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.

Rip, Watch and Organize Everything: The Ultimate Media Guide

Details on how to rip, convert, store, and stream all your media—while retaining the highest possible level of quality.

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?

Worldwide Marine and Hydro Projects

See this link from US Dept of Energy for details of current Marine and Hydro projects worldwide.

Save Energy with Smart Windows that tint/untint to sun's heat

Smart windows from SAGE tint and untint based on control signals responding to the heat of the sun. The windows include a solid state electrochromic reaction, controlled through a low voltage DC power supply. When the coating darkens, the sun’s light and heat are absorbed and subsequently reradiated from the glass surface – much the way low-emissivity glass also keeps out unwanted heat.

Monday, April 4, 2011

Energy Saving Tips for Small Business

Seee some Energy Saving Tips on how you can save energy in your home, small business or farm

Prospects for one million EVs in US by 2015

Barack Obama has an ambitious target to have one million Electric Vehicles on the road in US by 2015. Read how the recent events in Japan and Middle East might impact the success of this target.

Top 10 Uses for Twitter

Have you ever wondered what you can use Twitter for to help your business - read this article for some valuable suggestions.

What is a Passive House?

A passive house is one in which a comfortable interior climate can be maintained without active heating and cooling systems. Read more about how the requirements for a Passive House can be achieved.

All passive houses have to be modelled with the Passive House Planning Package from the Passivhaus Institut.

Friday, April 1, 2011

Innovative Deepwater Platform Aims to Harness Offshore Wind and Wave Power

Principle Power, Inc, of Seattle, have a device known as the WindWaveFloat, will combine their floating offshore wind turbine platform with wave energy convertors, so the system can simultaneously generate electricity from the wind and the waves.

Automated Backup System for your computers

See how to create an automated backup system for your computers from Adam Pash

Thursday, March 31, 2011

Brighton View - A-Rated Home

Casa Buí has carried out the BER assessment on 1 Brighton View, Harrison Row, Rathgar, Dublin 6.

The house has state of the art energy performance achieving A3 rating, and extremely close to A2. See details of the technology included in the house.

Top Tips for Extending or Renovating

See some Top Tips for Extending and Renovating from Home Architects Boris deSwart and Greg Tisdall.

Technology Trends for 2011

Daniel Burrus has published his Top 16 Technology Trends for 2011.

Green Computing

There are many ways that Energy can be saved in the computers that we use. Read this article from Chris Barnatt for an introduction to Green Computing.

Cloud Computing

Casa Buí can assist you with your Cloud Computing application. Read this article for an Introduction to Cloud Computing. Get started by accessing 5GB on-line storage at Amazon. Sign up for Google Apps and make use of many applications to help your business here .

How to Build a Green PC

Watch this video for instruction on how to build a Green PC:

Energy Savers: Home Energy Assessments

Details on benefits of Home Energy Audit, as well as how to carry out a DIY Energy Audit of your home:

Home Efficiency Blog : Best Way to Boil Water

Blog: Home Efficiency Blog Post: Best Way to Boil Water Link:

Wednesday, March 30, 2011

Casa Bui Homepage

Casa Bui home page can now be found at a new location Also now using the latest Joomla CMS version with new functionality added.