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GUIDELINES ON ENERGY CONSERVING DESIGN OF BUILDINGS - 2020 EDITION
Section I. Purpose
1.1 To encourage and promote the energy conserving design of buildings and their

services to reduce the use of energy with due regard to the cost effectiveness, building
function, and comfort, health, safety, and productivity of the occupants.

1.2 To prescribe guidelines and minimum requirements for the energy conserving design
of new buildings and major renovation of existing buildings that fall and are covered
under these guidelines and provide methods for determining compliance with the same
to make the buildings always energy-efficient.

Section II. Definition of Terms

2. As used in these Guidelines, the following shall mean:

Air — refers to any of the following:

Ambient Air — air surrounding a building; the source of outdoor air brought into a
building.

Exhaust Air — air removed from a space and discharged to outside the building by
means of mechanical or natural ventilation.

Indoor Air — air in an enclosed occupiable space.

Outdoor Air — ambient air that enters a building through a ventilation system, through
intentional openings for natural ventilation, or by infiltration.

Return Air — air removed from a space to be recirculated, or exhaust air.

Supply Air — air delivered by mechanical or natural ventilation to a space and
composed of any combination of outdoor air, recirculated air, or transfer air.

Ventilation Air — supply air that is outdoor air plus any recirculated air that has been
treated for the purpose of maintaining acceptable Indoor Air Quality.

' Air Conditioning — the process of treating air so as to control simultaneously its temperature,
humidity, cleanliness, and distribution to meet the requirements of conditioned space.

Air Handling Unit ~ a device used to regulate and circulate air through a duct as part of an
air conditioning system.

American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE)
— global society founded in 1894, advancing human well-being through sustainable technology
for the built environment with focus on building systems, energy efficiency, indoor air quality,
refrigeration, and sustainability within the industry.

Best Efficiency Point (BEP) — the point along a pump curve where efficiency is the highest.
it is the factor to properly assess a pump’s operation.

Boiler — a self-contained, low-pressure appliance for supplying steam or hot water.
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British Thermal Unit (BTU) — amount of heat energy needed to raise the temperature of one
pound of water by one degree Fahrenheit.

Building — a permanent structure, whether private or public, enclosed within exterior walls
and a roof, and including all attached apparatus, equipment and fixtures, used for any of a
wide variety of activities, such as dwelling, entertainment, worship, commercial, industrial,
transport, agriculture, public service, education, health care, etc.

Certified Energy Conservation Officer (CECO) — a professional who obtains a certification
as a CECO after demonstrating high levels of experience, competence, proficiency, and
ethical fitness in the energy management profession. The CECO is responsible for the
supervision and maintenance of the facilities of Type 1 establishments for the proper
management of energy consumption and such other functions deemed necessary for the
efficient and judicious utilization of energy.

Certified Energy Manager (CEM) ~ a licensed engineer who obtains a certification as a CEM
after demonstrating high levels of experience, competence, proficiency, and ethical fitness in
the energy management profession, and who is chosen by Type 2 designated establishments
to plan, lead, manage, coordinate, monitor and evaluate the implementation of sustainable
energy management within their organizations.

Coefficient of Performance (COP) — ratio of heating or cooling provided to electrical energy
consumed, where higher COPs equate to lower operating costs.

Color Rendering — the general expression for the effect of the light source on the color
appearance of objects in conscious or subconscious comparison.

Color Rendering Index (CRI) — the measure of the degree of color shift, which objects
undergo when illuminated by the tight source. Values for common light sources vary from 20
to 99. The higher the number, the better the color rendering or color appearance ({i.e., less
color shift or distortion occurs).

Cooling Seasonal Performance Factor (CPSF) — quotient of Cooling Seasonal Total Load
(CSTL) in (kWh) divided by the Cooling Seasonal Energy Consumption (CSEC) in (kWh).

Correlated Color Temperature (CCT) — the absolute temperature (in Kelvin) of the light
source. This indicates visual “warmth” or “coolness.” The chromaticity of general lighting lamps
falls in the range of 2200 to 7500 K. For interior lighting, the chromaticity values of 4000 K and
above are usually described as “cool.” Around 3500 K, light sources have a neutral
appearance but, at 3000 K and below, the lighting effect is usually judged as “warm.” Hence,
the lower the number, the warmer the light (more red content) and the higher the number, the
cooler is the light (more blue content).

Covered Buildings — buildings and their systems, which are still to be constructed or under
construction, or existing buildings and their systems, which are to undergo or is undergoing
expansion and/or modifications, with at least 112.5 kVA of designed total connected electrical
loads or has at least 10,000 square meters (m2) Total Gross Floor Area (TGFA).

Delta Conversion On-Line Uninterruptible Power Supply (UPS) ~ a new technology
introduced to eliminate the drawbacks of the Double Conversion On-Line design and is
available in the range of 5kVA to 1 MW. Similar to the Double Conversion On-Line design, the
Delta Conversion On-Line UPS always has the inverter supplying the load voltage. However,
the additional Delta Converter also contributes power to the inverter output. Under conditions

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of AC failure or disturbances, this design exhibits behavior identical to the Double Conversion
On-Line. In the Delta Conversion On-Line design, the Delta Converter acts with dual purposes.
The first is to control the input power characteristics. This active front end draws power in a
sinusoidal manner, by minimizing harmonics reflected onto the utility. This ensures optimal
conditions for utility lines and generator systems and reduces heating and system wear in the
power distribution system. The second function of the Delta Converter is to charge the battery
of the UPS by drawing power and converting it to the appropriate direct current (DC) charging
voltage.

