1. Towards near zero energy buildings – challenges
and solutions
April 2015
2. What is BIPV?
29/04/15 SES SIG BIPV workshop 2
Definition from CENELEC BIPV specification (prEN 50583)
‘Photovoltaic modules are considered to be building-integrated, if the PV modules form a construction
product providing a function as defined in the European Construction Product Regulation CPR 305/2011.
Thus the BIPV module is a prerequisite for the integrity of the building’s functionality. If the integrated
PV module is dismounted (in the case of structurally bonded modules, dismounting includes the adjacent
construction product), the PV module would have to be replaced by an appropriate construction product.’
Different
mounting
categories of
BIPV
Other pre-standards activities:
• ISO DIS 18178 Glass in building — Laminated solar photovoltaic glass
• IEC 62980 Ed.1 Photovoltaic modules for building curtain wall applications
4. Perovskite represents the most significant breakthrough in solar
technology since the 1970s
Increasing photovoltaic cell efficiency is today’s
#1 lever for further cost reductions of solar power…
…but the efficiency of market-dominating crystalline
silicon and established thin-film technology has
plateaued
1970 1980 1990 2000 2010 2020
0%
10%
20%
30%
20.1%
perovskites
silicon
thin-film
(CdTe, CIGS)
(no further
progress)
Photovoltaic cell efficiency records
Perovskite takes solar technology to a whole new
level :
• Extremely fast progress in R&D demonstrates
game-changing potential
• Theoretical maximum (>30%) far exceeds silicon
for single junction cell
• Uses abundant, inexpensive materials, with a
simple cell structure, low wastage and low
manufacturing cost
• Printed as a second layer on top of standard PV
cells to increase absorption and efficiency
SES SIG BIPV workshop 429/04/15
5. Target markets worth $110bn annually, and growing quickly
Tandem boost to existing silicon PV ($100bn market)
short-term launch,
low-capital,
mass market
BIPV– Building Integrated PV ($10bn market)
mid-term,
high-margin,
niche market to begin with
1
2
Future
stand-alone
perovskite
solution
SES SIG BIPV workshop 529/04/15
7. Drivers for near zero energy buildings
The climate and energy package is a set of binding
legislation which aims to ensure the European
Union meets its ambitious climate and energy
targets for 2020.
These targets, known as the "20-20-20" targets, set
three key objectives for 2020:
• A 20% reduction in EU greenhouse gas
emissions from 1990 levels;
• Raising the share of EU energy consumption
produced from renewable resources to 20%;
• A 20% improvement in the EU's energy
efficiency.
The Energy Performance of Buildings Directive
2010/31/EU (EPBD recast) is the main legislative
instrument driving ‘Nearly Zero-Energy Buildings’.
According to Article 9 of the Directive: “1. Member
States shall ensure that:
• by 31 December 2020, all new buildings are
nearly zero-energy buildings; and
• after 31 December 2018, new buildings
occupied and owned by public authorities are
nearly zero-energy buildings.”
29/04/15 SES SIG BIPV workshop 7
EU climate change targets and the Energy Performance of Buildings Directive
EU 2020 targets driving EPBD
8. fabric energy efficiency
efficient heating and
cooling
Carbon
Compliance
Zero
Carbon
on-site
renewables
allowable
solutions
Energy hierarchy- Encouraging the right behaviour
Focus on fabric first
Then heating and cooling
Then renewables can really
contribute to energy reduction
Don’t forget energy efficiency
2020 CO2 emission reduction
targets only possible if
renewables contribute more,
and/or window to wall ratio
reduces
29/04/15 SES SIG BIPV workshop 8
Adapted from Zero Carbon Hub’s hierarchy triangle
As targets tighten,
diminishing returns here
Hierarchy underpinned by energy efficiency
9. Extra challenges for BIPV in the architectural world
First and foremost we are an
architectural product
• Aesthetics
• Performance
• Lifetime
We need to fit into the
construction industry value chain
• Which means we cannot add
lots of extra steps to install
BIPV products
• BIPV IGUs replacements
must follow industry norms
29/04/15 SES SIG BIPV workshop 9
We have to have products that
are flexible in size
• Windows are typically 1.5m
wide, height from 2.75m up to
4m
• Some facades are now using
double width and height
glazing 3m x 6m
If we do not meet this,
we have no BIPV
product
Know your customer
and target market
Product flexibility
10. Opportunities for BIPV versus standard PV
29/04/15 SES SIG BIPV workshop 10
Relative contribution in CO2 emissions reduction with and without BIPV glazing
heating & cooling
49.5%49.5%
fabric performance
Today
on-site renewables
~1%
Standard PV
For tall buildings
aesthetic look of
standard PV limits
application, other
renewables often
not an option
With
Oxford PV
33%33% 33%
Now means more
flexibility on fabric
performance and
heating/cooling
design
Note: Savings relative to Part L
11. Why BIPV can make a difference
20 Fenchurch Street
• Regulated load 6,477 MWh/yr
• Façade area ~ 34,000 m2
• Standard PV <500 m2
52-54 Lime Street*
• Regulated load 1,600 MWh/yr
• Façade area ~ 26,000 m2
• Standard PV <200 m2
29/04/15 SES SIG BIPV workshop 11
Vertical solar farms
20 Fenchurch Street
2.3 MWp
1,180 MWh/yr
606 tCO2/yr saving
Leadenhall Building
2.1 MWp
1,001 MWh/yr
499 tCO2/yr saving
Vision &
spandrel
Vision only
Vision &
spandrel
52-42 Lime Street
2.1 MWp
940 MWh/yr
451 tCO2/yr saving
* The Scalpel is built to newer building regulations & following energy hierarchy
Vision: 6%, spandrels: 15%
Building data from publicly available
sources
12. Impact of differing vision and spandrel ratios
29/04/15 SES SIG BIPV workshop 12
Example of the Leadenhall Building
• Spandrels alone reduce emissions annually by 350-500 tonnes CO2
• Ratio does not need to compromise architectural intent (if thought about early enough in design concept)
• Additionally could offset pressure to reduce window to wall ratio
Leadenhall
Building
Leadenhall
Building
Leadenhall
Building
Glass vision:spandrel ratio Vision only 75:25 60:40
Installed power (MWp) 2,099 2,888 3,361
Energy generation (MWh/yr) 1,001 1,474 1,721
Building energy saving (%) 14% 21% 25%
Building CO2 saving (tonnes
CO2/yr)
499 754 864
Building CO2 saving (%) 15% 23% 26%
Just under 50%
generation from
spandrels
Just over 60%
generation from
spandrels
NB: Saving relative to Part L notional building
13. Balance of System (BOS) Steering Group
We did not have the answers- so
we asked for help:
• What mitigation is needed to
address challenges?
• Output: a document available
to anyone
We are now involved PV
standardisation (member for IEC
TC 82)
Special thanks to Rick Wheal
of ARUP for suggesting to set up
a SIG
Practically addressing BIPV at scale
29/04/15 SES SIG BIPV workshop 13
14. Oxford PV perovskite facts in a slide
SES SIG BIPV workshop 1429/04/15
To generate 1MW
takes <20 litres
The Shard would
require 66 litres
UK PV installed
capacity (5GW)
~100,000 litres
World PV
forecast for 2015
(53GW)
~1,000,000 litres
Or a water cooler
bottle
Or a tank of fuel
Or just less than
a rail tanker
Or an Olympic
swimming pool
half filled
