Final Report: Deployable Homes Following Natural Disasters

EPA Grant Number: SU833191
Title: Deployable Homes Following Natural Disasters
Investigators: Schaad, David , Alvarez, Byron , Beardsley, Samantha , Brasier, Chris , Foster, Annie , Kielb, Robert , Liddle, Scott , Marios, Tsakiris Iakovos , Martin, Andrew , McDaniel, Devin , Millar, Nicholas , Nektarios, Moraitis , Remi, Vives , Roland, Leroux , Tierney, Jennifer , Zernin, Fischer
Institution: Duke University , KTH - Royal Institute of Technology
EPA Project Officer: Nolt-Helms, Cynthia
Phase: I
Project Period: September 1, 2006 through May 30, 2007
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2006) RFA Text |  Recipients Lists
Research Category: P3 Challenge Area - Built Environment , Pollution Prevention/Sustainable Development , P3 Awards , Sustainability

Objective:

The project goal was to develop housing designs for development, construction, or rehabilitation following a natural disaster. There are two options to choose from as a basic framework to accomplish this goal: rapid rebuilding or transitional housing. Initially rapid rebuilding was explored as a potential solution to the rebuilding issues. However, transitional housing was primarily investigated in this project because it involves rapid deployment, immediate livability, and stricter budgeting, while rapid rebuilding is much more difficult to implement due to the various housing situations it must accommodate (houses, apartments, etc.) and its contribution to cultural uniformity (cookie-cutter designs).

The objective was to design a model of transitional housing that will arrive at the site of disaster within a few days and can immediately support the population. In the aftermath of Katrina, FEMA trailers were unable to meet the basic services that would have made them livable and therefore sat abandoned. In this project, FEMA trailers were chosen as the main structural element of the housing units since they are already available in large numbers, thus this project investigated the retrofitting of these trailers with appropriate technologies. The trailer must be self-sufficient, sustainable, adaptable, inexpensive, and have high living standards. Finally, the trailer has been designed to serve as an example of efficiency without sacrifice.

Each system involved in the functioning of the trailer has its own specific objectives. The appliances to be utilized in the trailer were to be compact, meet energy star standards and adhere to reduced water use while providing the same comfort as regular devices. Heating and cooling is often the largest energy user in a residential unit and thus must be designed very efficiently to reduce loads on the system. Specifically, the heating system should maintain the trailer at 68 degrees and 50% humidity during periods of heating, the ventilation system should provide at minimum 10 cubic feet per minute (cfm)/person, and the cooling system should maintain the temperature of the trailer at 75 degrees and 50% humidity during periods of cooling. The system should provide stand-alone power, as well as have the capability to be connected to the grid. Costs should be weighted toward capital investment, rather than toward operation and maintenance, to relieve the users of some cost burden and place more of the burden on FEMA. Due to low availability of water when the trailer is not connected to any water lines, a water filtration system is required to recycle water in non-potable applications. It will also need to be energy and cost efficient to conform to the rest of the project goals. A water heating system was also implemented to heat water for applications in the dishwasher, shower, sinks, etc.; the objective of water heating was to heat water with as little energy as possible.

Summary/Accomplishments (Outputs/Outcomes):

The project team developed a sustainable design for a deployable shelter incorporating many aspects of energy efficiency and renewable and/or reusable resources. The selected electrical appliances (and their specifications) to be used in the prototype trailer are presented below:

Table 1.

Also, it was found that the maximum cooling the trailer is expected to need is 1.41 tons. The maximum heating needed will be approximately 0.74 ton. Since a compact unit will be needed to supply this heating and cooling, a heat pump was chosen as the best possible method. Heat pumps have the ability to both heat and cool an area. They are energy-star rated for their efficiency in both heating and cooling. The TREAD trailer model will need to have an HSPF3 greater than 8.2 (preferably 10) and a SEER4 greater than 14 (preferably 18). Solar panels with batteries for energy storage were chosen as the optimum way to power the trailer. A diesel generator that runs off of biodiesel fuel was chosen as a backup system for power generation. The final sizing of the solar panel array is a 2000-watt system with a 3.5kW generator.

