Heat Loss in the home

Report
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• The Regulator (NRCS) has published legislation regarding energy
efficiency in new buildings (NBR-XA)
• Here’s what you need to know for your home
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• South Africa’s mounting energy crisis means that we all need to think of
innovative ways to save electricity in our homes and of products that can help
you reduce our current electricity usage.
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• The application of this new regulation is good news for the environment and will
help you save electricity.
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• The National Building Regulation (NBR) has been updated to include Part X which
addresses environmental sustainability and Part XA which establishes
requirements for energy efficiency in new buildings.
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• The National Standard SANS 10400 (building code) is made up of various parts.
Parts A to W are deemed to satisfy rules which, if adhered to, will ensure
compliance to the National Building Regulations. Each part covers different
aspects of the construction and finishing of buildings. These are the minimum
standards that ensure the health and occupational safety of the occupants in
these buildings.
Heat Loss in the home
Buildings typically account for 40% of all energy consumed in South Africa and yet
their potential to save energy is huge.
Thermal insulation must be included in the design of all new buildings. This, in
combination with energy saving techniques, makes it possible to save up to 78% of a
building’s energy consumption for space heating, cooling and hot water services.
40% of SA total energy currently used in
buildings
≈ 35% Roof
Summer
≈ 10% Air
gaps
≈ 25%
Walls
Thermal
bridges
Glazing
Floor
≈ 10%
Principle of
insulation
Winter
≈ 10%
≈ 10% Ground
Correctly insulating the building envelope in combination with energy saving techniques can
control energy losses and reduce energy consumption by up to 78%
There are three ways of complying with the
energy regulation.
Option 1:
Comply with the SANS 10400-XA requirements
•Otherwise described as “Deemed to Satisfy”
Option 2:
Rational design
•This option requires input of a relevant professional
•Thermal performance of building needs to be calculated
•Performance should be equal to or better than SANS 10400-XA
Option 3:
Comparison with a compliant theoretical building
•Comparison with the design performance of a “notional” building
•Notional building should be designed to “Deemed to Satisfy”
standards
•Thermal performance calculations software used must be approved
by Agrément SA
Climatic zones – South Africa
South Africa has been divided into six climatic zones according to their
humidity and temperature
Zone
Climatic conditions
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Zone 1
Cold Interior
•Zone 2
Temperate Interior
•Zone 3
Hot Interior
•Zone 4
Temperate Coastal
•Zone 5
Sub-tropical Coastal
•Zone 6
Arid Interior
Drg.727a
Drg.727a
• An important consideration when building is to determine
the relevant climatic zone. Each of the climatic zones has a
different R-value requirement for certain walls and ceilings.
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• Insulation R-value should be indicated on the packaging.
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• All material has an R-value which is the ability of a product
to resist the transfer of heat. Thermal insulation provides a
high resistance to the flow of heat from the warm surface
to the cold surface in your home, helping you maintain a
comfortable living environment, keeping your house cool in
summer and warm in winter.
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Requirements to comply with SANS 10400-XA “Deemed to Satisfy”
Building envelope requirements (SANS 10400-XA)
>> Orientation (Guideline)
Compact in plan with most glass on the northern sied
Living spaces on northern side
Longer axis of dwelling to be east-west
Roof overhang to shield northern windows in midday summer sun
>> Floors
If under floor heating is installed the floor slab must be insulated with insulation with a minimum
R-value of 1.00
>> Fenestration (Windows/Glass doors/Skylights)
Buildings with up to 15% fenestration area per storey
Buildings with fenestration area per storey exceeding 15% shall comply with the requirements for fenestration in SANS
204
Air leakage should comply with SANS 613
>> External Walls
Light weight (Non brick/Non concrete) walls must achieve a minimum R-value:
Of 2.2 for climatic zones 1 & 6
Of 1.9 for climatic zones 2, 3, 4 & 5
Masonry walls (Brick/Concrete) must achieve a minimum R-value of 0.35
Double skin brick with no cavity, plastered internally and either plastered externally or finished with face bricks
Single brick/block with a minimum thickness of 140mm plastered internally and externally
• Hot water supply requirements (SANS 10400-XA)
• Geysers
• A minimum of 50% of the annual average heating
requirement for hot water must be provided by means
other than electric resistance heating (Geyser) or fossil
fuels
• See options below but not only limited to these:
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Solar Heating
Heat pumps
Geothermal Heat
Renewable Combustible Fuel
Heat recovery from alternative systems and processes
• All exposed hot water pipes ≤ 80mm diameter must be
insulated with a minimum R-value of 1.00
Example of heat flow - Up
For a ceiling in Climatic Zone 1 to meet SANS 10400XA requirements the individual
figures are added together to obtain the total R-value required
SANS 10400 XA – Roof/Ceiling insulation
Roof and Ceilingceiling insulation solution
•Must achieve the minimum total R-value specified below:
•Indicates the direction in which your home loses or gains heat through the roof in each climatic zone.