Design Condition — specified environmental conditions, such as temperature and light
intensity, required to be produced and maintained by a system and under which the system
shall operate.

Designated Establishment — a private or public entity in the commercial, industrial, transport,
power, agriculture, public works and other sectors identified by the Department of Energy
(DOE) as energy-intensive industries based on their annual energy consumption in the
previous year or an equivalent annual index; the amount of consumption as indicated in
Republic Act (R.A.) No. 11285 and subject to adjustment by the DOE as it deems necessary

Department of Energy (DOE) — the agency created through R.A. No. 7638, otherwise known
as the “Department of Energy Act of 1992”, and whose functions were expanded by R.A. No.
9136, otherwise known as the “Electric Power Industry Reform Act of 2001”, R.A. No. 9513,
otherwise known as the “Renewable Energy Act of 2008,” and R.A. No. 11285 otherwise k
own as the “Energy Efficiency and Conservation Act”.

Ductwork — a system of ducts for distribution and extraction of air.

Double Conversion On-Line UPS — the most common type of UPS above 10kVA. In the
Double Conversion On-Line design, failure of the input AC does not cause activation of the
transfer switch, because the input alternating current (AC) is not the primary source, but is
rather the backup source. Therefore, during an input AC power failure, on-line operation
results in no transfer time. The on-line mode of operation exhibits a transfer time when the
power from the primary battery charger battery/inverter power path fails. While a Standby and
Line Interactive UPS will exhibit a transfer time when a blackout occurs, a double conversion
on-line UPS will exhibit a transfer time when there is a large load step or inrush current. This
transfer time is the result of transferring the load from the UPS inverter to the bypass line.
Generally, this bypass line is built with dual Silicon Controlled Rectifiers (SCRs), which are
very fast, so similar to the Standby and Line Interactive UPS, the transfer time is very brief,
usually 4-6 milliseconds. Both the battery charger and the inverter convert the entire load
power flow in this design, which causes reduced efficiency and increased heat generation.

Electric Discharge Lamp — produces light by the passage of an electric current through a
vapor or gas, initiating the discharge to fluoresce or light up. There are two kinds of electric
discharge lamp; Low Intensity Discharge (e.g., Fluorescent) and High Intensity Discharge
(e.g., Mercury vapor, Metal Halide, High and Low Pressure Sodium).

End User — any person or entity requiring the supply and delivery of electricity for its own use.

Energy — the capacity to do work. Energy takes a number of forms that may be transformed
from one into another such as thermal (heat), mechanical (work), electrical and chemical (BTU
or kWh). It refers to all types of energy available commercially, including natural gas (liquid
natural gas and liquid oil gas), all heating and cooling fuels (including district heating and
district cooling), coal, transport fuels, and renewable energy sources.

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Energy Audit — the evaluation of energy consumption and review of current energy cost to
determine appropriate intervention measures and efficiency projects in which energy can be
judiciously and efficiently used to achieve savings. It may refer to a walk-through audit, a
preliminary audit, or a detailed audit.

Energy Conservation — the reduction of losses and wastage in various energy stages from
energy production to energy consumption through the adoption of appropriate measures that
are technologically feasible, economically sound, environmentally friendly, and socially
affordable.

Energy Efficiency — the way of managing and restraining the growth in energy consumption
resulting in the delivery of more services for the same energy input or the same services for
less energy input.

Energy Efficiency Class (EEC) — the level of the product’s class, which is based on the
Cooling Seasonal Performance Factor (CSPF) display on its energy label.

Energy Efficiency Classification — the tiers of EEC according to the ranges of CSPF.

Energy Efficiency Ratio — the ratio of net cooling capacity (BTU per hour) to total rate of
electric input (Watt) under designated operating conditions.

Energy Recovery — includes any technique or method of minimizing the input of energy to an
overall system by the exchange of energy from one sub-system of the overall system with
another.

Energy Recovery Ventilation System — a device or combination of devices applied to
provide the outdoor air for ventilation, in which energy is transferred between the intake and
exhaust air stream.

Enthalpy Recovery Wheel — an energy recovery device that transfers outgoing or exhaust
air, i.e. temperature and humidity, to the incoming outdoor air.

Equivalent Temperature Difference (TDeq) — the temperature difference which results in
the total heat flow through a structure as caused by the combined effects of solar radiation
and outdoor temperature.

Green Energy Option Program (GEOP) — a mechanism to empower end users to choose
renewable energy (RE) in meeting their energy requirements.

Heating, Ventilating and Air Conditioning (HVAC) — system that helps maintain good indoor
air quality through adequate ventilation with filtration and provide thermal comfort.

Iuminance (E) — a measure of the amount of light falling on a surface. It is the average
illumination of a surface and its unit of measure is Lux (Ix) = Im/m2.

Incandescent Lamp — produces light by the passage of an electric current through a filament,
which heats it to incandescence (e.g., tungsten and tungsten-halogen).

Indoor Environmental Quality (IEQ) — condition inside the building that includes air quality,
access to daylight and views, pleasant acoustic conditions, and occupant control over lighting
and thermal comfort.