The water filtration unit designed for use in the trailers consists of a coarse screen, coagulation/flocculation, an upflow coarse sand filter, a downflow fine sand filter, an upflow GAC filter and inline chlorination. The entire system fits beneath the trailer, thus having no space requirement, minimizes cost by using inexpensive filter media and minimizes water waste by forgoing backwashing in favor of disposing of the filter media at the end of the filter life. Energy requirements are also minimal as the only energy input is for the pump, which must only generate an estimated 7 feet of head (assuming 6 in. diameter and 1 foot bed depths for all three filters).

The water heating system decided upon was a tankless water heater for heating water for the kitchen and bathroom faucets and a solar water heating unit for heating grey water for reuse. The tankless water heater chosen is a 3.5kW model that creates a temperature differential of 50°F in the bathroom faucet and 25°F in the kitchen faucet. The solar water heating will be a unit that can provide approximately 34,000 BTU on a clear day.

Conclusions:

The project design has successfully developed a model for a sustainable, deployable shelter for survivors of natural disasters. To facilitate this, appliances used in the shelter were selected to reduce energy needs, water usage and cost. Heating and cooling with the same unit, a heat pump, was decided to be the best option due to space constraints. Heat pumps that well exceed energy star standards are available that will reduce power inputs, which are further reduced by the implementation of a programmable thermostat. Solar panels were found to be the only viable option as the main components of the power system, with a biodiesel generator as backup. The water filtration unit to be implemented combines unit processes that filter water to EPA standards for reuse while conserving energy and water. Lastly, the water heating system chosen was a tankless water heater for faucets and a solar water heating unit for grey water. This design is energy efficient as well. By conserving energy and using alternative power sources (solar panels) the trailer also reduces CO2 emissions significantly over the course of its use.

Proposed Phase II Objectives and Strategies: The final goal of Phase II is to build a prototype trailer in conjunction with community partners in the gulf coast. A number of steps must be taken for this to be possible. First, the water recycling system must be tested to find exact specifications. Additionally, real-life testing of the PV array, solar water heating, and appliances must be conducted to better establish exact energy production and usage and water heating capabilities. Finally, a few more design additions are going to be explored. This will primarily focus on adding wings to the roof of the trailer and adding a rain water catchment system.

Based on the analysis by the students, with the Phase II grant award, and an additional year of work, a fully retrofitted trailer that is ready for human habitation could be created. It will include all the technologies explained in this document and be almost self-contained for use following natural disasters. The trailer will then be submitted for a holistic review for its applicability in U.S. disaster situations. Following trailer completion, it is of interest to the team to summarize the technologies used that are applicable to residential situations. The trailer is an example of the possibilities of residential units in the 21st century in terms of sustainability and greenness. Its mobility allows the trailer to be viewed by numerous communities and become a living example for many who want to live more sustainably but do not know where to get started.

References:

  1. based on average appliance uses from http://www.cityofames.org/SmartEnergy/ Exit and 1.325 lbs of CO2 per kWh
  2. Using average price of $0.096/kWh
  3. HSPF: A heat pump's estimated seasonal heating output (in BTUs) divided by the amount of power that it consumes (in Watts).
  4. SEER: A measure of the efficiency of an air conditioning unit, SEER is the ratio of cooling output divided by power consumption

Supplemental Keywords:

sustainable design, transitional housing, post-disaster, green building, disaster response, sustainable construction, environmentally conscious manufacturing,, RFA, Scientific Discipline, Sustainable Industry/Business, Sustainable Environment, Technology for Sustainable Environment, Environmental Engineering, Hurricane Katrina, sustainable development, alternative building technology, environmental conscious construction, green building design, natural disasters, alternative infrastructure design, architecture, Design for Environment