Isover Aerolite (Flexible Rolls)
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5.5.1 What is an R-Value?
Insulation materials are rated for their performance in restricting heat transfer. This is expressed as the R-Value, also
known as thermal resistance. The R-Value is a guide to its performance as an insulator-the higher the R-Value, the better
the insulation (i.e., resistance to heat flow) it provides.
R-Values are expressed using the metric unit’s m².K/W, where:
• m² refers to one metre squared of the material of a specified thickness;
• K refers to a one degree temperature difference (Kelvin or Celsius) across the material;
• W refers to the amount of heat flow across the material in watts.
Use the nominal R-Values as listed by the manufacturer on the packaging of the insulation to determine the performance.
Products which have the same R-Value will provide exactly the same insulating effect as each other, provided they are
correctly installed. The higher the R-Value the more effective the insulation. Products must be installed in accordance
with the manufacturer’s specifications.
The information available on the product data sheet and/or label must include the R-Value and whether it must be
installed professionally or DIY. Ensure that it suits your particular application. Ask if performance guarantees and/or test
certificates are available.
Material R-Values – the thermal resistance values of bulk/mass type insulation are measured on the product alone
according to international standards.
System R-Values – the thermal resistance value of reflective insulation is calculated based on international standards
and depend on the product being installed as specified in accordance to manufacturer’s specifications. This is known as
a system R-Value which incorporates air spaces.
Composite R-Values - the thermal resistance values of composite insulation products are measured by testing the
composite product as a unit according to international standards.
Direction of heat flow effect
R-Values can differ depending on the direction of heat flow through the product. The difference is generally marginal for
bulk insulation but can be pronounced for reflective insulation.
• Up R-Values describe resistance to heat flow upwards (sometimes known as 'winter' R-Values).
• Down R-Values describe resistance to heat flow downwards (sometimes known as 'summer' R- values).
Integrated Resource Plan
– September 2009
Table 2 – South African generation
capacity assumed for IRP
1.6
Trillion
Integrated resource plan 2009 (DME)
Current installed generation capacity 2010
42 000 MW
Forecast required installed generation capacity 2030
80 000 MW
Of the current installed generation capacity still operation in 2030
10 000 MW
Generating capacity to be installed between 2010-2030
70 000 MW
Equivalent to:
35 Koeberg type Power Stations
or
16 Conventional Coal Power Stations
Minimal CO2 output
(4500MW)
550 MT CO2 output
Compliance
• The provisions of the National Building
Regulations shall be satisfied by:
– Adhering to the requirements of all the prescriptive regulations, or
– Complying with all functional regulations by:
• Adopting building solutions that comply with the deemed to satisfy
requirements of the corresponding part of SANS 10400
• Reliably demonstrating or predicting with certainty that an adopted
building solution has an equivalent or superior performance to a
solution that complies with the deemed to satisfy provisions. (Rational
design by competent person)
Regulatory Framework
• National Building Regulations and Building
Standards Act, 1977 (Act 103 of 1977).
