Three renewable energy systems - solar water heating, solar space heating, and solar photovoltaity - are described that can be used in multi-residential buildings like condominiums. Solar water heating uses solar collectors to pre-heat water and reduce energy costs. Solar space heating uses solar panels to pre-heat air entering a building. Solar photovoltaics generate electricity from sunlight that can be used or sold back to the electric grid. These renewable systems can provide significant savings on utility bills for condo buildings while reducing environmental impacts.

1. 26 CONDOBUSINESS | Part of the REMI Network26 CONDOBUSINESS | Part of the REMI Network
Condo corporations must pay
to heat, light and air-condition
common spaces such as the lobby,
hallways, garage, exterior parking lot and children’s
playgrounds. Individual condo owners pay their share of these costs through their
condo fees, and energy costs are only going to continue rising.
BY DR. IJAZ A. RAUF
Three renewable energy systems with
applications in condos
TECHNOLOGY

2. www.REMInetwork.com | November 2016 27
That’s because the pressure on existing networks is increasing.
Global energy demand is expected to more than double by
the year 2050, even with aggressive conservation and energy
efficiency measures.
Incremental improvements in existing energy networks will
not be adequate to supply this demand in a sustainable way.
This, coupled with the threat of climate change, has triggered a
widespread interest in renewable energy.
Energy harvested from natural resources that can
be replenished naturally within a human being’s lifespan is
considered to be renewable. It comes in many forms, including
hydro energy, solar energy (heat and light), wind, biomass,
geothermal and ocean energy.
The sun is the source of all forms of renewable energy, except
for geothermal and ocean energy. What follows is an overview of
three renewable energy technologies that can be used in multi-
residential buildings.
Solar water heating
There are many ways in which a Solar Water
Heating System can be installed. Figure 1 shows
a simple schematic of a solar domestic water
heating system. Cold heating fluid is run through
the collectors. Then, the hot fluid is used to
warm up the potable cold water intake. The gas or electric based
water heating system thus gets pre-heated water, reducing gas and
electricity consumption.
The federal and provincial governments strongly support solar
water heating system installations for their environmental benefits
as well as for reducing energy use. Incentives of up to 50 per cent of
the total cost of the project are available to commercial and industrial
corporations, such as condominiums, for installing solar water heating
systems.
TECHNOLOGY
Solar space heating
Figure 2 show a schematic of a solar air heating
system. A perforated heat-absorbing material is
installed on the exterior wall of the building with
a small gap. The air trapped between the solar
wall and exterior wall of the building gets heated
and rises. Through the perforations, the outside
fresh air fills the vacuum created by the rising hot air.
Thus, the furnace gets pre-heated air and should work less to heat
the building. This helps reduce the cost of space heating by up to 50
per cent as the space heating system pre-heats the air (30 degrees
Celsius or more compared to fresh outside air). Incentives of up to 50
per cent of total project costs are available in Ontario for solar space
heating projects for businesses.
Solar electricity
Solar electricity is one of the fastest-growing
energy technologies worldwide, rising more than
42 per cent, per year, over the past 10 years.
Both the federal and provincial governments
strongly support solar photovoltaic or ‘PV.’
Figure 3 shows a schematic of the way a
grid-tied solar PV system works to generate electricity silently
and without any moving parts. Visible light from the sun falls on
the solar arrays, generating direct current (DC) electricity. The DC
electricity is converted into an alternating current (AC) household
120 volts by an inverter. This AC electricity is fed into the electric
meter through a circuit breaker panel. This electricity then can be
consumed in the building to run the lights and appliances or fed
into the grid, or both.
At night and during the cloudy weather, the solar system’s
output drops or stops; however, the building can get the
electricity it needs directly from the grid. With the roll out of
smart metering systems and time of use (TOU) electricity rates,
the cost of electricity from the grid is 220 per cent higher during
the day compared to its cost at night. A solar system produces
the most electricity when it is most expensive from the grid.
Cold Water
Hot Water
Supply Cold
Water
Preheated Water
Water for
Household usage
Heat Exchanger
Solar Collectors
Figure 1: Schematic of complete solar domestic water heating system
Figure 2: Schematic of the way a solar air heating system works
Figure 2: Schema?c of the func?oning of a Solar Air Hea?ng System

3. 28 CONDOBUSINESS | Part of the REMI Network
Inverter
DC
AC
Main Panel
Generator
Meter
Utility MeterSun
AC
AC
AC
AC
Figure 3: Schema?c of the func?oning of a Grid-Tied Solar Photovoltaic System
Ontario’s Feed-in Tariff Program allows one to sell all the solar
electricity to the grid at a premium rate for grid-tied systems over
a contract of 20 years. Combined revenue for the solar PV system
output depends on the nameplate rating of the system. This revenue
helps pay off the initial cost of the system much faster (roughly within
five to six years) and provides a source of revenue for the remainder
of the contract.
Installing solar water heating, solar space heating and solar
electric systems can reduce lighting, heating and air-conditioning
bills significantly. Figure 4 shows a multi-family, high-rise building
that installed all the three technologies. They generated more
than $100,000 in annual savings on electricity and gas bills, even
though the building had limited space in which to install renewable
technologies.
And, for the most part, renewable energy is free — after covering
the cost of initial installation. With installation costs dropping, energy
prices rising (for both gas and electricity) and time of use rates
in place, renewable energy makes a lot of economic as well as
environmental sense. It will also take on increasing importance as the
provincial and federal governments step up their efforts to combat
climate change.
Figure 3: Schematic of the functioning of a grid-tied solar photovoltaic system
To meet its environmental targets, the province of Ontario no
longer uses coal to generate electricity as of the end of 2014. The
province’s goals are to reduce greenhouse gas (GHG) emissions to 15
per cent below 1990 levels by 2020, and to reduce emissions to 80
per cent below 1990 levels by 2050.
As per Ontario’s environmental commissioner’s report,
the building sector alone represents 30 per cent of the total
GHG emissions for the province. What’s more, this sector
has seen steady growth and consequent increase in GHG
emissions of 17 per cent from 1993 to 2013.
The federal government also recently announced that, as
of January 2018, everyone will have to pay a new carbon tax
at an initial rate of $10/tonne of carbon dioxide (CO2), rising
to $50/tonne of CO2 in 2022.
Dr. Ijaz Rauf is a solar energy expert. He obtained a Ph.D. in
physics from Cambridge University in England. He is currently
the president and CEO at SolarGrid Energy Inc. and an adjunct
professor in the Department of Physics and Astronomy,
York University. He can be reached via e-mail at irauf@
solargridenergy.ca or phone at (888)743-4621.
Figure 4: A multi-family high-rise building featuring solar water heating, solar space heating and solar photovoltaic technologies
TECHNOLOGY