EcoHouse Research

Fabio Micoli (2012, MEng)

 

The objective of this project is to perform a related in-depth study on a specific design issue: the failure of the current UTPMP design to provide adequate levels of thermal comfort to its occupants. The primary concern of the project was to specifically contextualise the design problem and field research was conducted in Quito (Ecuador), where the Eco-House Initiative is developing its first research.

 

Preliminary predictions and modelling were performed, outlining the governing factors of the thermal performance of this particular building envelope: the general behaviour as a light-weight structure, the absence of any thermal mass, and the consequent large daily fluctuations (up to 11 °C), that match at every point in time the external temperature. Integrating these data with the peculiar weather data available for Quito, the author could run yearly simulations using the software package IES VE to simulate the house response. The lack of many calibration parameters for the constructed model determined the vital importance of the collection of primary data in Quito (December 2011). Measurements taken on four different house revealed real profiles of temperature and humidity over a period of five days and additional measurements accompanied by interviews enabled the researcher to identify the key problems to be tackled. The two main problems identified were the heavy daily overheating due to the strong solar radiation and the low temperatures accompanied by high humidities at night. This confirmed the predictions formulated and allowed to collect the necessary data for the calibration of the model.

 

The next stage consisted in the formulation of a design solution to the problem outlined: three different proposals resolving the problem of adequate provision of thermal comfort at increasing levels of complexity and efficacy are presented. The approach to the design solutions is based on the context observed and wants to emphasise the differences with standard design carried out in the developed world: a series of ’soft’ constraints imposed by the ’strengths’ of the current design were identified and allowed to vary only in the presence of a quantifiable improvement in thermal comfort.This has enabled a more focused research, achieving results of practical value. The three design solutions outlined are the following:

 

- ’Usable spaces that do not overheat’: a proper ventilation strategy is introduced by means of an openable roof combined with low-level openings. In this way the day time habitability of the house is greatly enhanced and the peaks temperature maintained within 26°C. The overall increase in cost is 6.8%. - ’Divide and insulate’: this more elaborate proposal introduces a proper space division which leads to an expansion of the house. The night time thermal discomfort is resolved with straw panel insulation, increasing the inside temperature by 4-5°C. The general strategy for the living-room benefits from the findings of the first proposal. The overall increase in cost is 49.6%.

- ’Speculations on solar passive design’: this last proposal aims at exploring the maximum potential of delivering thermal comfort of this low-technology building envelope, introducing a water roof and a system for internal air circulation; the increase in temperature of a further 1-2°C can be regulated by the occupants at their own discretion. The additional cost of the whole proposal is 55% of the original one.

 

The implications of each proposal are discussed and the conclusion of the study is that the cost of solving the problem represented by the lack of thermal comfort does not justify by itself the transition to more permanent houses. These results combined with further research aimed at enhancing the durability and structural reliability of the house might be a more effective answer for the context analysed.