Line Interactive UPS — the most common design, where the battery-to-AC power converter
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(inverter) is always connected to the output of the UPS. Operating the inverter in reverse
during times when the input AC power is normal provides battery charging. When the input
power fails, the transfer switch opens and the power flows from the battery to the UPS output.
With the inverter always on and connected to the output, this design provides additional
filtering and yields reduced switching transients when compared with the Standby UPS
topology. In addition, the Line Interactive design usually incorporates a tap-changing
transformer. This adds voltage regulation by adjusting transformer taps as the input voltage
varies. However, the inverter can also be designed such that its failure will still permit power
flow from the AC input to the output, which eliminates the potential of single point failure and
effectively provides for two independent power paths. This topology is inherently very efficient
which leads to high reliability while at the same time providing superior power protection.

Luminaire Efficiency — the ratio between the luminous flux emitted by the luminaire and the
luminous flux of the lamp (or lamps) installed in the luminaire.

Luminance (L) — the brightness of an illuminated or luminous surface as perceived by the
human eye and its unit of measure is cd/m2.

Luminous Efficacy (n) — the efficiency with which the electrical power consumed is converted
into light and its unit of measure is Im/W.

Luminous Flux (#) — the light output of a light source and its unit of measure is Lumen (Im).

Luminous Intensity ({) — the measure of light output in a specified direction and the unit of .
measure is Candela (cd).

Mechanical Ventilation — ventilation provided by mechanically powered equipment such as
motor-driven fans and blowers but not by devices such as wind-driven turbine ventilators and
mechanically operated windows.

Minimum Energy Performance ~ a performance standard which prescribes a minimum level
of energy performance for the commercial, industrial and transport sectors, and energy
consuming products including appliances, lighting, electrical equipment, machinery and
transport vehicles that shall be met or exceeded before they can be offered for sale or used
for residential, commercial, transport, and industrial purposes.

Natural Ventilation — ventilation provided by thermal, wind, or diffusion effects through doors,
window, or other intentional openings in the building.

Net Metering — a system, attributed to distributed generation, in which a distribution grid user
has a two-way connection to the grid and only charged for his net electricity consumption and
is credited for any overall contribution to the electricity grid.

Overall Thermal Transfer Coefficient (OTTC) — thermal performance of the building
envelope (walls or roof) considering all types of thermal transfer.

Pump -~ a rotating machine consisting of an impeller, a pump casing, bearings, bearing frame,
shaft and a mechanical seal. The operating principle is to convert mechanical energy to
pressure. The pump impeller accelerates a liquid and as the area of the pump casing expands,
the velocity of the fluid is converted to pressure. As a result, pressurized fluid exits the pump
discharge. Pump is basically an electro-mechanical device.

Renewable Energy (RE) Resources — energy resources that do not have an upper limit on
the total quantity to be used. Such resources are renewable on a regular basis, and whose
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renewal rate is relatively rapid to consider availability over an indefinite period of time. These
include, among others, biomass, solar, wind, geothermal, ocean energy, and hydropower
conforming with internationally accepted norms and standards on dams, and other emerging
renewable energy technologies.

Renewable Portfolio Standards (RPS) — a market-based policy that requires electricity
suppliers to source an agreed portion of their energy supply from eligible RE resources.

Seasonal Energy Efficiency Ratio (SEER) — energy efficiency rating for central air
conditioners.

Solar Factor — the factor for vertical surfaces, which has been experimentally determined for
this geographical zone.

Solar Heat Gain Coefficient (SHGC) of Glazing ~ the ratio between the incoming solar
radiation behind a glazing and the incoming solar radiation in front of a glazing.

Standby-Ferro UPS — was once the dominant form of UPS. This design depends on a special
saturating transformer that has three windings (power connections). The primary power path
is from AC input, through a transfer switch, through the transformer, and to the output. In the
case of a power failure, the transfer switch is opened, and the inverter picks up the output
load. In the Standby-Ferro design, the inverter is in the standby mode, and is energized when
the input power fails and the transfer switch is opened. The transformer has a special “Ferro-
resonant” capability, which provides limited voltage regulation and output waveform “shaping.”
Even though it is a standby UPS by design, the Standby-Ferro UPS generates a great deal of
heat because the Ferro-resonant transformer is inherently inefficient. The principal reason why
Standby-Ferro UPS systems are no longer commonly used is that they can be fundamentally
unstable when operating a modern computer power supply load: All large servers and routers
use “Power Factor Corrected” power supplies which, when coupled with the Ferro transformer,
can give rise to spontaneous and damaging oscillations.

Standby On-Line Hybrid — the topology used for many of the UPS under 10kVA which are
labeled “online.” The standby DC to DC converter from the battery is switched on when an AC
power failure is detected, just like in a standby UPS. The battery charger is also small, as in
the standby UPS. Due to capacitors in the DC combiner, the UPS will exhibit no transfer time
during an AC power failure. This design is sometimes fitted with an additional transfer switch
for bypass during a malfunction or overload.

Standby UPS — the most common type used for Personal Computers, the transfer switch is
set to choose the filtered AC input as the primary power source (solid line path), and switches
to the battery / inverter as the backup source shall the primary source fail. When that happens,
the transfer switch shall operate to switch the load over to the battery / inverter backup power
source (dashed path). The inverter only starts when the power fails, hence the name
“Standby.”

Steam System — a steam piping system and controls that work together to supply steam or
hot water to heat input devices remote from the Boiler.

Supplier — refers to any person or entity authorized by the Energy Regulatory Commission
(ERC) to sell, broker, market or aggregate electricity to the end users.

Temperature Difference between Exterior and Interior (AT) — the average annual
temperature difference between the outside and inside of an air-conditioned building.

