D

Dashboard

A software-based control panel for one or more applications, network devices or industrial machines. It displays simulated gauges and dials that are designed in a similar fashion to an automobile dashboard.  It can be used for monitoring building energy use, water use, carbon emissions and renewable energy generation.

Daylighting

The use of controlled natural lighting methods indoors through skylights, windows, and reflected light.

Debt service

Periodic repayments of a loan, with a portion of the payment applied to interest and the balance applied to repayment (amortization) of principal.

Deconstruction

A cost-effective way to remove residential and commercial structures to maximize material recovery. Performed mostly by hand, this method can result in the salvage of up to 85% of a building's material for reuse. Deconstruction is an alternative to traditional "wrecking ball" demolition.

Degree days

The difference between the average daily temperature and 65 degrees Fahrenheit, used as a baseline. This measure is used to estimate building energy needs. It is also a quick way to compare the severity and character of a climate. A heating degree day is counted for each degree below 65 degrees reached by the average daily outside temperatures. For example, if, on a given day, the daily average temperature outdoors is 30 degrees, then there are 35 degrees below the 65 degrees. Thus, there are 35 heating degree days for that day. Areas with more than 5500 HDDs per year are characterized by long cold winters. Areas with less than 2000 HDDs per year are characterized by very mild winters. Reverse this process (degrees above 65 degrees) to calculate Cooling Degree Days. Areas with more than 1500 Cooling Degree Days (CDDs) are characterized by long hot summers and substantial cooling requirements. Areas with less than 500 CDDs per year are characterized by mild summers and little need for mechanical cooling.

Delivered energy

Energy delivered to the building, like gas, oil or other fuel, electricity (see effective energy and primary energy).

Demand control ventilation

Ventilation provided in response to actual number of occupants and occupant activity.

Demand-side waste management

Prices whereby consumers use purchasing decisions to communicate to product manufacturers that they prefer environmentally sound products packaged with the least amount of waste, made from recycled or recyclable materials, and containing no hazardous substances.

Design conditions

The exterior and interior environmental parameters specified for air conditioning (heating, cooling, and ventilation) and electrical design for a building.

Design for the Environment

DfE is a process used in many industries to help organizations improve the environmental impact of their products and services throughout the development process. Each industry approaches this process differently and there are few standards. In addition, for small manufacturers, this is often seen as a time-consuming and expensive additional cost. This is still a new process for most designers and engineers but it is slowly growing. 

Design temperatures

Temperatures used for modeling energy calculations. They are established for winter and summer for specific cities, representing the calculated low and high extremes.

Desuperheater

A device for recovering superheat from the compressor discharge gas of a heat pump or central air conditioner for use in heating or preheating water.

Dessicant

A drying agent, such as silica gel, which can be used to reduce latent cooling loads.

Detention pond

In stormwater management, ponding of runoff in pools and basins for water-quality improvement and flood prevention.

Development footprint

The area on a project site that has been impacted by any development activity.  Hardscape, access roads, parking lots, non-building facilities and building structure are all included.

Dewpoint

The temperature at which water vapor in air will condense into liquid water at a given relative humidity.

Disassembly

Taking apart an assembled product. Design for disassembly in buildings allows building components to be readily reused and recycled.

Diurnal flux

The difference between daytime and nighttime temperatures. A diurnal flux of 25 degrees Fahrenheit or above indicates an arid climate suitable for mass building construction.

Drip irrigation

Above-ground, low-pressure watering system with flexible tubing that releases small, steady amounts of water through emitters placed near individual plants.

Drought tolerance

The capacity of a landscape plant to function well in drought conditions.

Dry bulb temperature

The temperature of air indicated by an ordinary thermometer.

Dry detention pond

A surface vegetated basin used to provide flow control for a particular drainage basin. Stormwater temporarily fills the dry detention pond during large storm events and is slowly released over a number of hours, reducing peak flow rates.

Drywell

A structural subsurface facility with perforated sides or bottom, used to infiltrate stormwater into the ground.

Dual-flush commode

Water-saving toilets with two water-saving options – 0.8 gallon/flush for liquids, and 1.6 gallons/flush for solids.  These are available in flush valve (tankless) (commercial), and tanks (residential) models.

Duct blaster

A calibrated air flow measurement system designed to test and document the airtightness of forced air duct systems in both houses and light commercial buildings. The fan is connected directly to the duct system in a house, typically at a central return, or at the air handler cabinet. With the remaining registers and grilles temporarily taped off, duct airtightness is measured by either pressurizing or depressurizing the duct system and precisely measuring the fan flow and duct pressure.

Durability

A factor that affects the life cycle performance of a material or assembly. All other factors being equal, the more durable item is environmentally preferable, as it means less frequent replacement. However, durability is rendered moot as a factor if the material is replaced for aesthetic reasons prior to it actually wearing out.