DEN5208 – Coursework – Project: Insulating a house on a budget Paper report

DEN5208 – Coursework – Project: Insulating a house on a budget
Paper report Due Friday, 16 March 2018. (Start early, you won’t do well if you give it only 1 week).
You are a sustainability engineer who was very successful at consulting and now work on a
makeover show. Instead of people you makeover houses for energy efficiency. You know all the
different ways in which heat is lost – conduction, convection, radiation.
On the current show you have a budget of just £2500 to makeover the following house:
3-bedroom terraced house (two outside walls, two walls with neighbours), with ground, first floor,
and a loft (only for storage). Walls are hard (with unfilled cavity of 8 cm) with an effective R-value of
0.7 K/(m2 W), with outside wall dimensions (h x l) 5mx10 m and 10m width of the common walls
with neighbours. Assume that currently the air in the room easily exchanges with the air in the
cavity. But if you insulate it, with a filler, it won’t. Assume also that your neighbours keep the rooms
at the same temperature as you. Roof is slanted at a 45 degree angle, and also has R-value of 0.7
K/(m2 W). The loft is not insulated. From the gas boiler (inside the house) there are 20 m of exposed
hot water heat pipe (15 mm inside diameter, assume 1mm thickness if necessary), carrying 80 o
water to the rest of the house – both for hot water and heating, at a speed of 500 L/h (linear speed
1.48 m/s). There are 5 radiators, average surface area 1 m2 each, all on (the inside of) outside walls.
There are currently no curtains. The rates for gas are 4 p/Kwh equivalent, and for electricity 12
p/Kwh equivalent.
The current lighting includes 20 incandescent lightbulbs (60W ea) which are all used on average for 3
hours in the winter and 2 hours in the summer, so the number of lightbulbs and this level of
illumination should be maintained even if the type of lightbulbs is changed. There are 7 single-glased
windows, all 4mm thick glass (3 windows of 2 m2
, and four 1 m2
). Two of the 1m2 windows are on
the doors (each total door area is 2 m2
), which on the rest of the area have high R-value of 3.5 K/(m2
W), but have gaps, which might need foam insulation to prevent air leaking. Let’s assume that the
goal is to maintain a comfortable 21 o
C inside the house throughout the year. Floor is completely
insulated with a temperature the same as the inside of the house.
Assume two seasons of 6 months, (30days/month) respectively. (Winter, with outside temperature
of 0 o
C at night and 7 o
C in the day, and summer with outside temperature where the day is 20 o
and the night is 13 o
C.) Also, there are 2 people in the house during the day and 5 people at night.
Assume each person is a 100 W heat source.
Tasks, Determine:
a) Initial yearly heat/light consumption (in both J & £), considering conduction, convection, radiation
b) Insulate the house by finding available data for costs and installation of:
– Rock wool, foam pipe insulation, reflective insulation sheets and reflective foam panels.
– Well-insulated doors, LED lights, and heavy (black-out) curtains, etc.
present the most convincing case for the highest energy saving one could do with the available
budget, based on detailed calculations of the modified heat-loss through all 3 mechanisms.
Two Google drive files to share information on materials and service costs, all the class can
– a spreadsheet with materials costs:
– a text document for notes/discussion:
For initial house state analysis 40% – broken into:
Heat loss via walls 6%
Heat loss via attic/roof 6%
Heat Loss via windows 6%
Heat loss via doors 5%
Heat of long uninsulated pipe 8%
Heat loss by radiators near outside walls 6%
Heat from lightbulbs 3%
Redoing the above calculations with new insulation materials 40%–
Considering two dimensions (20% ea)– both energy and cost savings
Heat loss via walls 6%
Heat loss via attic/roof 6%
Heat Loss via windows 6%
Heat loss via doors 5%
Heat of long uninsulated pipe 8%
Heat loss by radiators near outside walls 6%
Heat from lightbulbs 3%
10% Prioritising and providing the best insulation (cost /energy scenarios) with the given budget.
10% for clear, parametrized solutions (in Excel, etc), which let one change solution for
Different Outside temperature, Initial level of wall insulation, total size of windows
Bonus points for:
5% Estimates of heat loss through one or several draughty door/window (not part of current
The group with highest (legitimate, correct calculation) energy saving gets 100%
People should work in teams of approximately 5, as assigned in groups. The group report will be
assessed as a whole, and then each individual will get the group mark multiplied by the average
peer-assessment mark average from the other four individuals in that group.
There are some good tips/resources at:
It is not required, but for everyone’s efficiency it would be good for the class to create a common
database for the best available insulation materials/ installation service costs (double-glased
windows, etc), so less effort duplication will result in more time spent on the optimization problem
from a heat-transfer perspective.
And though the R-value is the total thermal resistance including conduction heat transfer, convective
heat transfer and radiative heat transfer, it is usually rated for normal house temperatures. I.e. for
radiators where the radiative contribution is much higher, it would create a hot spot on the external
wall and much more heat would escape there than from the rest of the wall with the normal room
temperature inside. Here, assume there are no reflective barriers before you do extra insulation. See
the following case studies about a special behind-the-radiator reflective panels:
note the above were sponsored by a company, but the same principles apply and similar benefits
can be obtained also by do-it-yourself setups (possibly even better than some commercials)

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