Environmental Performance Analysis

Climate Characteristics • • • • • •

AT3 Part 2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

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London Climate Moderate with annual average lows of 2 degrees celcius in January and 22 degrees celcius in July Based upon the heating degree days, internal gains and occupancy schedules, it will be possible to establish a series of scenarious for passive and active environmental systems when coupled with solar shading devices, double skin facade design, ground source heat and MVHR This will determine a climate adaptive or rejective scenario for environmental controls within the building envelope taking into consideration the objectives of passive ot mechanical HVAC systems in relatio to occupant comfort levels throughout the year Occupant comfort levels defined for offices at sedentary metabolic rate of in relation to the predicted mean vote index (PMV) according to ASHRAE thermal sensation scale and guidelines. This will vary depending onthe level of control occupants have over their own indoor climate, and the range increases during certain times of year when occupants are more accepting of a wider range of temperature fluctations from the optimum range Main HDD period October to April with brief periods of excessive internal temperatures above comfort level in June and August with possible climate adaptive controls to regulate this

http://www.bbc.co.uk/weather/2643743

A1.2

Climate Characteristics

A1.1

Weather Variables Climate Consultant 5.4 (2012) US Department of Energy Energy Efficiency & Renewable Energy http://apps1.eere.energy.gov/buildings/tools_directory/

Environment and climate conditions

Psychrometry

Occupancy scheduling & lighting

Internal gains and HDD

Comfort indices

Building design methodology

A1

Total Average Heating degree days (HDD) based on Method B, Annex F BS EN 15251:2007 equates to 63 days = 3388 hrs To calculate heating days Method: To find % of occupied hours PMV (Predicted Mean Vote Index) (ASHRAE) thermal sensation scale +3 Hot +2 Warm +1 Slightly Warm 0 Neutral -1 Slightly Cold -2 Cool -3 Cold

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

PMV = (0.303e-0.036M + 0.028)L M = Metabolic Rate L = Thermal Load Calculate difference of latent heat production – heat loss of actual environment M= 1.2 L= -0.85 in Winter L= 0.5 in Summer PMV Winter = 0.837861852 PMV Summer = 0.739289869 HDH (Heating Degree Hours) TBase = 15.5 degrees centigrade Janurary HDHav min temp = 98 HDHav max temp = 20 HDHrec min temp = 211 HDHrec max temp =-111 Comfort Zone 19degrees centigrade- 22 degrees centigrade Working 7am- 5pm (10 hours) HDD (Heating Degree Days) = ∑ (Tbase – Tmean of the day)

AT3 Part 2

PPD = predicted percent of dissatisfied people -0.5 ≤ PMV ≤ 0.5 wf = Θo - Θo,limit 19o C ≤ Θo ≤ 24oC

A2.1

Environment and climate conditions

Working out the time the building is heated; When; 7 months of the year 9 out of 12 hours) 10 hrs per day (out of 24hours) 22 days per month (out of 31 days) 7x9= 63 Weekend 563 not heated =1512 hours Year 5 months not heated = 3720 hrs Night 14x22 days not heated = 308 hours 308+ 3720+ 1512 =5540 8928 hours in a year 8928- 5540= 3388 hours in a year heated (appendix B1.2)

Derived and Calculated Psychometry

Psychrometry and HDD

Occupancy scheduling & lighting

Internal gains

Comfort indices

Building design methodology

A2

Sunpath and Lighting Schedule

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AT3 Part 2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

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Environment and climate conditions

Psychrometry and HDD

A3.2

Schedules

A3.1

Gains Calculations

Occupancy scheduling & lighting

Typical office plan internal gains use divided into categories: lighting, equipment and occupants Each heat source multiplied out by the total floor area and according to use schedules for the floor plan provides an accurate estimation of the total annual gains, taking into consideration 50% standby consumption, 22 hour working months and occupancy volumes By analysing the solar geometry we were able to calculate the times of year when lighting will be on and in which parts of the building. As such, at any one time, schedules show that only certain percentages of the building are likely to be lit simultaneously The internal gains account for a substantial degree of heating within the building envelope. Human occupancy alone accounts for ~24kwh/m2 annually, various schedules of equipment accounting for ~58 kwh/m2 and lighting, primarily energy efficient 18w CFL can fixtures accounting for ~11.6 kwh/m2, accounting to a total sum of ~94 kwh/m2 When calculating a suitable heating and cooling scenario for the building, the internal gains will account for a substantial alteration to the number of heating or cooling days during the year To avoid summertime overheating and to maximise the heating effect of internal gains in the winter, the selection of a passive ot active approach will be fundamental to the overal heating/cooling budget of the building.

Human behaviour is also extremely important when considering ways of minimising inefficiencies in internal gains. By providing the minimum optimal working conditions both in temperature, lighting lux levels, ventillation rates and solar shading, the likelihood of occupants being dissatisfied with internal conditions is increased Occupant interaction should be maximised with building systems to adapt to occupant use, allow manual alterations to climate controls and lighting, and sensed lights should have override functions to prevent excessive operation at unneccessary times.