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Type 1 Designated Establishments — are those with an annual energy consumption of
500,000 kilowatt-hours (kWh) to 4,000,000 kWh for the previous year.

Type 2 Designated Establishments — are those with an annual energy consumption of more
than 4,000,000 kWh for the previous year.

Variable Air Volume System — HVAC System that controls the dry-bulb temperature within
a space by varying the volumetric flow of cooled supply air to the space.

Variable Frequency Drive (VFD) or Adjustable Frequency Drive (AFD), Variable-
Voltage/Variable-Frequency (VVVF) drive, Variable Speed Drive (VSD), AC drive, micro
drive or inverter drive — a type of motor drive used in electro-mechanical drive systems to
control AC motor speed and torque by varying motor input frequency and voltage.

Ventilation — the process of supplying or removing air by natural or mechanical means to or
from any space. Such air is not required to have been conditioned. ;

Visible Light Transmittance (VLT) — used to determine the amount of light transmitted
through the glass.

Water Heater — vessel in which water is heated and is withdrawn for use external to the
system.

Section Ill. Application and Exemption
3.1 Application
A. These guidelines are applicable to the design of:

1. New buildings and their systems with at least 112.5 kVA of total connected
electrical loads or has at least 10,000 square meters (m2) Total Gross Floor
Area (TGFA); and

2. Any expansion and/or modification of existing buildings or systems
designed with total connected electrical loads of at least 112.5 kVA or with
at least 10,000 square meters (m2) TGFA.

B. ~ These guidelines shall not be used to circumvent any applicable safety, health
or environmental requirements.

3.2 Exemptions

A. Areas with industrial/manufacturing processes.

PART |
BUILDING ENVELOPE
Section IV. Thermal Performance of the Building Envelope

4.1 Scope

This section is mandatory for air-conditioned buildings. For non-air-conditioned

buildings the requirements defined in this section are not mandatory, but

recommendable to improve thermal comfort. The requirements and guidelines in this
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4.2

section cover external walls, roofs, air leakage and reflectance of the roof.

The thermal requirements shall apply only to air-conditioned buildings. The building
envelope has to be designed to minimize external heat gain, and thereby reduce the
cooling load of the air conditioning system.

The following describes two methodologies to fulfill building envelope requirements in
regard to solar heat load and thermal transmittance: the flexible, but more complex
Overall Thermal Transfer Value (OTTV) method, and the easier to apply prescriptive
method.

OTTV Method

A.

Approach

The solar heat gain through the building envelope constitutes a substantial
share of heat load in a building, which shall have to be eventually absorbed by
the air-conditioning system at the expense of energy input. To minimize solar
heat gain, it is, therefore, the first consideration in the design of an energy-
efficient building. The architectural techniques used to achieve the said
purpose are too numerous to mention. Siting and orientation of a rectangular
building to avoid exposure of its long facades to face east and west, for
instance, is a simple means to reduce solar heat gain, if the building site
permits. Appropriate choice of building shape to minimize building envelope
area and selection of light colors for wall finish to reflect solar radiation are other
common-sense design alternatives to lower solar heat input.

The OTTV concept takes into consideration the three basic elements of heat
gain through the external walls of a building, as follows:

* heat conduction through opaque walls;
° heat conduction through glass windows;
. solar radiation through the glass windows.

‘These three basic elements of heat input are averaged out over the whole

envelope area of the building to give an overall thermal transfer value, or OTTV
in short. This concept, in essence, helps to preserve a certain degree of
flexibility in building design.

Facade

For the purpose of energy conservation, the maximum permissible OTTV has
been set at 45W/m?.

To calculate the OTTV of an external wall, use the basic formula below:

OTTV = (Aw x Uw x TDeq) + (Af x Uf x AT) + (Af x SHGC x f x SF)

Ao
Where:
OTTV: overall thermal transfer (W/m?)
Aw: opaque wall area (m7)
Uw: thermal transmittance of opaque wall (W/m?K)

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1.

TDeq: equivalent temperature difference (K), see sub
paragraph 1)

Af: fenestration area (m2)

Uf: thermal transmittance of fenestration (W/m?)
AT: temperature difference (K) between exterior and
interior, see sub paragraph 2)

f: SHGC correction factor f of shading device, see
sub paragraph 3)

SHGC: solar heat gain coefficient of glazing, see sub
paragraph 4)

SF: solar factor (W/m?), see subparagraph 5)

Ao: gross area of exterior wall (m2) = Avs + Af

Equivalent Temperature Difference (TDeq)

Equivalent Temperature Difference (TDeq) is the temperature difference
which results in the total heat flow through a structure as caused by the
combined effects of solar radiation and outdoor temperature. The TDeq
across a structure takes into account the types of construction (mass and
density), degree of exposure, time of day, location and orientation of the
construction and design condition.

For the purpose of simplicity in OTTV calculation, the TDeq of different
types of construction have been narrowed down to three values according
to the densities of the constructions, as given in Table 7.

Table 1; Equivalent Temperature Difference for Walls

Wall Construction
Mass Per Unit Area

9 25 5 kg ra?

126. 195 kegir rer

Above 195 kg/m

Source: Guidelines on Energy Conserving Design of Buildings, 2007
Temperature Difference between Exterior and Interior AT

The temperature difference between exterior and interior AT is the average
annual temperature difference between the outside and inside of an air-
conditioned building, and is required for calculation of the heat conduction
through glazing. In contrary to the equivalent temperature difference TDeq,
AT does not consider solar radiation and is therefore with 5 K significantly
lower.

