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Using future weather data for building design
Organisations: Manchester University / University of Bath / Napier University,
Northumbria University / Sheffield University / Met Office
Case study focus
Design and operation of buildings / Heating & cooling requirements
This case study provides an overview of the coordinated research program
COPSE (COincident Probabilistic climate change weather data for a Sustainable
built Environment) which took place between 2008 and 2011.
Building designers commonly model the thermal performance of proposed
designs: first to estimate annual energy consumption and secondly to provide
information on internal environmental conditions during periods of hot weather.
Typically this is done using computer modelling based on a typical and
exceptionally warm year of hourly weather observations.
The aim of the project was to develop methodologies to assess building designs
in future climates. In particular it focuses on maintaining comfort levels while
minimising energy use.
What was it used for?
UKCP09 Weather Generator has the potential to provide high resolution data for
projects but it is not produced in a form that is directly suitable for assessing
climate change impacts on buildings design and operation.
The project is an example of how academic researchers have harnessed UKCP09
output to develop bespoke information for use by designers, building owners
engineers and decision makers. Ultimately the research findings have
contributed to specific guidance, which have already been in real-world design
assessments.
Which UKCP09 products were used?
The Weather Generator
Approach and how UKCP09 was used
The UKCP09 Weather Generator was used in four keys areas of COPSE:
1. The development of ‘future weather files’ for use in modelling building
performance. These are based on output from the UKCP09 weather
generator.
2. The weather scenarios (i.e. future weather files) were used to model the
future cooling and heating requirements for four example buildings – an
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office building, a primary school, a hospital and a residential care home in different geographic locations around the UK.
3. Researchers were able to test example thermal comfort standards for
individual buildings and the implications these have for energy use for
cooling across a range of possible future climates.
4. Assessments of future national energy requirements for space heating
were made.
1. Developing future weather files
Conventionally, two types of weather data are used in building design. The first
is a Test Reference Year (TRY); this consists of hourly values of key weather
variables (e.g. dry-bulb temperature, solar irradiance and relative humidity)
which best represent average observed conditions over a year. This set is used
for assessing annual energy use.
The second is a Design Summer Year (DSY), which presents hourly data for the
same variables that are representative of more extreme summer conditions.
These data are used when modelling performance of the building during periods
of hot weather to assess the likelihood of over-heating.
The output from the UKCP09 Weather Generator was used as the basis for
developing modified TRY and DSY ‘weather files’ for three locations: London,
Manchester and Edinburgh. This was done for seven future time periods between
2020 and 2080 and for three emissions scenarios. In total, 21 TRY and DSY were
developed for the 3 locations.
The output from the UKCP09 Weather Generator does not include some
important variables that TRY and DSY rely on. The COPSE research developed
methodologies to derive wind speed, wind direction, cloud cover and barometric
pressure in order to fill these gaps.
2. Modelling future heating and cooling requirements
The TRY and DSY representing possible future climates were used to model the
future heating and cooling requirements for four contrasting existing buildings –
an office building, a primary school, a hospital and a residential care home for
the elderly (see Figure 1).
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Figure 1 “Thumbnails” of case study buildings
Each of the buildings was simulated using ‘EnergyPlus 6’ software for time
periods centred on 2030, 2050 and 2080 across three locations: London,
Manchester and Edinburgh (i.e. the same building was modelled with weather
data relevant for each of these locations).
3. Testing thermal comfort standards
The development of the climate scenario modelling methodology allowed
researchers to test different thermal comfort standards and the implications
these could have for energy use for cooling across a range of possible future
climates.
As part of this process they developed the concept of “Adaptive Comfort Degree
Days” (ACDD) – a metric of how much energy is required to cool buildings under
future climate change scenarios which takes into consideration the inhabitants’
ability to adapt to high temperatures or cool themselves without necessarily
resorting to air conditioning.
In this instance, the research showed that ACDD was a good metric for annual
cooling energy consumption, and that by extension was a good metric for the
potential energy savings to be made by relying on passive cooling measures and
natural ventilation instead of introducing air conditioning.
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3. Assessing national demands
Research undertaken within COPSE also aimed to quantify the implications of
future energy requirements for heating and cooling for the entire national stock
of buildings. The basis of this was a series of graphs, which describe the
relationship between “Space heating gas consumption” and outside temperature
for different regions of the UK (see Figure 2).