Internal gains

Comfort indices

Building design methodology

A3

a) Peak

c) Summer Morning

b) Winter Average

d) Summer Midday

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Set up schedules according to extremes of demand fluctuations for summer and winter

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Peak times occur infrequently, but are represented by diagram a) This shows concentrated internal heat gains in rooms including the kitchen, meeting rooms and server room.

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During winter, on average, the heat output from lighting is highest, with a distributed spread of point sources.

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During the summer, heat gains from lighting will vary according to differing times of day as shown. This is related to solar position, occupancy schedules (peak kitchen use, lunch time, meeting room use e.t.c.)

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Equipment such as photocopiers, desktops e.t.c. tend to run constantly during the working day and standby during the night.

Other equipment such as servers, kitchen appliances, phone power supplies e.t.c. run constantly, and lighting, laptop use, chargers e.t.c. are intermittent loads.

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Schedules have been set according to specific equipment to generate as accurately as possible the typical output

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Zones within the building are defined as enclosed spaces, and the heat gains have been plotted accordingly to the ratio of the heat output in watts to the floor area in m2.

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Devices with similar nameplate ratings appear to produce disproportionately scattered heat gains, this is due to the ratio of gains:floor area within individual zones

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Occupants are also included to varying extends according to the time of day, accounting for substantial heat gains within enclosed spaces such as offices and meeting rooms.

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Depending on the HVAC system adopted, damper mechanisms and thermostatic controls should be placed and calibrated according to the distribution of internal gains as well as solar orientation so as not to create cold of warm ‘spots’ which can lead to occupant discomfort

e) Summer Afternoon

AT3 Part 2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

Internal Gains Distribution Mapping

Environment and climate conditions

Psychrometry and HDD

Occupancy scheduling & lighting

A4.2

Distribution Zones

A4.1

Gains Mapping

Internal gains

Comfort indices

Building design methodology

A4

Confort Aims and Environmental Parameters for Occupant Comfort

Jan Feb March April May June July Aug Sept Oct Nov Dec

AT3 Part 2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

Table A.1 — Examples of recommended categories for design of mechanical heated and cooled buildings

Table A.2 — Examples of recommended design values of the indoor temperature for design of buildings and HVAC systems

• Comfort Zone=range of acceptable temperaute and humidity conditions taken for 90% acceptablity from (Tn -0.5) to (Tn +0.5) • Clo=clothing thermal insulation u value = 6.45 w/m2k or resistance 0.155m2k/w over surface area of body • Typical summer clo of 0.35 to 0.6 • Typical winter clo of 0.8-1.0 • Neutrality temperature=median of peoples’ votes index (pmv) Tn=17.8+0.31xT.o.av (mean monthly temperature) • January Tn=17.8+(0.31x6)=19.66 degrees celcius • January Tl=19.16 degrees celcius • January Tu=20.16 degrees celcius • July Tl=24.12 degrees celcius • July Tu=25.12 degrees celcius • 50% RH • Comfort zone shows period of the year during which the dry bulb temperature in relation to relative humidity falls in the region considered most comfortable for occupants (partway May through August) • For periods outside this zone it is likely that the climate will need to be regulated by means of heating, cooling, and dehumidification where necessary • Careful environmental controls coupled with internal gains can minimise dependency on HVAC systems • To maximise comfort levels, mechanical systems can be designed in such a way as to eliminate or substantially limit the effect of draughts and cold spots by blowing a curtain of conditioned/ warm air over the surface of the perimeter windows, negating the natural convective flow that occurs when cold glass surfaces cool the air • Stale air is extracted from the center of the space • Radiant Heat Exchanges through surface materials and thermal mass can create a feeling of warmth of cold regardless of air temperature. The design is likely to be largely composed of low thermal mass partitions, reducing the high thermal mass effect and associated lag times • Air movement and speed optimum range 0.4-1l/s • Average metabolic rate 50% sedentary typing, 25% seated, 25% light walking=1.25 met

A.3 Recommended indoor temperatures for energy calculations Table A.3 — Temperature ranges for hourly calculation of cooling BSEN 152512007 (European Committee for Standardization CEN) (2007)

Environment and climate conditions

Psychrometry and HDD

Occupancy scheduling & lighting

Internal gains

A5.2

Comfort Parameters

A5.1

Occupancy Calculations

Comfort indices

Building design methodology

A5

Climate Analysis and Internal Gains. Report Summary.

