Updated Proposal

2010 YWCA/CHBA Green Dream Home Rendering by Dale Parkes

Introduction

"Residential and commercial buildings contribute directly to Canada's greenhouse gas emissions through the combustion of fossil fuels to meet water and space-heating requirements. In addition, the residential and commercial sectors contribute, indirectly through electrical consumption. The total represents approximately 25% of Canada's overall greenhouse gas emissions."-- Canada, 1995, National Action Program on Climate Change.

Not only do buildings contribute greatly to global warming but as energy costs continue to rise, our current methods of living will become unaffordable. To decrease these costs, it is becoming increasingly more financially viable to find alternative building methods. Increased insulation and a more effective building envelope can significantly reduce energy demands.

Summary Statement

How does an R44 Insulated Concrete Form (ICF) wall perform with respect to thermal mass, r-value, and building envelope when compared to traditional ICF walls and wood frame construction based on actual performance, theoretical performance, and manufacturer’s expectations?

Purpose

To explore the feasibility and performance of an alternative method of construction I plan to test the performance of the wall assembly of the 2010 YWCA/CHBA Green Dream Home (Part of the CMHC EQuilibrium initiative). This house, designed by myself, uses a Logix XRV ICF that has 8 inches of insulation on the exterior of the wall compared to regular ICFs that have 2.75 inches of insulation on the exterior. Concrete normally has a thermal mass that acts as a heat storage system and can serve to regulate temperature. This ‘mass effect’ may or may not contribute to the wall performance since ICFs also have a layer of insulation on the inside of the concrete. There is very little data regarding the performance of this wall system and professional opinions seem to vary on the topic. It would be valuable to quantify the performance and either substantiate or rebuff these opinions.

Goals and Objectives

The objectives of this study are to assess:
1) how and when heat dissipates and transfers through this wall system with regard to time of day and time of year,
2) the existence of a thermal mass effect with regard to cooling loads,
3) if a thermal mass effect is more accessible in this variation of ICF block due to an uneven distribution of insulation,
4)how a thermal mass effect, if one is present, will improve the overall thermal performance of the building, and
5)the actual and effective thermal resistance of the XRV ICF panel and the overall thermal performance of the wall system.

Methodology and Analytical Approach

In order to measure the temperature gradient of the wall it will be necessary to construct an ICF temperature gradient probe using PVC pipe and LM35 Precision Centigrade Temperature sensors (or similar semi conductor). Once sensors are installed in the probe, the pipe air voids will be filled with spray insulation. The pipe will be filled with spray insulation. The wall will be measured in four places (see wall section) and in four locations. The sensors will be doubled at each location to account for error. The sensors will be set to record a measurement at a set interval. Data will either be acquired through a hobo logger data acquisition device (2 per location) or be routed to a central data acquisition hardware device interfaced to a computer running LabView software (National Instrument). The probes will be installed in February while the walls are still unfinished. The method used for theoretical calculations will be the ASHRAE CLTD method.



Previous Studies and Related Information

Few studies have been performed on ICF wall systems and with varying results. The information available is contradictory. Some studies suggest that “the only limitation of ICF is the ability to recover heat from thermal mass” and that it “does provide buffering during swings in temperature” (Enermodal, 2006). While the ICF association suggests that “the ICF concrete core offers the characteristic thermal mass qualities of heat absorption and thermal lag” and serves to “moderate indoor temperature” (ICFA, 2008). But it seems, in general, that little is known, and even less about this particular type of ICF product or anything with a comparable insulation value. This model of ICF arrived on the marketplace in 2009. As the first of its kind, even less is known about the potential performance of this product.

Plans for Dissemination of Work

There are many parties interested in the results of this study and possible publication. Members of both the Canadian Home Builder’s Association and Canada Mortgage and Housing Corp. have expressed interest in the topic and offered assistance. There will be a BLOG written as part of a class assignment. The manufacture of the ICF blocks may desire some involvement in the study. There would be presentation opportunities in conjunction with CMHC’s EQuilibrium Home Demonstration initiative as well as opportunity to present at TRU related functions. In addition to the above mentioned venues, when I begin a career as a building designer and technologist I would incorporate this information in future building designs.