Correction Factor for the Shading Device

The correction factor f is the ratio between the incoming solar radiation
behind a shading device and the incoming solar radiation in front of a
shading device and is therefore between 0 (opaque) and 1 (no shading).
The correction factor can be derived from literature values, manufacturer
data, simulation or calculation as shown in Subsection 4 on shading

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devices).
4. Solar Heat Gain Coefficient SHGC of Glazing

The solar heat gain coefficient is the ratio between the incoming solar
radiation behind a glazing and the incoming solar radiation in front of a
glazing. The solar heat gain coefficient can be derived from manufacturer
data.

5. Solar Factor (SF)

' The Solar Factor for vertical surfaces has been experimentally determined
for this geographical zone. From data collected over a period of time for the
eight primary orientations, the average Solar Factor for vertical surfaces
has been worked out to be 130 W/m*. This figure has to be modified by a
correction factor when applied to a particular orientation, and also if the
fenestration component is sloped at an angle skyward. For the purpose of
the building regulations, any construction having a slope angle of more than
70° with respect to the horizontal shall be treated as a wail. For a given
orientation and angie of slope, the Solar Factor is to be calculated from the
following formula:

SF: 130 x CF (W/m?)

Where CF is the correction factor with reference to the orientation of the
facade and the pitch angle of the fenestration component and is given in
Table 2.

Table 2: Solar Correction Factor Wall

Slope Angie

Notes The correction facters fer iter uricntalaers ened other patty oangles are pour by
torte preideel satrt.
Source: Guidelines on Energy Conserving Design of Buildings, 2007

As walls at different orientations receive different amounts of solar
radiation, it is necessary in general to compute first the OTTVs
individual walls, then the OTTV of the whole building envelope. The
latter is obtained by taking the weighted average of these values. To
calculate for the envelope of the whole building, use the formula below:

OTTV = Ao1 X OTTV + + Ag2 X OTTV2 +... +Acx X OTTV,
Aoi + Ao2 + ... + Aox
The gross area of an exterior wall shall include all opaque wali areas,
window areas and door areas, where such surfaces are exposed to
outdoor air and enclose an air-conditioned space. The fenestration area
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shall include glazing, glazing bars, mullions, jambs, transoms, heads
and sills of window construction and shall be measured from the
extreme surfaces of the window construction.

Where more than one type of material and/or fenestration is used, the
respective term or terms shall be expanded into sub-elements, such as:

(Aw; x Uw: x TDeq:) + (Aw2 x Uwe x TDeqz), etc. -

In the case of a mixed-use building where the residential portion and
the commercial portion are distinctly and physically separated from
each other, e.g., in the form of a residential tower block and a
commercial podium, the OTTVs of the two portions shall be separately
computed.

Roof

For an air-conditioned building, solar heat gain through the roof also constitutes
a substantial portion of the cooling load. From on-site solar radiation
measurements taken, the intensity of the radiation on a horizontal surface can
be as much as 3 times of that on a vertical surface.

The purpose of roof insulation is therefore two-folds: to conserve energy in air-
conditioned buildings and to promote thermal comfort in non-air-conditioned
buildings. In both cases, the building regulations require that the roof shall not
have a thermal transmittance or U-value greater than the values tabulated in
Table 3.
Table 3: Maximum U-value for Roof
Se

Maximum Thermal
TransmitZtance (Wim? K}

Air-conditioned
Building

50 to 230

Weight Group

Non air-conditioned
Builcling

fight — under 50

mediunt

aver 230

heavy

Source: Guidelines on Energy Conserving Design of Buildings, 2007

In the case of an air-conditioned building, the concept of OTTV is also
applicable to its roof if the latter is provided with skylight. Otherwise, refer to
the chapter with the prescriptive method. The OTTV concept for roofs takes
into consideration three basic elements of heat gain, as follows:

e Heat conduction through opaque roof,
e Heat conduction through skylight;
e Solar radiation through skylight.

The maximum permissible OTTV for roofs is set at 45 W/m?.

To calculate the OTTV of a roof, use the same basic OTTV formula for building
facade described earlier.
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For the purpose of simplicity in OTTV calculation, the TDeq of different types
of roof constructions have been standardized in Table 4.

Table 4: Equivalent Temperature Difference for Roof

> Wall Construction
Mass Per Unit Area. -

O- SOkgim’?

51. 230 kim’

Ove: 330 kgin’

Source: Guidelines on Energy Conserving Design of Buildings, 2007

Since a roof is more exposed to the sun than a facade, the following solar factor
has to be applied for roofs:

SF: 320 x CF (Wim?)

Where CF is the correction factor with reference'to the orientation of the roof
and the pitch angle of the skylight component and is given in Table 5.

Table 5: Solar Correction Factor for Roof

Orientation

Stope Angie

noo |
103 103 54

103 | 3
rT ~ ai ~ ” { 4
1S 103 | 105 | 103 | 103 |

103 101 | 703 | ;

Fogo | 103 |

—-4 +-

{
i 3
+ a eee + nn ee ~-4
i 1Oh | GF TO: 1.08 ior}
OSS a4 ogg | i

O92 '

—~ + + 4
50" | 0.81 | 089 | 095 | O89 | O83 | O89 | 095 | O89 |
ae ce ee San ee ee Cn bree a ee
55" | 077 Osa | 0.91 | O85 | 078 02s | 0% i O84 |
60" | O71 | OBS | OBE | O80 | O73 | OBG | O86 | a7a |
: Hy i Hl
cn cterew ernest antennae eu fuera nannies tata at nme nn ian ean loeieeenenie manana » cae: Si |
6s" [986 | 074 ; 081 | O78 | 067 | O75 | O81 | O74 |
oo [ae ee conn

Source: Guidelines on Energy Conserving Design of Buildings, 2007

Note: See Appendix B to D for sample OTTV calculations, thermal! conductivities, K-values, and glass thermai
transmittance vaiues. :

4.3 Prescriptive Method
A. Solar transmittance of windows

Compared with wall assemblies, glazing transfers more heat, and hence, it is ideal
to reduce the amount of glazing with respect to the wall in order to reduce internal
heat gains.

