Taking a basic office design and making recommendations to reduce energy consumption, lower the carbon footprint and provide passive means of ventilating and cooling the building together with improving natural light while reducing solar gains

1. 1.0 Energy in Buildings - Assignment B: Office Building Proposals
By Robert Atherton - January 2008
2.0 EXECUTIVE SUMMARY
Through the use of pre-cast concrete follow core floor modules to heat and cool incoming air to condition Page | 1
the internal spaces, this provides a passive means of controlling the internal environment with minimal use
of plant requirements. This coupled with more effective use of lighting and equipment will see significant
reductions in cooling during the summer periods.
The result is a low energy building with excellent potential for significant reductions in energy use and
carbon emissions, while providing a comfortable, controllable working environment.
It is envisaged that using the ECON 19 documents as a reference, using the above mentioned strategies,
the carbon emissions of the proposed building can be reduced by up to 50%, with a 24% improvement
on the insulation value of the building.
3.0 INTRODUCTION
The report will assess Proposal A for a three storey open plan office, to be constructed in an out of town
location in the south-east of England. It will highlight issues with the proposed construction and operation
and how it relates to energy usage and carbon emissions.
The report will then propose alternative solutions to providing an equivalent building that will have reduced
energy costs and carbon emissions than the original proposal that will fit within the allocated budget.
The current Proposal A has high energy demands due to the cooling, lighting and ventilation requirements
of this deep plan office. These are the 3 main criteria that need to be addressed, looking at the building
design as the principle element for improvement supported by low energy ventilation and heating and
cooling systems, providing a comfortable, controllable internal environment
4.0 ASSESSMENT OF PROPOSAL A
BUILDING DESIGN
Proposal A has lightweight insulated construction to the walls and the roof, together with concrete floor
slabs, all supported by a steel frame. The external building fabric is adequately insulated by modern
standards, but will not absorb heat and will therefore allow the internal environment to fluctuate in
temperature in line with the external temperature which puts extra load on the heating and cooling
systems to deal with the temperature swings. The roof insulation is situated at the pitch of the roof, thus
increasing the volume of building to be heated, cooled and ventilated.
The building has a Heat Loss Parameter of 2.30 W/m2K (Calculation 2 of Appendix A )is a measure of
the whole buildings air tightness and insulation measure on a square metre basis and a Fabric Heat Loss
of 67.2 mW (calculation 3 of appendix A). We will use this figure to compare with the revised building
proposal.
COOLING
The proposed Variable Air Volume air conditioning system is suited to a multiple use occupancy buildings
where the ventilation and cooling requirements vary for different parts of the building, rather than a single
occupancy building such as this. There are also issues with balancing the ventilation requirements as the
air is provided at the same temperature by the Air Handling Unit (AHU) to all areas. The temperature is
then regulated by the amount of the cooled air is supplied to the space. This can cause discomfort and
even inadequate air supply.
The cooling is required to counter act the effects of internal heat gains from lighting, equipment and
occupants as well as background heating and will be required for large periods of the year.

2. Cooling has high energy demand, particularly with fans, pumps and controls and we should there look to
avoid the use of these and look at alternative means of cooling and ventilation.
VENTILATION
Ventilation is provided via the VAV air conditioning system for supply air which pressurises the room and
extracts the warm stale air back into the system, some of which will be filter and re-circulated if required.
Page | 2
Based on the number of potential occupants, we require 0.8 air changers per hour to provide fresh air.
Refer to calculation 4 of Appendix A.
It is important to have regulated supply of fresh air to deal with CO2 and other contaminants that can
cause tiredness and other more serious ailments that lead to slow productivity and even sickness.
LIGHTING
The natural daylight is provided via perimeter windows to the wall, evenly spread around each of the walls.
There is also a central atrium that provides natural daylight to the deep plan office. The ceiling height is
restricted by the suspended ceiling which restricts the light penetration into the office space illustrated in
figure 1 below.