Daily mean temperatures for future time periods, under different emission
scenarios, and for a location typical of each of the region, were calculated from
multiple runs of the UKCP09 weather generator. This was used to calculate the
national heating energy consumption for the country.
Figure 2 Relationship between Space Heating Gas Consumption for the North West UK
and the Effective Temperature measured at Woodford for the period 2007–2010.
Results and interpretation
The COPSE project had a broad scope to examine the potential impact of climate
change on the design and operation of buildings over the coming decades. The
core element in the project was the development of a methodology to ‘translate’
output from the UKCP09 weather generator for use in software commonly used
in building design and operation.
As part of the research there were a number of applied examples where this
data was used to assess future energy demands of individual buildings, for
example across the four shown in Figure 1. The projected annual energy
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requirements for the three example locations are summarised in Figure 3. It
shows a trend towards increased demand for cooling. A similar analysis was
carried out for future heating requirements, where demand in winter is projected
to decrease
Figure 3 Annual cooling energy requirements – a) Office b) School c) Hospital d) Care
home
The development of the climate scenario modelling methodology allowed COPSE
researchers to test thermal comfort standards and the implications these could
have for energy use for cooling across a range of possible future climates.
Figure 4 shows that one particular standard, European Adaptive Standard (EAS),
results in more Adaptive Comfort Degree Days (ACDD) than another, ASHRAE
Adaptive Standard (AAS). The graphs indicate that EAS resulted in significantly
more ACDDs over the future projections and the conclusion was that the
potential energy saving achieved by an EAS-compliant building would be higher.
These findings reflect the higher upper limit of the thermal comfort zone in the
EAS, which enables a greater number of buildings to use natural ventilation.
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Figure 4 Annual number of cooling ACDDs for the AAS and the EAS for (left) High and
(right) Low emissions scenarios for Edinburgh, Manchester and London for the 2020s,
2050s and 2080s.
Finally, output from the UKCP09 Weather Generator was used to assess potential
changes in heating energy requirements across the UK. The study showed that,
depending on the emissions scenario chosen, space heating energy demand in
the present UK building stock may fall by 16-18% in the 2030s with a further
steady decline over the next 50 years, so that demand in the 2080s level was
27-43% lower than at present (see Figure 5).
Figure 5 Annual Space Heating Gas Consumption under Low, Medium and High Emissions
scenarios.
Difficulties & limitations
COPSE has gone a long way to bridge the apparent gap between the outputs
provided by UKCP09 and the needs of professionals interested in buildings and
energy. However there remains the difficult task of taking account of potential
changes in weather patterns, when these can only be projected on a probabilistic
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basis. The assessment of risk – e.g. the risk of overheating – given a relatively
large envelope of uncertainty can be complex.
A further difficulty that remains following the work of COPSE is that their
estimates of future energy requirements assume no change in the building
stock. But there will of course be changes in future decades, of which the most
significant for heating energy use will be the introduction of energy efficiency
measures in the present stock, the replacement of some of the present stock by
new, more thermally efficient buildings, and the overall increase in stock
expected over the next decades in response to population pressures.
Estimating the impact of these changes was outside the scope of the research,
but the future weather files derived through COPSE may be used in combination
with consumption data revised to reflect stock changes to provide more realistic
estimates of future heating energy consumption.
Lessons learnt

Irrespective of changes in the building stock, climate change is likely to
have a significant impact on space heating and cooling energy use. With
buildings accounting for a significant proportion of UK carbon emissions,
and playing a key role in the health and welfare of the population, it is
essential that they should be both efficient and comfortable, now and in
the future.

COPSE research has added to our understanding of the issues, and
improved our ability to design and adapt buildings so that they will
function effectively in future climates.
Find out more
A complete list of COPSE publications is included in the full project summary
report
Download the full project summary report [21 MB]
Levermore, G.J., Courtney, R., Watkins, R., Cheung, H., Parkinson, J.B.,
Laycock, P., Natarajan, S., Nikolopoulou, M., McGilligan, C., Muneer, T., Tham,
Y., Underwood, C.P., Edge, J.S., Du, H., Sharples, S., Kang, J., Barclay, M. And
Sanderson, M. 2012. Deriving and using future weather data for building design
from UK climate change projections – an overview of the COPSE Project.
Manchester University, UK.
Publication date [01/09/2014]
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