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The requirement of Window to Wail Ratio (WR) needs to be balanced with the
amount of daylight coming through the glazed area.

Solar Heat Gain Coefficient (SHGC) is used to determine the amount of solar heat
admitted through the glass divided by the total solar radiation incident on the glass.

Visible light Transmittance (VLT) is used to determine the amount of light
transmitted through the glass.

WWAR shall be balanced with SHGCaq to maintain flexibility in design. To explain
further, the higher the designed building WWR, the lower the required SHGCaq in
glass windows shall be and vice-versa. This does not, however, remove the option
for building owners to apply windows with low SHGCag for building with low WWR.
The size of the opening (with or without glass) shall be in accordance with the
National Building Code (NBC),

For each WWR value, the SHGCag shall be in accordance with Table 6. The
SHGCag requirement in Table 6 can be adjusted if sun breakers are provided in
the windows. A sun breaker plays an important role in reducing solar heat gain as
it stops solar radiation before it enters the building, and doing so reduces the
cooling loads considerably. External shading has the additional positive effect of
improving the internal comfort, cutting part of the direct radiation on occupants.
This shall be applied only to shaded windows.

Table 6: SHGCag for different WWR

Maximum
SHGCay

Source: Prescribed Requirements, IFC Philippine Green Building Code Project, May 2013
SHGCagj limits can be adjusted by multiplying it with the correction factors
using the formula:
SHGCag = SHGC x f
where:

SHGC is the adjusted solar heat gain coefficient limit for windows with
external shading

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4.4

SHGC is the solar heat gain coefficient of the glazing

fis the SHGC correction factor f of the shading device. If there is no shading
device, f can be set to 1.

SHGC is the solar heat gain coefficient of the glazing and can be derived from
the manufacturer data. fis the SHGC correction factor f of the shading device
and can be derived by the manufacturer data, simulation, or simplified
calculation as described in the next subsection on shading devices.

B. Minimum Insulation Values

Insulation helps to reduce heat gain in a building, thus improving thermal comfort,
acoustic quality, and reducing the load on the air conditioning system. Buildings
shall be provided with roof insulation so that the average U-value is maximum 1.4
Wim?Kand the average U-value of the wall is maximum 3.4 W/m?K.Skylights shall
have an opening ratio of maximum 5% related to the floor area of the room
beneath.

Shading Devices and Determination of the Shading Coefficient

Shading devices, especially when installed externally, can help improve thermal
comfort and significantly reduce energy consumption due to air conditioning in a
building. The effectiveness of the shading device is defined by the correction factor f,
which is the ratio of solar radiation behind and in front of a shading device. Hence f =
1 if there is a window without shading and f = 0 if the window is opaque.

Given the huge variety of shading devices, and hence f factors, take the following into
account when determining the f factor: ;

1. manufacturer data
2. simulation
3. calculation

One of the most energy- and cost-efficient possibilities for external shading in tropical
countries is the fixed overhang and vertical fin. To encourage the provision of sun-
shading devices to improve thermal comfort and reduce energy demand, the building
regulations make a special provision to relax the requirement pertaining to boundary
clearance. Where overhangs, canopies, awnings, or other sun-shading devices are
provided, these devices are permitted to project up to a point not less than 1600 mm
from the lot boundary instead of the normal requirement of 2300 mm for boundary
clearance.

To take advantage of this relaxation, the designer shall ensure that only non-
combustible materials are used for the construction of the shading devices. It should
be noted that the relaxation is only in respect to the projection of shading devices; wall
designs shail still comply with the normal boundary clearance requirement.

To simplify the determination Process, the f factor for these shading types can be
calculated as follows:

First, the depth of the overhang or the vertical fin has to be calculated. Second, the

height of the window (including the distance between the top part of the frame and the

overhang), or the width of the window (including the distance between the frame and’
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45

the fin), have to be calculated.
Figure 1: Schematic Representation of a Window and Related

Horizontal Overhang or Vertical Fin
DEPTH

HEIGHT
WIDTH

Based on the ratio between the depth of shading and the height/width of window, the
correction factor f can be selected from Table 7.

Table 7: Correction factor f for external fixed shading

Depth/Height ' SHGC Correction Factor f

Horizontal Shading Vertical Shading

ot , pee nat em tncnennene cen

Source: Results of EU-ASEP simulation, 2020

Airtightness of the Building Envelope

The infiltration of warm air and moisture and exfiltration of cold air contribute
substantially to the heat gain and energy consumption of an air-conditioned building.
Also, warm and humid air can cause condensation in the building construction and
subsequently lead to mold growth and health problems of the building occupants.