Windows are evenly distributed, regardless of orientation, and no solar shading is proposed which will
lead to excessive glare and solar gain from the east, south and west elevations.
Artificial light is provided via recessed light fittings in the office (400 lux) and to the other service areas
(250 lux). With some internal areas not receiving adequate daylight penetration (figure 1), there will be a
requirement for full time artificial lighting.
Figure 1
HEATING
The heating is currently provided via a condensing gas fire boiler which heats perimeter radiators. This
will be used to heat already cooled air provided by the VAV system which is using dual energy demands
to provide ventilated temperate supply air.

3. OCCUPANTS & EQUIPMENT
With the number of potential occupants in the office, we have estimated the number of general office
equipment to calculate energy use & heat gains. The overall heat gains, including the lighting equate to
46.5 W/m2 with the server room equating to 108.5 W/m2.
These figures represent high levels of heat gains within the office. This would help with heating in the
Page | 3
winter period, but in the summer periods, cooling requirements will increase resulting in high energy
energy use. Refer to Appendix B for calculations of occupancy & internal heat gains
SUMMARY
With high levels of cooling, lighting, internal heat gains, solar gains and large building volume, this
increases the load on cooling, heating and ventilation plant resulting in high energy use and increased
carbon emissions, mainly powered by electricity which has the worst rate of carbon emissions.
According to ECON 19 (1), a typical building of this type, Office Type 3, Good Practice is 85kgCO2/m2
for treated floor area. We will look to reduce this figure with the alternative proposals.
4.1 PROPOSED RECOMMENDATIONS – PROPOSAL B
We will look at Proposal A and highlight which areas can be improved to provide a more energy efficient
low carbon building. We will look at the proposals in the 4 main criteria as follows:
1. Facade & Building Design
2. Maximising daylight
3. Building ventilation, cooling & heating options
4. Internal equipment and lighting
FAÇADE AND BUILDING DESIGN OVERVIEW
Reconfigure the building design to provide more natural daylight and solar shading. This will also allow for
passive solar gain in the winter to reduce the load on the heating system.
The building structure (including the beams and columns) will be changed to dense concrete to provide
exposed internal high thermal mass which will help to dampen and moderate the effects of high external
temperatures together with high internal heat gains, working in conjunction with ventilation systems.
However, acoustics need to be considered.
The building fabric insulation will be upgraded (Refer to appendix E) to improve thermal resistance to
retain heat inside the building in the winter months and reduce the load on the heating system.
A summary of the proposed thermal performance represented as U values (the lower the value, the better
performance), Heat Loss Parameters and Fabric Heat Loss for Proposal’s A and B are summarised
below in Tables 1 and 2 for comparison:
Table 1 – U value comparison - Refer to Appendix C for U value calculations for proposal B
U value in W/m2K
Element Proposal A Proposal B Improvement
Walls 0.35 0.20 43%
Ground Floor 0.15 0.15 0%
Roof 0.25 0.12 52%
Windows 1.80 1.60 11%
TOTAL AREA U VALUE (U.A) 1271.30 967.34 24%

4. Table 2 – Heat Loss Parameter & Fabric Heat Loss Comparison
Item Proposal A Proposal B Percentage improvement
Heat loss Parameter 2.30 W/m2 1.82 W/m2 21%
Fabric Heat Loss 67213 kW 60830kW 9%
Page | 4
Refer to Appendix A and D for calculations of the above
High thermal mass can provide cooling of up to 25W/m2 and so by exposing the high density concrete
structure, we can utilise the building fabric to absorb the heat of the day and release it at night using night
time cooling. Refer to Appendix F for more details on high thermal mass.
The building plans have been modified to maximise the day lighting and solar shading required to provide
a comfortable, well lit internal environment. Please refer to the plans in Appendix G
LIGHTING & SOLAR SHADING
Maximising natural daylight means less use of artificial light reducing energy costs and internal heat gains.
