If you wish to offset your carbon footprint for your travel to/from Costa Rica, or for a home’s construction, there are a number of resources available – here are two we like, one in Costa Rica, one in the U.S.:
Reforest the Tropics, Inc. is a Costa Rican applied research program demonstrating climate change mitigation through sustainable farm forestry. They create forest areas in Costa Rica as long term carbon sinks. You can participate by sponsoring a 1 hectare (2 1/2 acres) personal forest designed to offset an estimated 25 tonnes of CO2 annually, the amount that RTT estimates a typical family or couple generates each year.
The Carbon Fund is a U.S. provider of offsets. Using their calculators two flights from Washington D.C. to San Jose and a rental of a Hyundai Tucson 4x4 would generate 1.6 tons of CO2 and cost $16 to offset in their system. You can use their calculators to check your own CO2 generation and their offset methods.