Hotels on Small Islands - Call for Sustainability Challenges

Over the last couple of years we have had an increasing number of complaints that the rooms are too hot in the summer months. We have opened up rooms, redesigned them taking out walls, installing cedar serpentine louvred windows instead of glass, added windows, expanded doors to increase cross-ventilation, added fans and we have put a layer of reflective insulation inside the ceilings. All this has helped to cool the rooms, but the increasing temperature is negating these effects. The seemingly simple solution would be to install air conditioning units in the rooms.  However when we look at this idea we come up with major reasons for this not being viable. Adding air-conditioning will increase our carbon footprint as the units will be used mostly at nights when we are using the public electricity supply which is generated from oil. This will thus merely add to the effects of global warming and as such is, taken from a global perspective, not responsible. During the day we operate on PV(grid tied) and if airconditioning were to be used, this would mean increasing the size of our PV system as well as that of our LPG backup generator to ensure the day time use of the air-conditioning. This expansion would be at significant cost.  We could say that the comfort of our guests is more important than the warming of the planet and choose to install the latest technology inverter air-conditioning units. Given the design of our rooms this would mean a complete re-structuring: double glazed windows to replace the louvres, shutters to protect the windows during a hurricane, insulation of the walls and new tighter fitting doors to prevent leakage of cool air. In other words an enormous investment to solve a problem for 3 months in the year. Our challenge is find a method to cool our guest rooms that is sustainable, environmentally friendly and effective. We want to avoid using energy intensive air conditioning for the reasons cited above. We think that a possiblity would be to coat our roofs with a white relective layer of insulation. We would be very interested to hear the thoughts of others and receive advice from experts so that we can find the best solution to our challenge.