We therefore propose alterations to the building form to allow daylight to cover the whole floor area.
We recommend the following for all of the proposals:
• Increase the second floor area to maximise the space with the most light. The ground floor is
reduced in width to allow better daylight coverage to this area.
• Southern elevation steps out as the building rises to provide solar shading to floors below in the
summer months and allow for passive solar gains from the low winter sun in the winter.
• Widen the atrium as it goes down a floor to maximise the angle of daylight
• Remove the false ceiling to give more height
• Have high level windows to allow for daylight to project further into the room with reduced glare.
• Intermediate vertical windows to allow for views and additional daylight
• Controllable Brie Soleil solar shading to the east and west elevations to help protect occupants
from the morning and afternoon sun.
Please see Figure 3 for natural day lighting proposals indicated in the environmental strategy section.
From the floor plans (Appendix G), you will notice that the floor plan area increases as it goes up a storey
as discussed.
Figure 2a below indicates a typical overhang used to
provide effective solar shading.
Figure 2b show mechanical extract ductwork fixed to the
underside of exposed concrete soffit. The services are laid
in exposed trays.
Figure 2
As a high profile example of cantilever
floors for shading is the GLA Building,
London, designed by Norman Foster, to Figure 2a Figure 2b
provide natural shading to the south,
south-east and south-west elevations.
(10)

5. Page | 5
Figure 3
The lighting we recommend is for low energy tri-phosphor coated fluorescent lighting with reflective strip
up-lighters that reflect the light onto the ceiling. Lighting to have daylight-linked automatic controls on area
zones to minimise use of electrical lighting.
VENTILATION, HEATING & COOLING OPTIONS
The following proposals have been reviewed due to the location of the site in South-East England, which
is one of the warmest areas of the country. The building is on an open site, with no reported noise or
pollution issues, so external opening windows and louvres would not currently pose a problem. The office
is a single use building and will be controlled via a Building Management System linked to CO2,
temperature and light sensors that will control the internal environment of the building with localised
control given to the occupants.
LOW ENERGY COOLING METHODS CONSIDERED BUT DISCOUNTED:
1. Passive Down-draught Evaporative Cooling – Spraying of tiny water particles at the atrium
passively cooling the air temperature. As the air cools, it sinks creating positive pressure and
pushes the warm air out through the perimeter windows. This is a low energy form of cooling, but
better suited to dryer climates due to the increased internal humidity levels.
2. Displacement Ventilation – Air is brought in at low level, with an air temperature just below the
required room temperature. Buoyancy forces the air to flow across the floor and as it hits people
or other objects, the air warms & rises towards the ceiling. As the air is moves slowly, the warm air
stays at the top of the room, allowing it to be effectively ventilated at high level. The advantage of
this system is that air can be supplied at a higher temperature than conventional cooling systems,
reducing the cooling load on equipment, therefore reducing energy use. While effective, it is not
the best cooling system to use with natural ventilation and still requires mechanical plant for much
of the year.
3. Chilled Beams – These are ceiling mounted ‘beams’ that contain finned elements that have
flowing cooled water passing through them via pipework to produce cool air that, through
buoyancy flows down towards the space below to push the warm air out of the space. Draughts
can be caused, but the advantage of this system is water has a higher thermal density than air
and is therefore more efficient. This would be a good combination with a heat recovery
mechanical ventilation system, but has difficulty with close temperature control.

6. CHOSEN VENTILATION AND COOLING PROPOSALS
HOLLOW CORE SLAB COOLING – PROPOSAL B1
This method of cooling uses pre-cast concrete slabs (exposed thermal mass) with hollow cores. The slabs
are connected to join up the hollow cores to form air paths. Supply air is passed through the hollow core
air paths which upon contact, exchanges temperature with the slab. Page | 6
If windows are used for natural ventilation, then the supply sir though the window is mixed with and
therefore cooled by the air supplied through the hollow core slab.
