Heliotactic Press

Interdisciplinary exploration of solar energy conversion, photovoltaics, and integrative design, and scientific philosophy.

Google SketchUp: Where is the Sun? 2010/01/24

Filed under: Solar Education,solar energy — nanomech @ 11:49
Tags: , , ,

As a researcher and educator in solar conversion systems design, I am sharing my concern about Google SketchUp for professional use and energy analysis. Through a multi-week correspondence with an unnamed member of the Google SketchUp team, I have learned that the team is unaware of the accuracy of the algorithms underlying their ShadowInfo and ShadowInfoObserver classes, and do not have the resources to collaborate to attribute source documents to the error in their models. Simply put, they do not know if the sun is where it should be for a given location/time on Earth. These core algorithms relate the solar Equation of Time (describing the difference between apparent solar time and mean solar time) to latitude position, solar declination, solar azimuth, and hour angle. If you and your colleagues find this of interest, I would ask you to contact the SketchUp team directly (sketchup-help@google.com) with common concern, as I have not had success in encouraging SketchUp to make this important information transparent to the user base. Arguably, it would not be a challenging problem to solve, if the user base could simply see the “snippets” of geometry algorithms. However, I am concerned that there may be legal consequences to those who use SketchUp for professional applications (such as your own firm), should SketchUp be found to be in significant error when used to prove or disprove data.

From the Google SketchUp Team:

“We’ve done some investigation over the weekend, but we don’t actually have any more information to provide. We don’t have a particular reference document, paper, or source for our algorithms, so there isn’t a location to which we could point you for reference. Furthermore, the solar calculations were implemented early on in SketchUp’s development, and the people who initially worked on them are no longer with the company.”

Thank you for considering this unusual failing in an otherwise highly useful software piece.

Dr. Jeffrey R. S. Brownson
Dept. of Energy & Mineral Engineering
The Pennsylvania State University
nanomech@psu.edu

 

Sustainability and Technology in the Habitable Environment 2010/01/02

In the USA, we  divide energy demand into four economic sectors: Industry, Transportation, Commercial Buildings, and Residential Buildings. By combining the Commercial and Residential sectors, we observe that 41% of our energy demand is derived from building environments (the habitable environment), and about 40% of our carbon emissions are derived from buildings. Additionally, Americans have been observed to spend 90% of their time indoors. This is a big chunk of power that we can work to make more sustainable! So what is sustainable energy technology, and why should we even use it?

Energy Flows (supply and demand) USA 2008

As seen in the figure, the majority of our energy supply has been from unsustainable sources (with the loose exception of hydropower). At some point I would like to provide a similarly enhanced figure that demonstrates the energy losses associated with supply and demand (for the curious: see here).

In terms of energy technology development and entrepreneurship, we may establish four generic divisions: energy supply, demand, storage/capacity, and usage. But energy technology development has a historical balance to be made with design, planning, policy and regulation. So why should we pursue sustainable energy solutions at all, or what is our sustainability ethic? Sustainability in planning and international policy can be addressed using the 1987 UN document Our Common Future (derived from the 1987 Brundtland Commission). It’s not the end-all document, but I would call it a good start for discussion and a must read for those learning about the history of modern sustainable energy solutions. The following list of general principals, rights and responsibiliteis comes directly from the Brundtland Commission report, Annexe 1:

Fundamental Human Right

1. All human beings have the fundamental right to an environment adequate for their health and well being.

Inter-Generational Equity

2. States shall conserve and use the environment and natural resources for the benefit of present and future generations.

Conservation and Sustainable Use

3. States shall maintain ecosystems and ecological processes essential for the functioning of the biosphere, shall preserve biological diversity, and shall observe the principle of optimum sustainable yield in the use of living natural resources and ecosystems.

Environmental Standards and Monitoring

4. States shall establish adequate environmental protection standards and monitor changes in and publish relevant data on environmental quality and resource use.

Prior Environmental Assessments

5. States shall make or require prior environmental assessments of proposed activities which may significantly affect the environment or use of a natural resource.

Prior Notification, Access, and Due Process

6. States shall inform in a timely manner all persons likely to be significantly affected by a planned activity and to grant them equal access and due process in administrative and judicial proceedings.

Sustainable Development and Assistance

7. States shall ensure that conservation is treated as an integral part of the planning and implementation of development activities and provide assistance to other States, especially to countries of the global South, in support of environmental protection and sustainable development.

General Obligation to Cooperate

8. States shall cooperate in good faith with other States in implementing the preceding rights and obligations.

Looking over this entire document, I find interesting underpinnings driving sustainable planning and design of energy flows. It is interesting that the argument here is much more than just a caution against climate change and loss of habitable space. Wow: inter-generational equity and ecosystem maintainence–heavy topics to consider. Additionally, the concept of Managing the Commons in Ch. 10 suggests an international valuation of common human resources that fall outside of national jurisdictions, but have critical importance due to ecological and economic interdependence.

And back to the technologies for the habitable environment:

For sustainable energy applications, an energy supply technology might take the form of algae-based biodisel production, wind power, or solar hot water (we typically call this division renewable energy). An energy demand technology addresses the management of the demand side of energy use (we typically term this division energy efficiency), specifically including efficiency in appliances and HVAC systems, weatherization of homes, and new lighting designs. Energy storage and capacity technologies are often lumped with other divisions, but they do include a significant share of tech: water tanks, phase change materials embedded in the walls, green roofs, batteries and ultracapacitors, and even the electrical power grid (to a certain extent). Finally, energy usage technologies are some of the more interesting developments of late, as they take advantage of modifying human behavior, just like the “Prius (or Honda Civic) effect”. Humans work well when given feedback (it’s like a game!), and much of our energy Demand (in the generic sense of the figure above) can be dramatically shifted toward reduction due to smart systems that inform you instantaneously as you consume energy. We used an amazing system for live monitoring by the company Noveda for the Natural Fusion home in the 2009 Solar Decathlon–very very cool technology.

We often hear the popular media discussion on buzz terms of “renewables” and “energy efficiency”. I have found that the innovation in the field of sustainable energy for the habitable environment is developing sufficiently to merit this new subdivision of scope. Perhaps this will even develop new discussions to refine the divisions for useful application in industry and transportation sectors.

 

 
Follow

Get every new post delivered to your Inbox.