Questions and Answers
How do we measure energy?
| Type | Unit |
|---|---|
| Electric | Watt |
| Mechanical | Horsepower |
| Thermal | Degrees |
| Chemical | Calories |
What is a watt?
The watt (W), named after James Watt, is a term used to describe a unit of energy per unit of time.
- 1 watt = 1 energy/time = 1 joule/sec = 3.412 btu/hr = 1.34 x 10-3 hp
- 40-100 W = A typical household incandescent bulb
- 200 W = A person walking up a flight of stairs
- 100,000 W = Output of an automobile engine
- 1 Megawatt (MW) = Energy used to power 1,000 US homes
How much does solar power cost?
A residential solar energy system typically costs about $8-10 per Watt. Where government incentive programs exist, together with lower prices secured through volume purchases, installed costs as low as $3-4 watt - or some 10-12 cents per kilowatt hour can be achieved. Without incentive programs, solar energy costs (in an average sunny climate) range between 22-40 cents/kWh for very large PV systems.
Source: http://www.solarbuzz.com*
The goal of the Solar Decathlon is to reduce this cost to $0.10/kilowatt by 2015
What's all this talk about being "carbon neutral" by 2030?
In 2006, the US Council of Mayors ratified the "2030" protocol that establishes this goal:
"To promote integrated/high performance design including resource conservation resulting in a minimum 50% or greater reduction in the consumption of fossil fuels used to construct and operate new and renovated buildings by the year 2010 and promote further reductions of 10% or more in each of the following 5 years."
Source: High Performance Building Position Statements, The American Institute of Architects, Washington, DC, 2005.
The schedule for reducing fossil fuels is as follows:
| Year | % Reduced |
|---|---|
| 2010 | 60% |
| 2015 | 70% |
| 2020 | 80% |
| 2025 | 90% |
| 2030 | 100% |
Source: http://www.architecture2030.org*
Say Watt?
We're solving problems that involve a lot of technical jargon. Here are some terms you might not be familiar with yet. Pop quiz in 5 min. Ready? Go...
- PV: Photovoltaic ::
- Generates an electrical current by converting the sun's energy
- BOS: Balance of Systems ::
- The rest of the equipment necessary to help convert and store energy generated by PV's. Ex: Inverters
- EEM: Energy Efficient Measures ::
- Systems and Materials that increase the energy efficiency of a house. Ex: thinted window film
- LCOE: Levelized Cost of Energy ::
- A cost for energy after including a number of factors including the cost of the PV array and the BOS for comparison and analysis purposes.
- SIP: Structurally Insulated Panel ::
- A panel, typically with 6" of foam insulation used as a structural material for making buildings. This is an energy efficient alternative to conventional wood framing