So at night, cool air is passed through the slab to lower the temperature. The following day as the warmer
supply air is pre-cooled by the slab. So this allows the floor slab to absorb internal heat gains from the
occupied space AND cool the incoming supply air.
In the winter, during the night, the system is shut to allow the stored heat within the thermal mass to be
steadily released into the occupied space below to reduce heating requirement in the morning.
The following day, the heat that remains in the hollow core slabs warms the cooler supply air before it
mixes with the internal air.
The air is supplied to the slabs via an Air Handling Unit which then filters and controls the flow of air
through the hollow core slabs. This system is recommended for dealing with internal heat gains below
50W/m2 (11). Our internal heat gains equal 46.5W/m2, so the system would be advantageous.
This method of cooling has been used on a building in Leeds called the ‘Innovate Office’ (12). The system
was chosen to take advantage of the excellent thermal storage and to significantly reduce the cooling
load. The other plus, was the offices could be marketed as conditioned, as in the internal environment
such as air supply and temperature is controlled. See advantages and disadvantages in table 3
Table 3
Advantages Disadvantages
• Low running and maintenance costs • High capital installation costs
• Low energy cooling system • Requires some plant space for AHU
• Up to 90% heat recovery from extracted air • Cannot deliver close temperature control
• Quiet operation • Cooling suitable for internal heat gains of
• Filtered clean regulated air supply <50W/m2
• Heating may be an issue so would
• Minimises draughts
• Conditioned internal space recommend back up heating in winter.
MIXED MODE VENTILATION STRATEGY – PROPOSAL B2
Mixed mode ventilation is a combination of natural ventilation and mechanical ventilation with heat
recovery. The system is designed to maximise natural ventilation and passive cooling in the summer while
utilising the mechanical ventilation system in the winter months with the heat recovery method to provide
clean warm air at controlled minimum air changes. This avoids the draughts and effectively controls the
internal temperature and air quality. Refer to figure 3 for natural ventilation function diagram.
According to GIR 85, New ways of cooling (11), this type of ventilation and cooling method is suitable for
heat gains less than 30W/m2 (11). We have heat gains of 46.5W/m2 and are therefore significantly higher.
However, natural ventilation systems have been successfully used in buildings such as the Queens
Building, DMU(9), where internal gains were as much as 117 W/m2. With careful design and analysis, the
building can be designed to cope with these heat gains.
This system, linked to a BMS works using external openings that supply the building with air which is
warmed by internal heat gains and solar passive gains and becomes lighter and more buoyant which
allows the warmed air rise and ventilate through the atrium at the top through of the centre of the building,
pulling cooler air in through the perimeter windows and low level louvres.

7. At night time operation, the high thermal mass has absorbed the heat from the day and will release this at
night assisted by closing the main vents to the atrium, but opening the perimeter high level windows to
allow the air to flow across the underside of the exposed mass and cool it carrying the heat out of the
building. By the morning, the concrete will be cooled down and will radiate coolth, reducing the cooling
load.
The warmer the supply air and the internal heat gains, the more air changes are required. We have plotted
Page | 7
the required air flow chart based upon average maximum temperatures in this location. Please see the
chart represented in Figure 4 below. While the air changes increase above 15 air changes per hour in July
and August, the chart does not take into account the thermal cooling of high thermal mass which can
account for up to 25 W/m2 which will reduce the load of the natural ventilation air changes required to cool
the building.
Figure 4 – Figures for temperature provided by BBC website (7)
During the winter, Windows are generally closed in the winter to prevent heated air being wasted.
The heat recovery ventilation system extracts to warm polluted air which passes over a heat recovery
system that warms the incoming supply air, reducing the load on the heating system. The system also
provides the option of re-circulating some of the extracted air, by filtering and mixing this with the incoming
air, to warm the air even more. Air is supplied and extracted via ductwork fixed to the underside of the
exposed concrete floors Air changes and temperature can be effectively controlled using this method. See
advantages and disadvantages in table 4. See figure 2b for picture of typical ductwork.