• NBR`s are issued in terms of the above act and
is a compilation of various parts (A to X:–
– Part A – General Principles and Requirements
– Part B – Structural Design
–:
– Part X – Environmental Sustainability
• Part XA – Energy Usage in Buildings
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SANS 10400 is a National Standard: (Building code)
– The Application of the National Building Regulations (also compiled in many parts to
correlate to the National Building Regulations)
Routes to Compliance to NBR-XA
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Option 1: Rational design
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Option 2 – 4 = “Deemed-to-Satisfy”
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Option 2: Compliance to SANS 10400XA
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 This alternative requires input of a professional “competent” person
 Thermal performance of building needs to be calculated
 Performance should be equal or better than specified in SANS 10400XA
 “Recipe” for building elements
 Requirements partially aligned with SANS 204
Option 3: Compliance to Tables
 Thermal performance of building needs to be calculated
 Max Energy Consumption & Max Energy Demand must comply with
tables in SANS 10400-XA
 This alternative requires input of a professional “competent” person
Option 4: Comparison with a compliant theoretical (reference) building
 Building design performance – theoretical max energy consumption &
demand shall be less than or equal to that of a reference building
 Building should be designed to “Deemed to Satisfy” standards
 Use of thermal performance calculations software accredited by
Agrement SA
 This alternative requires input of a professional “competent” person
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Roof and Ceiling
Must achieve the minimum total R-value specified below:
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◦Indicates the direction in which your home loses or gains heat through the roof in each climatic
zone.
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Hot water supply requirements (SANS 10400-XA)
>> Geysers
A minimum of 50% of the annual average heating requirement for hot water must be provided by
means other than electric resistance heating (Geyser) or fossil fuels
See options below but not only limited to these:
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Solar Heating
Heat pumps
Geothermal Heat
Renewable Combustible Fuel
Heat recovery from alternative systems and processes
>> All exposed hot water pipes ≤ 80mm diameter
Must be insulated with a minimum R-value of 1.00
Part XA – Energy Usage in New
Buildings
• XA1 -
In order to contribute to the reduction of greenhouse gases, buildings and extensions to buildings in respect
of which plans and specifications are to be drawn and submitted in terms of the Act, having A1, A2, A3, A4, C1, C2, E1, E2,
E3, E4, F1, F2, F3, G1, H1, H2, H3, H4 and H5 occupancies or building classifications in accordance with Regulation A20,
excluding garage and storages areas contained within such occupancies, shall be designed and constructed so that they :
a)
b)
are capable of using energy efficiently while fulfilling user needs in relation to vertical transport, if any, thermal comfort, lighting and hot
water; or
have a building envelope and services which facilitate the efficient use of energy appropriate to its function and use, internal environment
and geographical location.
Equipment and plant required for conducting the business of the occupant shall be excluded from these requirements .
• XA2 -
At least 50 % by volume of the annual average hot water heating requirement shall be provided by means
other than electrical resistance heating including but not limited to solar heating, heat pumps, heat recovery from other
systems or processes and renewable combustible fuel.
• XA3 -
The requirements of sub-regulation XA1 shall be deemed to be satisfied when such building is designed and
constructed in accordance with the following requirements:
a)
b)
c)
has an orientation of the longest axis, shading, services and building envelope in accordance with SANS 10400-XA; or
is the subject of a rational design by a competent person, which demonstrates that the energy usage of such building is equivalent to or
better than that which would have been achieved by compliance with the requirements of SANS 10400-XA; or
has a theoretical energy usage performance determined using certified thermal calculation software, less than or equal to that of a
reference building in accordance with SANS 10400-XA.