As a basic requirement, buildings shall not have unenclosed doorways, entrances,
etc.; where heavy traffic of people is anticipated, self-closing doors shall be provided.
The concept of an energy-efficient building is based on the assumption that the
envelope of the building is completely enclosed to minimize the infiltration of warm air
and exfiltration of cool air. Infiltration and exfiltration contribute substantially to the
building's heat gain, as the warmer infiltrated air shall be cooled in order to maintain
the desired comfort condition.

To further minimize the exfiltration of cool air and infiltration of warm air and moisture
through leaky windows and doors, effective means of weather-stripping shall also be.
incorporated. Additionally, building envelope enclosures such as walls, roofs, and
floors on grades shall be non-permeabie to prevent the infiltration of moisture.

Preferably, doors and windows shall be designed to meet the following criteria when
tested under a pressure differential of 75 Pa:

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4.6

4.7

1. Windows: leakage to limit to 2.77 m*/h per meter of sash crack
2. Swinging revolving or sliding doors: leakage to limit to 61.2 m3/n per meter
of door crack

3. Air curtains may be used in very high-volume entrances only when
revolving or self-closing sliding doors and vestibules are not appropriate.

4. Entrance vestibules, airlocks, and anterooms shall have at least 3 meters
depth/run before the next set of doors.

5. Entrances shall have auto door closers on air locks to keep cold air in and
warm air out.

Reflectance of the Roof

A light-colored building envelope, especially the roof areas which are the most
vulnerable, can reduce heat transfer from the outside to the inside of the building by
having surfaces with high Solar Reflectance Index (SRI).

Roofs shall have one or a combination of the following measures:
1. Roof color with a minimum average SRi of 70
2. More than 70 % of the roof is back ventilated.
3. More than 70 % of the roof is covered by solar thermal and/or PV..
4. More than 70% is covered by a green roof.

Required Design Documentation
The following documents shall be required for the building permit application:
A. Architectural drawings:

e Floor plans with the supporting details and information to satisfy the
requirements of this section

e Elevations with the supporting details and information to satisfy the
requirements of this section

e Sectional drawings with the supporting details and information to satisfy
the requirements of this section

B. Material specifications, e.g. in tender documents or detailed drawings:

Windows, skylights: U-value, SHGC value

Walls: material type, thickness, k-values

Roofs: material type, thickness, k-values

Shading: shading length, f-value

Insulation specifications supporting wall and roof k-values

Roof deck, wall, and floor specification on non-permeable coating

C. Proof/Evidence of building envelope compliance

OTTV method: OTTV calculation for wall and roof
Prescriptive method: calculation of window-to-wall ratio
SHGC of glass window to be used

Proposed Roof U-value computation

Proposed Wall U-vaiue computation

Skylight area and roof area computations

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5.1

5.2

e Proposed methods and materials for building airtightness
e Proposed SRI of the roof

PART Il
MECHANICAL SYSTEMS
Section V. Air Conditioning and Ventilating System
Scope

The requirements in this section represent minimum design criteria. Designers shall
evaluate other energy conservation measures, which may be applicable to the
proposed building or the proposed building renovations. The Philippine Green Building
Code (PGBC) applies to all new construction and/or alteration of buildings with a Total
Gross Floor Area (TGFA) of 10,000 square meters (m*) or more. In case of conflict
between the provisions of the PGBC and these guidelines, the most stringent
requirement shall apply.

Building owners with buildings with a TGFA of 10,000 m? or more shall be required to
submit the building’s annual electricity usage (kWh/year), fuel consumption (liters/year)
of generators, and liquefied petroleum gas (LPG) consumption (kg/year). This shall
be submitted in the application for the renewal of mechanical systems. Document to
be submitted in the report shail be the monthly electrical bills, fuel, and LPG delivery
receipts.

Load Calculation
A. Calculation Procedures

Cooling system design loads for the purpose of sizing the system and equipment
shall be determined in accordance with the procedures in the latest edition of the
ASHRAE Handbook of Fundamentals or other equivalent publications.

B. Indoor Design Conditions
The indoor conditions in an air-conditioned space shall conform to the following:

Design Dry Bulb Temperature 25°C
Design Relative Humidity 55%
Maximum Dry Bulb Temperature 27°C
Minimum Dry Bulb Temperature 23°C
Maximum Relative Humidity 60%
Minimum Relative Humidity 50%

OuRON >

Note: Indoor design conditions may differ from those presented above because of special occupancy or
process requirement, source control, air contamination, or local regulation.

C. Outdoor Design Conditions
The outdoor conditions shall be taken as follows for Climate Zone OA:

1. Design Dry Bulb Temperature 35°C
2. Design Wet Bulb Temperature 28°C

Notes: See ASHRAE Standard 169-2013 Table A-6 on Philippine Cities Climate Zone in the Appendix

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5.3

D. Ventilation

The quality and quantity of air used to ventilate air-conditioned spaces shall always be
sufficient and acceptable to human occupation and comply with applicable health
and/or air quality requirements. Ventilation requirements shall conform to the design
criteria in Table 76.

Exception: Outdoor air qualities may exceed those shown in Table 17 because of
special occupancy or process requirements, source control air contamination or local
regulations.