Table 4
Advantages Disadvantages
• Control of air supply, particularly in winter • Plant space required and ductwork to ceilings
• Greater control of air temperature in winter • Mechanical plant running during periods of the
• Can utilize natural ventilation option for year resulting in higher energy costs and carbon
emissions than natural option.
majority of the year so low energy.
• Maintenance of ventilation system
• Can support natural ventilation in the
• Relies on buoyancy driven air movement
summer with supply air to help promote air
• Wind protection may be required so not to
flow.
• Provides up to 80% heat recovery deflect flow of air
• Secure night time cooling • Security at night if windows are left open for
• Lower energy use and carbon emissions night time cooling
• Ideally suitable for internal heat gains <30W/m2
• Control of temperatures in summer an issue

8. OCCUPANTS AND EQUIPMENT
The following recommendations are to be made
1. Exchange the PC’s for laptops, to reduce energy and intrenal heat gains.
2. Position the photocopiers in the space adjacent to the stack serving the server room to provide
additional ventilation and cooling to this area reducing the overall heat gains.
3. Provide ventilation stack to the server room and service area (photocopiers and other high internal Page | 8
heat gain equipment) to assist in ventilating and cooling to north elevation.
The server room will require comfort cooling, but with a dedicated stack and fresh air inlet, coupled with
the proposed cooling system will reduce the load.
5.0 CONCLUSIONS AND RECOMMENDATIONS
If we take the original ECON 19 (1) rating for an air conditioned Office Type 3, good practice, the CO2
emissions were 85kgCO2/m2 of Treated Floor Area (TFA). In using the just a natural ventilation method,
we adapt the ECON 19 Office Type 2, good practice, we expect to reduce the carbon emissions by up to
50% based on the figures illustrated as 43 kgCO2/m2 of TFA. However, the proposed methods put
forward in the report incorporate some additional mechanical input and so the energy savings would be
slightly lower than the figures quoted above.
Insulation levels have been increased and resulted in an overall improvement of 24% on the insulation
level and 21% on the Heat Loss Parameter. Significant improvements that will lead to reduced heating
requirements and reduced energy costs and carbon emissions.
To provide a conditioned internal environment to control air quality, temperature and passive cooling, we
recommend Proposal B (Building Modifications) combined with proposal B1 (Hollow Core Slab) to provide
a proven cooling and ventilation system that is known to achieve the required cooling to overcome the
internal heat gains using low energy methods
Both the systems used in conjunction with the proposed building fabric alterations offer a low energy office
solution with significant improvements over Proposal A as summarized below in Table 4:
Table 5
Proposal A Improvements with Proposal B1
Building Adequate, but basic levels of insulation Improved insulation has reduced fabric heat
Insulation loss
Building Lightweight elements lead to internal High thermal mass dampens high
Structure temperature fluctuations relying more temperatures and works in conjunction with
on services to control internal low energy ventilation and cooling
environment strategies
Daylight Even distribution, but no solar shading High ceiling heights, wider atria, high level
or protection from solar gains, low windows and solar shading maximizing
ceiling heights prevent light distribution daylight reducing energy usage for lighting
Ventilation Via VAV system, high energy use and Low energy natural ventilation provides air
difficult to control temperatures and air flow to satisfy air quality requirements
flow
Cooling VAV system with pumps, fans and Hollow core floor ventilation system
plant, high energy, but effective at exchanges heat with high thermal mass
cooling concrete and regulates internal temperature
Heating Central heating system with no heat Hollow core floor system adjusted during
recovery so in efficient winter to provide passive heating using high
thermal mass storage.