Qualitative Comfort Aims • Evenly distributed temperature without cold or hot ‘spots’ which can lead to occupant dissatisfaction • Reduction of drafts • Gentle even light with operable shading to allow maximum user control

AT3 Part 2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

Descriptions of comfort aims (quantitative); • 19-22 degrees • Neutrality temperature +-0.5 • Supplying air at a suitable air speed of 0.4-1.0 l/s at diffusers • 19-22 degrees temperature range • Optimum light level 500 lux Internal gains Maps We produced four internal gains maps; one for winter showing maximum electricity use, one for summer morning, one for summer midday and one for summer afternoon. The diagrams all show use of energy in the kitchen and specifically the midday diagram which also shows energy in the dining areas. Highlighted is the energy emitted from lights and people.

From studying the climate data we were able to see a constant environment must be created within the office that the workers can adapt to. This will create a more comfortable, efficient environment as the workers will not become distracted by being too hot or too cold.

Seasonal temperature variations mean we can adjust our heating system to respond to the outdoor environment to lower heating costs and adapt the temperature to be more suitable to neutrality temperature.

5 Cloud cover, expressed as a fraction of the sky hemisphere; eighths, or more recently tenths) covered by clouds.

6 Sunshine duration, i.e. the period of clear sunshine, measured by a sunshine recorder, in which a lens burns a trace on a paper strip; shown as hours per day or month.

7 Solar radiation Solar control When considering solar control the first thing we did was to determine when solar radiation would be a welcome input or when it should be excluded. We then outlined this overheated period on the sun-path.

The performance of our shading device is depicted by a shading mask.

Shading design External shading devices are the most effective tools to control sun penetration. Two basic categories of shading devices can be distinguished: 1 Vertical devices , e.g. vertical louvres or projecting fins. 2 Horizontal devices , e.g. projecting eaves, a horizontal canopy or awning, or horizontal louvres. These are characterized by a vertical shadow angle . They are most effective when the sun is near-opposite to the window considered.

References: Environmental design CIBSE Guide A (London: Chartered Institution of Building Services Engineers) (1999) Energy efficiency in buildings CIBSE Guide F (London: Chartered Institution of Building Services Engineers) (2004) BSEN 152512007 (European Committee for Standardization CEN) (2007) INTERNAL HEAT GAINS (IHG) Energy Efficient Building Design (Chicago: College of Architecture Illinois Institute of Technology) (2003) Introduction to Architectural Science The Basis of Sustainable Design Second Edition, Steven V. Szokolay (Oxford: Architectural Press) (2008) http://www.bbc.co.uk/weather/2643743 Climate Consultant 5.4 (2012) US Department of Energy Energy Efficiency & Renewable Energy http://apps1

We calculated the monthly temperatures and used Auliciems psycho-physiological model to calculate the comfort limits for the office.

Comfort indices, comfort zone Comfort limits are set between 19°C and 22°C for commercial offices. Once calculating the temperature difference between the average monthly temperature and the minimum comfort level.

By analysing the solar geometry we were able to calculate the times of year when lighting will be on and in which parts of the building. Facade design will play a crucial role in regulating the indoor climate and balancing solar gains, internal gains and ventillation rates with an aim of mnimising the heating and cooling loads on the HVAC system.

Weather data can be summarised in these categorised as; 1 Temperature, measured in the shade 2 Humidity 3 Air movement i.e. wind, normally measured at 10 m above ground in open country, but higher in built-up areas, to avoid obstructions; both velocity and direction are recorded.

4 Precipitation, the total amount of rain, hail, snow or dew, measured in rain gauges and expressed in mm per unit time (day, month or year).

Environment and climate conditions

Psychrometry and HDD

Occupancy scheduling & lighting

Internal gains

Comfort indices

A6.2

Main Considerations

A6.1

Conclusions

Building design methodology

A6

Appendices Derived Data – Degree Days Is the cumulative temperature deficit below a set base temperature (Tb) multiplied by time We would normally see this information provided as HDD per month If we use the mean outside temperature of the day HDD = Σ(T base – T mean of the day) Base Temperature for the UK is 15.5°C for normal buildings

AT3 Part 2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

If the average outside temperature over 24hs (1 day) falls by 1°C below 15.5 °C we accumulate 1 degree day Derived Data - Degree Hours If we have more detailed information we use hourly outside temperatures and calculate Heating Degree Hours HDH = Σ(T base – T hourly ) Base Temperature for the UK is 15.5°C for normal buildings I.e. every time the outside temperature falls by 1°C below 15.5 °C for 1h we accumulate 1 degree hour This concept is useful to estimate annual and monthly heating demands on your designs, i.e. a large HDD in a month would indicate the building design would have to consider how to deal with this period Quantities HDD will give you an indication of what kind of weather you are dealing with in a more quantitative basis.

Although CDD (Cooling Degree Days) can be calculated in the same way but using a higher base temperature, they are not as reliable because the following parameters cannot be reasonably approximated:

B1

B2

Internal Gains Distribution, Environmental Analysis and Building Performance Criteria Group 23 Thomas Wakeman, Clarissa Evans, Anna Ronayne Speculative Office Building, 1 Kingsway, Cardiff

AT3 Part 2