Additional Requirements
• Competent person (where necessary) –
Submit documentation
– Local authority as per SANS 10400-A
• On Plans
– Where provided – location, type & capacity of
water heating installations
– Where provided – details of
• Fenestration
• Insulation
SANS 10400 XA Hot Water Supply –
XA2
• Regulation: A minimum volume fraction of 50%
of the annual average heating requirement for
hot water shall be provided by means other than
electric resistance heating or fossil fuels
including, but not limited to:
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Solar heating
Heat pumps
Geothermal heat
Renewable combustible fuel
Heat recovery from alternative systems and processes
SANS 10400 XA2 Hot Water Supply –
compliance
• The functional requirements of sub-regulation
XA2 shall be satisfied when:
The population for which such building is
designed is determined in accordance with
Regulation A21;
– 4.1.1
The hot water demand is determined in
accordance with table 2 and table 5 of SANS 102521:2004;
– 4.1.2
The storage requirement is based on
maintenance of a hot water temperature of 60 0C;
– 4.1.3
– 4.1.4
Solar water heating systems shall comply with
SANS 10400 XA Geyser systems and Pipe Insulation –
XA 2
1. Roof/Ceiling systems
Requirements
All exposed hot water service pipes shall be clad with insulation with a minimum
R-value in accordance with the table below.
Internal diameter of pipe
Minimum R-value
<80mm
1.0
>80mm
1.5
Determined with a hot surface temperature of 60 °C and an ambient
temperature of 15 °C.
SANS 10400 XA – Geyser and Pipe Insulation
1. Roof/Ceiling systems
Saint-Gobain geyser and pipe insulation solution
1 – Isover Geyser Insulation Pack
(Flexible blanket & pipes)
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Geysers use 35 - 40% of a households
energy
System including pipes!
Reduced heating cycles
No switching on/off
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Heat loss saving
 Geyser blanket
 Pipe insulation
 Total savings
21%
37%
58%
Savings can vary depending on the length of
the pipes insulated and the thermostat setting.
Thermostat setting should ideally be 55ºC
SANS 204 Energy Efficiency in Buildings
• Far more comprehensive than the building regulations
and SANS 10400 – XA
• Requirements significantly more stringent
• In the longer terms regulation to be upgraded and
trend toward SANS 204
• It is a voluntary standard
• Basic minimum for green star rating
Thermal conductivity, (K-value)
• All materials conduct heat, some better than
others. Good insulation materials must have a
LOW conductivity.
– Eg. The heat from one side of a wall must travel
very slowly towards the other side of the wall.
• Thermal conductivity is calculated in W/mK
(Watts per meter Kelvin degrees), therefore if
two products with similar densities are tested
at the same temperature and one has a K
value of 0.040 W/mk and the other has a K
value of 0.045 W/mK, the material with the
lower K value insulates better.
Thermal conductivity, (K-value)
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The ability of a product to conduct heat
– Steel is a good conductor of heat
– Wood is a poor conductor
Calculated in W/m.K (Watts per meter Kelvin degrees)
– K values of typical building materials
Typical Building Products
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K value ( W/m.K)
Corrugated steel roof sheets
1.000
Clay roof tiles
1.150
Gypsum ceiling board
0.170
Wooden roof truss
0.120
Polyester ceiling insulation ( 10 kg/m³)
0.045
Glasswool ceiling insulation ( 12 kg/m³)
0.040
Glasswool ceiling board ( 50 kg/m³)
0.032
The lower the K value the lower the heat flow through the product
Thermal resistance, (R-value)
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The ability of a product to resist the transfer of heat
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To calculate the R value you need to know
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(R value =
) Thickness in meters
The Thermal conductivity (K value) of the product
The product thickness
K value
– Calculation of R-Values for typical Roof/Ceiling Construction Products
Material
K-Value
W/mK
Corrugated Roof Sheet
Thickness
mm
m
R-Value
m²K/W
43.000
0.8
0.0008
0.00002
Clay Roof Tile
1.150
13.0
0.0130
0.011
Wooden Roof Truss
0.120
25.0
0.0250
0.208
Gypsum Plasterboard
0.170
6.4
0.0064
0.038
Glasswool Ceiling Board (50kg/m³)
0.032
25.0
0.0250
0.781
Glasswool Ceiling Insulation (11kg/m³)
0.040
100.0
0.1000
2.500
Polyester Ceiling Insulation (10kg/m³)
0.045
100.0
0.1000
2.222
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Total R-value of a construction element (Wall or roof) can be obtained by adding the R-values of
the different components
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The higher the R value the better the products thermal resistance

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