Lighting Standard light fittings, no indication of Highly efficient light fittings on zoned control
zoning linked to BMS
Occupants and High internal heat gains evenly Zone to position high internal heat gain
Equipment distributed cause equipment and server room with cooling
assisted by ventilation stack

9. ADDITIONAL NOTES
We would also recommend photovoltaic panels to provide supplementary electricity, greywater recycling
to provide water for toilet cisterns, external watering etc and to supply an external water feature to the
south elevation to cool air before it enters the building.
Page | 9
6.0 REFERENCES
1. ECON 19 (2003) Energy Consumption Guide 19, Energy use in offices
2. IRVING, S. FORD, B. ETHERIDGE, D. (2007) AM:10 2005 Natural ventilation in non-domestic
buildings, CIBSE
3. MCMULLAN, R. (2007), Environmental Science in Buildings, Sixth Edition, published by Palgrave
MacMillan
4. Good Practice Guide 257 (1998), Energy efficient mechanical ventilation systems, provided by the
Carbon Trust
5. Environmental design (2006), CIBSE Guide A, 7th Edition, CIBSE
6. General Information Report (1999) Mixed-mode buildings and systems – an overview, BRE and
CIBSE, obtained from the Carbon Trust
7. Weather Data (2007) BBC Weather data, http://bbc.co.uk/print/weather/world/city_guides
8. NEVILL, G. (2007) So, How are you doing?, Heelis, National Trust HQ review, BSJ 11/07, CIBSE
9. THOMAS, R. (1999) Environmental Design, Second Edition, published by Spon Press.
10. http://www.nyclondon.com/blog/archives/2004/09/22/london_city_hall_gla_building_by_norman_foster
.blog
11. General Information Report 85 (2001) New ways of cooling
12. PEARSON, A. (Sep 2007), Article: BREEAM DREAM in BSJ, published by CIBSE
WORD COUNT: 3962 (excludes text on drawings)

10. 7.0 APPENDICES
APPENDIX A – PROPOSAL A
U VALUE (W/m2 AREA x U VALUE
EXISTING AREA m2 K) (A.U.)
Page | 10
EXTERNAL WALL 907.4 0.35 317.58
WINDOWS 370.1 1.80 666.23
GROUND FLOOR 750.0 0.15 112.50
ROOF 700.0 0.25 175.00
1271.31
TOTAL (W/m2 K)
Inside Temperature = 20 degrees McMullan
Outside Temperature = -1 degrees
21
Temperature Difference = degrees
VOLUME OF OPEN PLAN OFFICE SPACE WITH
ATRIUMS = 9137 m2
CALCULATION 2 - HEAT LOSS COEFFICIENT & PARAMETER
Heat Loss Coefficient = (sum 1/3 x N (ach) x V (Volume)) + (Sum U (U Value) x A (element area))
Units
Air Changes per hour(N) 0.640
Volume (V) m3 9137.00
U Value x Area (W/m2 K) 1271.31
3220.11
So HLC = (sum 1/3 x 0.79 x 7431.5)+(1181.31) = W/K
2.30
Heat Loss Parameter = HLC / Floor area = W/m2k
CALCULATION 3 - FABRIC HEAT LOSS
FABRIC HEAT LOSS calculated =(Sum U (U Value) x A (element area)) x (Ti - To (temp difference))
Therefore FHL = 26697.431 kW
kW