E. Kitchen Ventilation

Figures 4 through 9 show the six basic hood styles for Type 1 applications. The style
names are not used universally in all standards and codes but are well accepted in the
industry. The styles are as follows:

1. Wall-mounted canopy — Used for all types of cooking equipment located
against the wall (See Figure 4)

2. Single-island canopy — Used for ail types of cooking equipment in a single-
line island configuration (See Figure 5)

3. Double-island canopy — Used for all types of cooking equipment mounted
back to back in an island configuration. (See Figure 6)

4. Back shelf — Used for counter-height equipment typically located against
the wali, but could be freestanding. (See Figure 7)

5. Eyebrow — Used for direct mounting to oven and some dishwashers. (See
Figure 8)

6. Pass-over — Used over counter-height equipment when pass-over
configuration (from the cooking side to the serving side) is required. (See
Figure 9)

System Design and Sizing

Air conditioning system and equipment shall be sized as close as possible to the space
and system loads calculated in accordance with the subsection on load calculation.
The design of the system and the associated equipment and controls shall take into
account important factors such as nature of application, type of building construction,
indoor and outdoor conditions, internal load patterns, contro! methods for efficient use,
and economic factors.

A. Engineered systems and equipment shall be properly sized and selected to meet
maximum loads and shall have good unloading characteristics to meet the
minimum load efficiency. These shall be arranged in multiple units or increments
of capacity to meet partial and minimum load requirements without short cycling.

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Table 8: Number of Chillers and Water Chiller Types

| Table 1.422 Numbor of Critters

ae Total Chiller Plant Gapacty “Mumber of Chien j

Ht ans, Cee

Ee UY

iad gas, “Pant miner atthe chats gatest ecctial eechebes a. fargqer vran BOO cans gf suseet osjuatly:

Tabie 19.8.2-3 Water Cheiter Types

ieedividual Chillar Plant Capenity Elecite Chiller Type | Foss Fisgl ChRter Typa }

re Fert Sigdeallert a an brent fre

elas feos

fA ore. Sartre eget Cyatitbe ate eanpame ghraet fev

Source: ASHRAE 90.1-2019

General Notes for Number of Chillers: If the total capacity of the chilled water requirement is over 2,400 TR
(8,450 kW), the sizing would be at the discretion of the designer. VFD drive would only be required for units
that would be doing peaking loads. Baseload chillers would be soft-starter drive.

Table 9: Energy Utilization Index Comparison

Energy Utilization indax comparison {RWhISQ eve)

Buiiding Use | IFC-PGBI EDGE Philigpine GB ZERO Canto
Survey Philippines Cade Min. jdcrwed from
2013 Baseline Compliance ASHRAE 904-2076

tEDGE (Calc}

| Office i 345 3

Min. Comphancet

[ Residential 65
Condo

1 Hospital S35
Hotcl

{ Schoo! _

i Retail (Mall}

Source: iFC/Green Building Code Survey

Table 10: Climate Zone
latte 4201.1 Gending Performance Facter QOTs
ke a

Aron Trine
Waiters RAG TTD Sh OF GeO GRA AG Hee DPR asa Oa nese ars

Deeg theirs Pe GED GSH St SR TBE aR SA Gd baa GAT AP AAA Sa Ag
hoapitat

Payee tated rosa ss Re

1 Atha Grete Ol baw 08

Restores Cat 04H GAS GRE Ty
TRE Pea SP PS PR OS OO Ah TERR PD OAD PAR Gr

ay O47 FOF Tat GIR OFF PAG FAR Ta AT BoA at
Macatee s suangen HSS Teds Sn AP RAR Dad SD A AS Fae Oe OAS RAR Tha Rt AT GAT

Ab gras CSR CPST COA Pe BS Bd TrGY RAS 1G Ueha OAL At FRA OF Oe rap nar

Source: ASHRAE 90.1-2019

Considerations shall be given at the design stage for providing centralized
monitoring and control to achieve optimum operations with minimum energy
consumption.

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5.4

5.5

Fan System Design Criteria

A. General

The following design criteria apply to all air conditioning fan systems used for comfort
ventilating and/or air conditioning. For the purpose of this section, the energy demand
of a fan system is the sum of the demand of all fans required to operate at design
conditions to supply air from the cooling source to the conditioned space(s), or exhaust
it to the outdoors.

Exception: System with a total fan motor power requirement of 5 kW or less.

B. Constant Volume Fan Systems

For fan systems that provide a constant air volume whenever the fans are operating,

‘the power required by the motor of the combined fan system at design conditions shall

not exceed 0.5 W/ m*/h.
C. Variable Air Volume (VAV) Fan Systems

1. For fan systems that are able to vary system air volume automatically as a function
of load, the power required by the motor of the combined fan system at design
conditions shall not exceed 0.5 W/m3/h.

2. Individual VAV fans with motor rated at 5 kW and larger shall include control and
devices such as a variable speed drive necessary to make the fan motor operate
efficiently even at flow rates of as low as 40% of the rated flow. Electronically
commutated (EC) motors shall be used.

Pumping System Design Criteria
A. General

The following design criteria apply to all pumping systems used for comfort air
conditioning. For the purpose of this section, the energy demand of a pumping system
is the sum of the demand of all pumps required to operate at design conditions to
supply fiuid from the cooling source to the conditioned space(s) and return it back to
the source. Pumps doing the peaking load shall have VFD drives.

Exception: System with total pump motor requirement of 5 kW or less

B. Pressure Drop

Chilled water and cooling water circuits of air conditioning systems shall be designed
at a maximum velocity of 1.2 m/s (3.9 fps) for a 50 mm diameter pipe and pressure
drop limit of 39.2 kPa per 100 (4 ft/100 ft) equivalent meter for piping over 50 mm

diameter. To minimize erosion for the attainment of the piping system, the water
velocities found in Table 20 shall not be exceeded.

Page 20 of 74