Hawaii’s climate presented unique challenges for the planning and designing of constructions that would be healthy and pleasing for their occupants. The mostly constant high temperature in combination with the high humidity, has forced people to locate and design their first settlements in ways in order to provide them shade, ventilation and sufficient light. Possibly the most important priority of settlements was their resilience and the traditional buildings had a number of wind and thermal resistance characteristics. The houses were built of palm thatch with relatively steep hipped roofs, well interwoven (using significant amounts of flat braided cordage) with no windows and few doors. The porosity of the building materials prevented excessive heat build-up within the interior spaces. However, traditional methods and materials had disadvantages such as low durability, poor technology and fire risk in terms of their thatched roofs and wooden structures, but were particularly successful in the terms of energy conservation and thermal regulation. While traditional methods and materials are much better suited to the tropical climate than contemporary methods and materials their durability needs to be enhanced. 
More specifically, according to Köppen climate classification, for the tropical charactirization of Honolulu’s climate, the decisions for a more energetically efficient shettle were taken by avoiding the overheating of the interior space. In other words, through all the year, the majority of the external Temperatures overpass the comfort conditions. For this reason, the inhabitants of the Hawaiian islands, with the reasonable choice of the materials, the orientation and the shape of the constructions aimed to reduce the heat gains and increase the heat losses along the year.

Heat transfer

Intelligent site selection and building orientation achieved to eliminate the extremes of heat, cold, humidity, air movement and exposure. However, one of the most significant characteristics of the Hawaiian hale is the thick wall and roof, which usually are not clearly separated because of the great inclination of the latter. Both parts are usually constructed from layered grass, as already mentioned, and this vegetative cover ameliorates climatic problems in many ways. One of the main reasons is temperature variability, since due to their high conductivity a significant reduction in the heat transfer is achieved. Additionally, the porosity of the structure retains the cooling moisture of precipitation, as well as cools and refreshes the heated air by evaporation. In other words, the evaporation of moisture from paved, surfaces spray heads, mulches and foliage provide welcome relief from heat. Last but not least, during the cooler hours of the days, the thick cover with limited fenestration is able to protect the soils and environs from the freezing winds. 

Ventilation and Air changes

Single wall plantation houses used few materials and therefore the natural ventilation was obtained. This contributed not only to the air quality inside the building but also to the temperature, since the air moving across the moist surface of the foliage of the walls made the air cooler. Additionally to the small number of openings, the raised post-and-pier construction kept the interior area cool and fresh during the hot months. 

Solar gains and radial losses

Structural protection was important not only for the heat and the strong winds, but also to avoid the discomfort of solar radiation. The precise design of the Hawaiian hales response to the angles and arches of the sun. Wide roof overhangs and limited fenestration can be distinguished in the settlements of Pacific islands. The vegetative cover is of major importance not only for the insulation of the building, but also for the shading that is necessary to be provided. The high inclination of the roof shades the ground surface and provides sunscreen, shade and shadow to the occupants. Additionally, the good estimation of the openings, allowed also a favored amount and type of light to be received at the favored time. Furthermore, the wide overhangs, especially those over the fenestration, shade the windows from the sun during the overheating summer period, while allows the sun rays to reach the window surfaces and spaces in winter. This can be justified, because mid-day solar altitude angles are much higher in summer months than in winter. In this way, by providing summer sun shading is not necessary to conflict with winter solar heat gain. Lastly, the wide overhangs of the roof minimize also the reflectivity of ground and building surfaces outside windows facing the summer sun.
To sum up, the primitive architecture revealed a commendable level of performance when judged in the light of modern building technologies. All these evidents from the past, addressed nowadays, based on the combination of climate and needs of comfort of the inhabitants,the first roots for a bioclimatic design of the new structures. According to Köppen climate classification, for the tropical charactirization of Honolulu’s climate and for a sustainable and energetically efficient design, the “Watson and Labs matrix” listed below can be followed.