Hell on earth. Please do not get too up in arms. Despite the higher probability of being murdered in Puerto Rico versus *other* USA states, I am talking about heat, NOT labeling San Juan as a city of sinners. I live on the West Coast, but I can tell you despite the interesting stuff available in San Juan, including better schools, I hate visiting San Juan.
All that concrete beaming the heat at you is like Hell on Earth to me, metaphorically speaking of course, with a healthy dose of exaggeration. However, I was born and raised in the cool Northern climate of Canada's East Coast, and I can tell you that I am certainly a more sensitive instrument when it comes to Puerto Rico's outdoor and indoor temperatures.
According to NASA, "San Juan - we have a problem...". The city of San Juan, like other big cities in the world (particularly those in the Tropics) has a fast rising temperature within the city, which could grow by as much as 8 degrees Celsius hotter than outside of the city by 2050.
If you do not think that is significant, remember that your air conditioning units have to work a little harder, burning more energy, for every %-age of a degree increase. And you do not have to wait until 2050 for that. It's already in full effect, and will grow each year.
It all relates to something called "Albedo", derived from the Latin term meaning whiteness. You can click the link to get the gritty scientific details. However, be assured that for the layman, albedo is simply a measure of how much heat our cities are keeping from the sun, or reflecting back into the clouds. The more heat we keep, the hotter it gets all around us including the air temperature. In fact, every type of material be it concrete, trees, or clothing has an albedo value. But we can also assign this value to a city which is composed of all the roads, rooftops, parks, etc.
The average albedo of the Earth is about 30%. Most land areas range from 10% to 40%. In the tropic countries, cities like San Juan are, on average, only reflecting back about 12% of that heat energy.That means the average area of the earth is reflecting back only about 30% of the heat from sunlight, and absorbing the rest. That's good of course. If we did not have a warm earth, we would not exist! For every increase of 1°F, energy consumption in cities rises from 3% to 8% just to compensate for the Island Heat Effect.
From Wikipedia on Albedo:
Although the albedo-temperature effect is most famous in colder regions of Earth, because more snow falls there, it is actually much stronger in tropical regions because in the tropics there is consistently more sunlight. When Brazilian ranchers cut down dark, tropical rainforest trees to replace them with even darker soil in order to grow crops, the average temperature of the area increases up to 3 °C (5.4 °F) year-round...
In U.S. cities with populations over 100,000, peak utility loads increase 1.5-2.0% for every 1°F (0.6°C) increase in summertime temperature. Steadily increasing downtown temperatures over the last several decades mean that 3-8% of community-wide demand for electricity is used to compensate for the heat island effect.
Do you care about adding an extra 3-8% onto your power bill every few years, *on top* of what we already have to expect due to the world oil crisis, and living a city that is almost unbearable to be outside during the day time?
I am sure you know that wearing light colors keeps you cooler in the sun. That's albedo at work. Wearing darker colors actually leads to a higher incidence of heat stroke. Is the city of San Juan suffering its own "Heat Stroke"?
Let's talk about some fixes. Pilot projects are under way in Baton Rouge, Chicago, Houston, Sacramento, and Salt Lake City. Perhaps we can add San Juan to the list, especially to make sure we consider the Island Heat Effect and how it relates to San Juan's major new developments.
There are basically two root problems here, one is personal is one is global. Globally, city temperatures are increasing, making for less habitable or enjoyable living environments in cities like San Juan and causing major increases in energy consumption and its price tag. Personally, our own comfortability of life is impacted and we have to pay more of our families income towards energy fees in order to keep our homes cool and habitable.
- Do you run from your home to your car air conditioning to avoid the outdoors, and avoid sweating in your clothing long before getting to your destination?
- Are you one of the Puerto Rican's who waits in your car at the mall, engine running with air conditioner blasting, until someone parked close to the entrance leaves so that you can avoid a longer walk through the parking lot?
Solutions come down to city planning and also with projects initiated to specifically address this problem. Personal planning can come down to reducing your own energy bills by modifying your home to reduce temperatures. Stuff as simple as planting shade trees works, but also decisions such as the color of the tile, paint, or roofing material will all have *major* impact. Cool pavement and cool roofs is part of the mandate of the Urban Heat Island Pilot Project (UHIPP).
Shade trees also can make homes and buildings significantly more energy efficient. Scientists estimate that strategically planting trees and vegetation reduces cooling energy consumption by up to 25%. For many, this research comes as no surprise—trees have been used to cool homes for hundreds of years.
Some city planning solutions:
- Modify building code to enforce use of low albedo materials on all new buildings, both residential and commercial.
- Develop a public building standard to include the use of shade trees or roof top gardens to reduce temperature and associated energy expense.
- Choose pavement aggregate for all road projects that has a lower albedo.
- Provide subsidies for home owners and businesses who adopt solutions to help fight the Island Effect of Heat.
- Explore and test new technologies.
- Start a PR campaign to draw the attention of the world. Be a leader in the solutions.
- Lobby for Federal funding for all of the above.
Some personal solutions:
- Take a proactive approach to modifying your home. Be aware of the albedo factor in choosing materials such as outdoor tiling and paint color.
- Explore the idea of rooftop gardens and shade trees.
- Use reflective or light color window shades.
- Write to your major and city council representatives asking them to be proactive in exploring solutions for the Island Heat Effect. Give them some of the above suggestions plus some of your own.
By the way, you might ask: If solar panels are black and designed to absorb heat energy, are they a part of the problem? I found a great post in a QA at Amazon's AskVille that addresses that question:
Solar Panels Impact the Island Heat Effect?
So San Juan, Puerto Rico may not be "Hell on Earth"... but due to the Island Effect of Heat, it is "Hot as Hell". 
The Insider
Sources:
The Use of ATLAS Data to Quantify Surface Radiative Budget Alteration Through Urbanization for San Juan Puerto (PDF, 7,092KB)
