost associated with the structure. Heating load can also be an important factor when evaluating sustainability or thinking about changes which could be made to make a structure more sustainable.