Twin houses

Researchers plan to maintain one house exactly the same over time as a baseline [reference house], while testing advanced technologies by making changes on its twin [test house]. The technique will allow scientists to record precise measures of the cost and energy savings contributed by a wide range of new technologies.

Twin Research Houses

CCHT facilities have been developed in consultation with industry to take the guesswork out of new housing technology. The identical life-sized houses at the site are designed to offer rigorous real world testing of new energy-related products and systems. The houses are extensively wired with computerized monitoring equipment designed to track every aspect of performance.


The houses were built in 1998 to a design submitted by a local builder and are typical in construction, appearance and layout of tract-built houses available on the local housing market. They are identical, and are built to the R-2000 standard - Canada's benchmark for energy efficient house design. They have approximately 210 m2 of livable area, and feature a full basement and a two-car garage.


Side-by-side testing

Monitoring the energy performance of actual houses for a full year has often been considered the most credible way of assessing the energy efficiency of a house design and its energy efficient components. In reality, the results of such experiments were always difficult to interpret, especially if the house had been occupied. From many such attempts, it was found that the occupant lifestyle had as much or more influence on the energy consumption of the house than any individual energy efficient component - thus reducing the credibility of the information provided by the monitoring. If the house were left unoccupied, the mode of operation of the house and its resulting energy budget would not be realistic. The interaction of internal heat gains from energy using appliances and occupant heat gain would be missing from the energy balance.

Monitoring results from occupied houses have also been compared to computer simulations to try to detect whether the energy efficient devices had an impact on the overall energy consumption of the house. Yet predicting the exact performance of a house in a given year in a given climate is probably the most difficult challenge that a computer model can have. For example, models cannot simulate people behaviour realistically. Thus, comparisons of measured and modeled results usually end up informing us more about shortcomings in the model rather than actual performance differences due to energy efficient measures.

The Canadian Centre for Housing Technology has solved these problems in assessing energy efficient equipment and components. The two identical test and reference houses are 'occupied' by electronic controllers that turn on and off appliances, lighting and equipment the way people do. This system of device control is referred to a 'simulated occupancy'.

As originally built and with the simulated occupancy system operating, the test and reference houses have been benchmarked and shown to consume the same amount of energy on any given day. The test house can be modified to assess the impact of an innovative technology on the overall energy and comfort performance of the house. This is assessed by comparing the performance of test house to that of the reference house. By eliminating all other differences in energy performance, including those related to occupancy, the difference resulting from the use of an energy efficient device or control system is observable with considerable accuracy, on a daily basis. After each project, the test house is returned to its original condition and benchmarked against the reference house.

Simulated occupancy

The research houses feature standard sets of major appliances typically found in North American homes.

Kitchen Sink and Kitchen "Humans"

A system based on home automation technology simulates human activity by operating major appliances (stove, dishwashers, washer and dryer), lights, water valves, fans, and a host of other sources simulating typical heat gains. The schedule is typical of activities that would take place in a home with a family of two adults and two children. Electrical consumption is typical for a family of four and hot water draws are set in accordance with ASHRAE standards for sizing hot water heaters.

The heat given off by humans is simulated by two 60 W (2 adults) and two 40 W (2 children) incandescent bulbs at various locations in the house. The schedule can be easily modified to accommodate particular assessment requirements.

Data acquisition system

Electric Meters

The computer that controls the simulated occupancy also monitors energy performance and thermal comfort. In all, 23 meters (water, gas and electricity) and over 250 sensors (thermocouples &relative humidity) provide 12,000 readings every 24 hours.

Gas Meters

Data is overlaid on plans, elevations and sections for viewing. Sensors can be added as needed to expand our monitoring for individual research projects. To view a sample of typical CCHT data see the House Data Virtual Tour.

Weather is monitored by the Institute for Research in Construction at a nearby weather tower on the NRC campus. Collected data includes: solar radiation, wind speed and direction, temperature, humidity, and precipitation.

CHP capabilities

The Test house at the CCHT has been upgraded for testing residential combined heat and power (CHP) systems. The upgrades include a balance of plant (BOP) that stores heat from the CHP and delivers it to space heat and domestic hot water on demand, and a grid connection that meets local utility codes and supplies excess electricity to the grid.

Electrical Modifications in Preparation for CHP systems

The Test house at the CCHT has been upgraded for testing residential combined heat and power (CHP) systems. The upgrades include a balance of plant (BOP) that stores heat from the CHP and delivers it to space heat and domestic hot water on demand, and a grid connection that meets local utility codes and supplies excess electricity to the grid. The BOP is fully instrumented and includes programmable controls. Electrical power to and from the CHP is monitored, and power quality is measured between the CHP, the house and the grid. The facility has been used to test a natural gas fired Stirling engine CHP, and is capable of testing fuel cells.

For more information on the testing of CHP systems at CCHT, please see the following document:

ARCHIVED - Development of Micro Combined Heat and Power Technology Assessment Capability at the Canadian Centre for Housing Technology (PDF format, 1.7 MB)
Bell, M. Swinton, M.C. Entchev, E. Gusdorf, J. Kalbfleisch, W. Marchand, R.G. Szadkowski, F.
pp. 48. 2003-12-08

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