Vent Heat Loss = 1/3 ach x Volume x Temp Diff 40515.552
67212.983
Total Heat Loss = kW
CALCULATION 4 - AIR CHANGE CALCULATION BASED ON 8 LITRES PER PERSON PER
SECOND
Allowance of 8 litres per second per person
0.008 x 3600(seconds) = 28.8 m3/h
Total required for 203 occupants = 5846.4 m3/h
Airchanges = m3/h / volume
airchanges per
Therefore 5846.4 m3/h / 9137m3 0.64 hour
Total external fabric exc. ground floor 1977.5
Air Infiltration 2m3/h per m2 So air
infiltration is 1977.5m2 x 2m3/h = 3955.0 m3/h
(3955m3/h / 3600) x 1000 = 1098.6 L/s
Infiltration rate of 50PA, factor of 20
So 1099/20 = 54.9 L/s
Infiltration rate = l/s x 3600/1000 =
m3/h 192.6 m3/h
Airchange rate = m3/h / volume = ac/h 0.021 ac/h
airchanges per
0.619 hour
Therefore airchange - air infiltration =

11. APPENDIX B - OCCUPANCY & INTERNAL HEAT GAINS
MAIN OFFICE
Total Heat
Heat Gain Heat
gain (kW)
Item Number per item (W) gain/m2 (W)
Area (usable floor area m2) 2025
9.0
Occupants (1 per 10m2)1 203 90 18.2 Page | 11
2.0
Photocopier (1 per 40 people) 5 800 4.1
15.0
Computer (1 per person) 203 150 30.4
0.5
Printer (1 per 20 people) 10 100 1.0
20.0
Lighting (400 lux per m2) 2025 20 40.5
SERVER ROOM
Server Room Machines 20 120 2.4
Lighting (250 lux per m2) 25 13 0.3
SERVICE AREAS
12.5
3.4
Lighting (250 lux per m2) 275 13
(1)Heat gains for occupants excludes latent heat gain which turns to moisture
APPENDIX C - ALTERNATIVE BUILDING FABRIC U VALUES
TABLE C1
Thickness Thermal
Element metres (d) Conductivity (k) Resistance (r) Calculation
Wall Build up -
Proposed W/mK (m2 K/W)
Internal Surface - - 0.120
Dense Blockwork
(Forticrete Facing) 0.140 1.460 0.096 Resistance - r = d / k
Celotex Partial fill
insulation 0.100 0.023 4.310
Cavity 0.050 - 0.180
Brick Outer 0.105 0.840 0.125
External Surface - - 0.080
TOTAL
RESISTANCE 4.911
U Value - U = 1 / Rt
0.204
= W/m2 K
TABLE C2
Thickness Thermal
Element metres (d) Conductivity (k) Resistance (r) Calculation
Roof Build up W/mK (m2 K/W)
Internal Surface - - 0.220
Concrete slab 0.250 2.300 0.109
Concrete
sand/cement screed 0.075 0.410 0.183
Kingspan insulation 0.200 0.026 7.605 McMullan p,23
Single ply membrane 0.012 0.230 0.052
External Surface - - 0.050
TOTAL
RESISTANCE 8.218
U Value - U = 1 / Rt
0.122
= W/m2 K

12. TABLE C3 Exposed
floor U value
Thickness Thermal
Element metres (d) Conductivity (k) Resistance (r) Calculation
Exposed Floor build
Up W/mK (m2 K/W)
Internal Surface - - 0.150 Page | 12
Concrete slab 0.250 2.300 0.109
Kingspan insulation 0.200 0.026 7.605
Hardwood Boarding 0.020 0.180 0.111
External Surface - - 0.050
TOTAL
RESISTANCE 8.024
U Value - U = 1 / Rt
0.125
= W/m2 K
APPENDIX D - ALTERNATIVE DESIGN HEAT LOSS CALCULATIONS
U VALUE AREA x U
EXISTING AREA m2 (W/m2 K) VALUE (A.U.)
