Friday, May 6, 2011

Certified Data can Optimise your BER Value

Casa Bui has written before about how to retrofit to Passive House Standard, but even if you are not trying to reach this level of energy performance for your dwelling, you will want to get the best possible energy value from your investment in improving your home.

Casa Bui has much experience of BER assessments that have been delayed or impacted negatively by the lack of certified evidence of the energy performance of different building elements that have been incorporated into a home, often times with the best of intentions, and at significant cost. The BER Assessment is carried out per the DEAP procedure which requires certified data for all building elements. In the absence of the satisfactory certifications, default values must be taken which can lead to a significant negative impact on your BER value.

It is an altogether more thorny process to try and get these certifications retrospectively when the elements have been purchased and installed or integrated into your dwelling. Casa Buí recommends that obtaining these certifications be part of your planning and materials selection process.
Outlined below is a list of items that we recommend you take into account if included in your home energy performance upgrade.

Heating System Efficiency

The heating system efficiency plays a significant role in determining your BER value so your aim should be to maximise the certified seasonal efficiency of this system. You should verify that your proposed boiler is listed in either the SEAI HARP database or the UK SEDBUK system. Heat Pumps are especially problematic in this regard as there are only a handful of systems added to the SEAI system at this stage. Currently there is an interim method in place for determining the Coefficient of Performance of the Heat Pump but this data needs to be certified as tested to EN14511-2 by an accredited laboratory or organisation. Manufacturer declared data is insufficient and the default value of 250% must be taken in the absence of actual values that can be the range of 300-350%.

Potential Impact 5 to 10 kWh/m2/yr

Windows and Doors

If you have invested significantly on state of the art windows with high solar gains and very low u-values, you want to ensure that you are getting credit in the BER Assessment for these. Once again Manufacturer declared data needs to be backed up with certificates of testing carried out as per ISO 10077 by an accredited laboratory or organisation. These tests will most likely have been carried out on windows (1.48 high * 1.23 wide) and doors of standard dimensions. For your build, you will require these certificates, and also declarations from the Manufacturer that the u-values claimed for your windows are based on the Test Certificates, and have been calculated per ISO 10077.

Potential Impact 3 to 5 kWh/m2/yr

Thermal Bridging

Default value for existing house is 0.15 W/m2K  whereas new build can be taken as 0.11W/m2K. However a value of 0.08 W/m2K if your architect/builder can certify that the construction meets ‘Limiting Thermal Bridging and Air Infiltration - Acceptable Construction Details’’ ( ) as referenced in Building Regulations 2008 TGD L.

If you have invested heavily in state of the art technology to get the thermal bridging in the region of 0.03 W/m2K, the actual value for Thermal Bridging may also be calculated using numerical modelling or measurement. You will need the relevant certifications from your architect or builder in order to obtain full credit for your efforts in minimising thermal bridges in your home.

Potential Impact 5 to 10 kWh/m2/yr

Hot Water Cylinder

If the manufacturer of the cylinder can certify the cylinder heat losses in kWh/day, there can be a benefit accruing as against the default values

Potential Impact 1 to 2 kWh/m2/yr

Solar Thermal Panels

Solar panel performance can be taken from the HARP Database or from certification of testing to IS EN 12975-2 Thermal solar systems and components – Solar collectors – Part 2: Test methods.

Potential Impact 3 to 5 kWh/m2/yr

Wednesday, May 4, 2011

Fundamentals of Retrofitting to Passive House Standard

The following list outlines some fundamental aspects of retrofitting a dwelling to meet Passive House Standard:

  1. Well insulated building envelope - adding external insulation to walls to reach u-values of 0.1 W/m2K for walls and roofs.
  2. High energy performing windows and doors - perhaps triple glazed windows.
  3. Minimised heat loss through thermal bridges (i.e. un-insulated joint sbetween walls, floors/walls, ceilings/adjacent walls, windows/walls, etc) - adding insulation where thermal bridges can occur.
  4. Significantly reduced structural air infiltrations, eliminating cold draughts and associated comfort losses. Passivhaus Standard is reached when there are less than or equal to 0.6 air changes per hour @ 50 Pascal pressure.
  5. Optimal use of passive solar and internal heat gains - south facing windows, boiler located within the building envelope, etc.
  6. Introduce renewable energy technologies such as solar thermal heating.
As more people elect to retrofit to Passive House Standards, the costs will no doubt reduce. Currently, the costs associated with retrofitting to Passive House Standard are estimated to be an additional EUR80-150 per square metre, or an additional 10-15% onto the cost of retrofitting to current building standards.

