A house is a complex system of different components that interact and determine the performance of the home and the safety and health of the people living there. In order to accomplish net-zero performance such as the Discovery 5 House, the house must be approached as a system. Discovery 5 features four major interdependent parts, each impacting the home's overall performance: the building envelope, the mechanical system, the renewable energy systems and water resource management. When all the parts work together in an optimal way, the reward is a durable, healthy and energy efficient home that people love to live in.

The Discovery 5 House heating system takes advantage of an advanced building envelope and active and passive solar heating to achieve the net-zero standard. To arrive at net-zero, the sum of all electrical and thermal energy used must equal what is supplied by renewable resources over the course of one year.

But Discovery 5 goes beyond net-zero building envelope standards that typically relate to energy efficiency alone. Architectural ecology defines a broader scope of sustainable building practice: the Discovery 5 house is working towards a net-zero water standard by maximizing its potential for rainwater capture, collection and storage.

Architectural ecology features like living walls and green roofs are used in the building industry to help with storm water retention, climate control, and insulation while adding beauty to the environment. It's easier than you might imagine to inject a little green life onto the surfaces of your home. Adding a green roof increases a home's efficiency and aesthetic value as well as helping to decrease the urban heat island effect in your neighbourhood from sun radiating off paved and non-porous surfaces.

The Discovery 5 house has incorporated a small green roof plot and rainwater trough as amenity features to the master bedroom and backyard.

The Discovery 5's green roof has been designed by SAIT Polytechnic to test the rainwater pre-filtration capacity of specially designed green roofs. This could positively affect Discovery 5's downstream rainwater harvesting infrastructure and associated costs and maintenance while improving rainwater quality towards a goal of potable consumption. Pre-filtering raw rainwater is done to remove sediments, soluble pollutants and organics before the rainwater travels to the cistern storage tank. Improved water quality will reduce the frequency of storage tank cleanouts, wear and tear on the mechanical, and may decrease the complexity and components of the overall system.

Living walls or green walls are self sufficient vertical gardens that are attached to the exterior or interior of a building. The plants receive rainwater and nutrients from the cistern and are plumbed directly to the vertical support instead of from the municipal water supply. Most green walls use some type of grid planter system using a frame, cells and irrigation channels.

The installation of "enhanced" ecological features inside structures is becoming more common within the green building industry. Living walls offer a natural, lush, serene green alternative improving indoor air quality and reducing cooling requirements during the summer months. Quite aside from their aesthetic attributes, plants are known to remove harmful environmental toxins found in building interiors.

The Discovery 5 house integrates harvested rainwater and energy efficient lighting with the modular DIRTT Breathe™ Living Wall system (PDF).

The Discovery 5 House has a solar photovoltaic system on both the roof and garage that will provide electricity to offset the home's electrical demands. Referred to as a Grid Tied Solar Electric System, Discovery 5 is tied into the municipal utility grid. The Discovery 5 photovoltaic system compares flat vs rack mounted modules on the main roof, with a simple 22.5 degree garage roof system. When any of the home's electricity generation is not being used in the home, the excess electricity is fed back into the utility grid.

House orientation and roof slope play an important role in the effectiveness of Solar power as an energy source for a house. The Discovery 5 House presented multiple opportunities, challenges and barriers as a Net-Zero infill home. Primarily, the home's narrow side is facing south reducing passive gains through windows and due to its contemporary design, the roof's profile orientation and slope are far from the solar ideal for electrical generation. In addition, although the garage is ideally suited for slope and south orientation, the solar chimney and neighbouring trees create shading patterns on both the main house roof and garage. SAIT will continue to monitor the three solar photovoltaic systems to compare performance, energy generation and cost of installed systems to optimize urban infill solar installation parameters.

SAIT's research design for the solar array recognizes these multiple constraints and consequently will compare two different module racking types. The design considered performance factors of shading, angled racking, spacing the modules further apart for shading, winter snow coverage, and of course costs of the system and installation. Crystaline Silicon technology has been chosen as it has a higher level of efficiency or production output. Half of the Discovery 5 House solar modules lay flat on the roof, reducing racking and the cost of installation while offsetting any performance losses with an increased number of modules. The other half of the modules on the main roof have been racked or angled with a southern orientation, but due to shading from each rack, fewer modules have been installed.

These two technologies tested in the same environment could provide new information for future installations as well as performance data using solar photovoltaic panels on flat residential roofs.

Building Integrated Solar Thermal components are used most widely for heating water and space heating. The Discovery 5 House utilizes a passive solar chimney and west facing windows to absorb heat energy from the west setting sun. Cold, pressurized city water is plumbed to an active solar panel inside the home's solar chimney, preheating the water before continuing to the domestic hot water tank. In addition, solar thermal energy is being used to offset heating demands.

The Discovery 5 House heating system takes advantage of an advanced building envelope and active and passive solar heating to achieve the Net Zero standard.

To meet the heating demands of Discovery 5, a five zone photovoltaic supplemented electric baseboard heating provides space heating for the second floor and solar thermal augmented radiant infloor heating warms the basement and main floors. Passive solar gains from the main floor south facing windows are absorbed into the concrete floor and recirculated throughout the main floor before the boiler turns on. This reduces the heat load from the boiler while ensuring adequate heat distribution from the solar gains through minimal electrical pump usage. Similarly, in the summer passive cooling from the basement can be pumped throughout the radiant floors to cool the home on hot summer days.

An active, high efficiency Heat Recovery Ventilator distributes continous fresh air and redistributes solar heat gains throughout the house. Finally a Solar Chimney naturally ventilates the house with operable end windows and automated controls.

The Discovery House has been designed to include progressive plumbing measures which focus on water conservation and drainwater heat recovery. The Discovery 5 House is working towards a net-zero water standard by maximizing its potential for rainwater capture, collection and storage.

Rainwater harvesting for reuse purposes is one way to conserve fresh water supplies and to utilize less municipally distributed potable water.

The Discovery 5 House has incorporated a large rainwater harvesting system which will collect rainfall from approximately 145m2 of roof area (house and garage). The harvested rainwater will be directed to a below ground cast-in-place cistern that will store over 14,000 litres of rainwater. Discovery 5 utilizes rainwater to flush toilets, for cold water laundry, outdoor hose bibs and irrigation of the green roof, living wall and landscaping. Additionally the system acts as an exemplery tool for infill neighbourhood storm water management as it reduces site water runoff and the capacity required of municipal storm water systems.

SAIT is sampling and testing water at different locations within the rainwater harvesting system to compare the water quality of rainwater, the filtration capability of the green roof , a typical stand-pipe first-flush method in addition to monitoring of the green roof filtered rainwater quality before its end uses.

The plumbing layout in the Discovery 5 contains the following attributes:

• Rainwater Harvesting utilized for toilet flushing, cold water laundry and outdoor hose bibs
• Purple pipe distribution of stored rainwater as required by CSA Standard for "non-poptable water systems"
• Greywater plumbed separately for drainwater heat recovery and potential future treatment and recycling of greywater
• Hot water is pre-heated by a Solar Chimney and Greywater Heat Recovery Unit, with an off-shoot of preheated water as the cold distribution to the second floor showers
• Green roof test plots are utilized as rainwater pre-filters and rainwater is also utilized to irrigate and establish green roofs
• Living wall will be irrigated with unfiltered rainwater
• 14,000 litre Cistern for annual rainwater provision