EXTERNAL WALL 901.7 0.20 183.95
WINDOWS (Velfac 200 System) 352.8 1.62 571.54
GROUND FLOOR 625.0 0.15 93.75
EXPOSED UPPER FLOORS 165.0 0.13 20.63
ROOF 799.0 0.12 97.48
TOTAL (W/m2
967.34
K)
Inside Temperature = 20 degrees
Outside Temperature = -1 degrees
21
Temperature Difference = degrees
VOLUME OF OPEN PLAN OFFICE SPACE WITH ATRIUMS = 8055.000
CALCULATION 2 - HEAT LOSS COEFFICIENT & PARAMATER
Heat Loss Coefficient = (sum 1/3 x N (ach) x V (Volume)) + (Sum U (U Value) x A (element area))
Units
Air Changes per hour(N) 0.726
Volume (V) m3 8055.00
U Value x Area (W/m2 K) 967.34
2916.14
So HLC = (sum 1/3 x 0.79 x 7431.5)+(1181.31) = W/K
1.82
Heat Loss Parameter = HLC / Floor area = W/M2k
CALCULATION 3 - FABRIC HEAT LOSS
FABRIC HEAT LOSS calculated =(Sum U (U Value) x A (element area)) x (Ti - To (temp difference))
Therefore FHL = 20314.052 kW
Vent Heat Loss (1/3 ach x Volume x Temp Diff)= 40515.552 kW
60829.604
Total Heat Loss = kW
CALCULATION 4 - AIR CHANGE CALCULATION BASED ON 8 LITRES PER PERSON PER
SECOND
Allowance of 8 litres per second per person
1 m3 = 1000 litres
Therefore 8 litres = 0.008 m3
0.008 x 3600(seconds) = 28.8 m3/h
Total required for 203 occupants = 5846.4 m3/h
Airchanges = m3/h / volume
Therefore 5846.4 m3/h / 8055m3 0.73 ACH

13. Air Infiltration 2m3/h per m2
Total external fabric exc. ground floor 2218.5
Air Infiltration 2m3/h per m2So air infiltration is
2218.5m2 x 2m3/h = 4437.0 m3/h
(4437m3/h / 3600) x 1000 = 1232.5 L/s
Infiltration rate of 50PA, factor of 20
Page | 13
So 1233/20 = 61.6 L/s
Infiltration rate = l/s x 3600/1000 = m3/h 192.6 m3/h
Airchange rate = m3/h / volume = ac/h 0.024 ac/h
0.702 ACH
Therefore Requires airchange - air infiltration =
APPENDIX E FOR FABRIC SPECIFICATION
We have assumed a ceiling will be installed on the second floor to contain service ducts and associated
services.
WALLS - 140mm dense painted blockwork innerleaf (high thermal mass), 100mm Kingspan Insulation,
50mm clear cavity, 102mm facing brickwork outerleaf (absorbs external solar gain)
ROOF - 250mm reinforced concrete slab with exposed soffit (high thermal mass), 75mm sand/cement
screed, 200mm Kingspan insulation, Waterproof Membrane, Sedum roof (optional)
EXPOSED UPPER FLOORS - 250mm reinforced concrete slab with exposed soffit (high thermal mass),
200mm Kingspan insulation to u/s of slab, 20mm hardwood boarding on battens
UPPER FLOORS - 250mm reinforced concrete slab with exposed soffit (high thermal mass)
VELFAC COMBINATION WINDOWS - Durable softwood inner frame, Powder coated aluminium outer
frame, Double glazed argon filled sealed window unit, Low E internal glass to reflect heat into the building,
Solar glazing external to help reflect solar gain out of the building preventing overheating
APPENDIX F FOR HIGH THERMAL MASS
• Provide passive cooling of up to 25W/m2.
• Provides ‘thermal lag’ so the internal temperature is not immediately affected by the external
temperature reducing the load on the heating/cooling systems.
• Provides more constant temperature control. Absorbs internal heat and passive solar gains during
the day reducing load on cooling requirements.
• Releases heat at night using night time cooling, acts like a storage heater.
• Radiates ‘coolth’ in the morning, reducing load on cooling system and starts again to absorb the
day’s internal heat gains.
• In the winter, it can also absorb heat from the heating system and release at night, but without
opening windows, this allows the heat to be retained in the building to reduce the heating load in
the morning.

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Please note the bridge that crosses the atrium is at different angle to the floor above to limit shadowing
below.
APPENDIX G – FLOOR PLANS