The benefits of retrofitting to Passive House Standard include:
  • Thermal comfort equivalent to a conventional new dwelling
  • Improved air quality due to the ventilation system
  • Drastically reduced energy bills
  • Significantly improved air-tightness
  • Elimination of structural damage due to thermal bridges and mould problems

To assist towards some of the cost of your Passive House Retrofit there are grants available:

Monday, April 18, 2011

Building Energy Rating Estimator

Casa Buí has developed a tool to estimate the Building Energy Rating of a domestic dwelling. Based on a selection of dwelling characteristics, the tool can estimate the BER Value and an estimate of the Annual Energy Consumption.

The tool also gives some suggestions on how to improve the BER estimate. While it does give an indication of the BER value, it is a guide only and is based on general assumptions about a multitude of other characteristics of a dwelling. To get an accurate value for your dwelling, Casa Buí's Energy Assessors can carry out a comprehensive BER Assessment on your dwelling.

Monday, April 11, 2011

Solar Photovoltaic Power - Continues to grow investment and output

The previous week has seen announcements of many new solar projects in the United States, the size of each continuing to grow. The technology continues to drop in price and the decision by GE to build a new plant to manufacture solar panels from cadmium-tellurium (Cd-Te) thin film pads is sure to result in wider adoption in the years ahead. GE is one of the largest manufacturers of wind turbines worldwide and has been long holding its fire on how to get involved in solar technology.

Solar continues to grow quickly, a result of rapidly falling panel prices and state incentives. Also, solar panels produce power during the heat of the day, when the demand from the grid is at its highest and power prices are high. Wind typically blows strongest at night, and has to compete with lower wholesale power rates. A recently released report on wind power output in Scotland has detailed that the output is not meeting previous expectations for both output level and reliability.

The recent events in Japan will have a significant impact on expansion of Nuclear Energy which recently had been making large inroads due to the fact that it does not produce any greenhouse gases. China is also striving to reduce its reliance on coal to reduce its CO2 emissions. Germany is also planning to accelerate decommissioning of its nuclear power plants - it had previously planned to phase them out within 25 year. All these developments bode well for the solar industry.

Solar power in off-grid applications is also contributing to quality of life in rural areas of Cambodia in the form of independent household supplies. Solar power recharges batteries during the day which can be used to supply four hours of lighting and TV for a typical family.

Casa Buí provides engineering services in Solar PV systems design and installation. SEAI have a Solar Power Calculator and a Best Practice Guide that can assist you in deciding if this is the project for you. While there are grants available for Solar Thermal installations in Ireland, there currently are no grants available towards the cost of Solar PV installations.

Wednesday, April 6, 2011

LTE (4G Mobile) is coming, but what will it bring?

3GPP Long Term Evolution (LTE), is the latest standard in the mobile network technology tree that produced the GSM/EDGE and UMTS/HSPA network technologies.

The Global Mobile Suppliers Association reported on Tuesday (April 5) that 196 carriers in 75 countries are investing in LTE at some level. The report says 140 of those operators will deploy commercial LTE systems in 56 countries, up 118 percent from a year ago, and 56 other carriers are conducting LTE trials. It estimates at least 73 LTE networks will be in commercial service by the end of 2012.

It will extend from end user data plans to cellphones, back-end systems and the chips, IP cores and patents that make them work. But it remains to be seen just how those changes will play out.

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The best Cloud Storage solution?

We published a link recently for details about accessing a free 5MB of storage on Amazon Cloud Drive. There are other options like SkyDrive, Dropbox, as well as Amazon. But which is best?