Driver Trett Digest Issue 26 - Flipbook - Page 24
their commitment to purchasing renewable energy.
Microsoft has committed to a 100 per cent supply
of renewable energy by 2025, meaning they will
have power purchase agreements for green energy
contracted for 100 per cent of carbon-emitting
electricity consumed by all of their buildings and
campuses.
This is an essential step in operating more sustainably,
but there are some limitations to this:
1. In most locations, there is a limited amount of
renewable energy available.
2. If the buildings are connected to the grid, the actual
electricity being consumed will be whatever the grid
energy mix is.
On-site renewable generation is rare for several
reasons:
1. Cost – capex and opex.
2. Skills and expertise. Design, operation and
maintenance of power generation requires different
expertise and adds complexity.
3. Space limitations – generation plant takes up
valuable real estate. Covering the roof with solar
panels may only provide a fraction of the total energy
requirements.
WATER USAGE
Many buildings have reduced the energy consumption
of their cooling systems by using adiabatic,
evaporative cooling, which uses the cooling effect
of water evaporating rather than electricitypowered refrigeration. This results in increased
water consumption on site. This is not desirable in
locations that suffer from water shortages / seasonal
droughts. The net water usage may be more, but the
overall environmental impact may still be less when
considering the reduced environmental impact of using
less electricity. A life cycle assessment (LCA) is required
to analyse the trade-offs.
HEAT RECOVERY
Reusing waste heat is one way that buildings try to
improve their environmental credentials. Rather
than rejecting heat from cooling processes to the
atmosphere, this can be captured and used by others
(residential buildings, greenhouses, swimming pools),
for example via a heat network, thereby reducing their
energy consumption for heating.
There are a few barriers to wider adoption of waste
heat reuse:
1. Although there may be a large amount of heat
available, it is usually relatively low-grade heat e.g.,
air