Extra Low Energy Housing in Ireland How far should we go to the Passive House? Jonathan Jennings Head of R&D Kingspan Century Homes

Transcription

1 Extra Low Energy Housing in Ireland How far should we go to the Passive House? Jonathan Jennings Head of R&D Kingspan Century Homes

2 Current Status % CO 2 emissions Transport 30% Agriculture 2% Housing 26% Industry 23% Tertiary 19%

3 Why Change Ireland has the second lowest energy loss through walls, behind Sweden, and the lowest loss of energy through roofs. - Ireland's insulation standards for new dwellings are now amongst the highest in the EU Dick Roche, the Minister for the Environment, Heritage and Local Government. May 2005

4 Here s Why

5 Here s Why

6 And the Future

7 And the Future Oil will diminish, prices will increase Gas supply cannot be guaranteed Energy will become the focus for a new cold war of literal meaning Coal and Peat are CO 2 Intensive No appetite for Nuclear Increased efficiencies from Large scale combined cycle gas turbines (CCGT) will have limited impact Renewable energy on micro and macro levels need to be commissioned along with grid upgrade

8 The Answer Reduce energy demand of each sector Focus on other sources of energy Residential Gas (Large Scale CCGT) Renewable Bio Energy Possibility of Nuclear Too much focus on supplying energy to energy hungry dwellings Need to invest in the building fabric and reduce energy demand New Generation of Low Energy Demand Buildings are required both in New Build and Retro Fit

9 The Consequences Impending Kyoto Fines Potential of 4.3 Billion by 2012 (2 % of GDP)

10 The Consequences Climate Change In medium term higher peak summer temperatures (50 Years) In the long term a possible shift in the North Atlantic Drift with lower average temperatures (50 + Years) 11% change in rain fall Higher humidity Requirement for more flexible buildings

11 Low Energy Demand Buildings Low Energy Demand Buildings The designer at design and construction stages deliberately incorporates a well Insulated Fabric, Air-tightness, Mechanical Heat Recovery Ventilation, and Solar gains with due consideration to the orientation of the building.

12 Was ist ein Passivhaus? Like most things German its efficient Improvement on the Low Energy House

13 Passive House Definition? A passive house is a building in which a comfortable interior climate can be maintained without active heating and cooling systems Adamson & Feist 1988 "Passive Houses" are buildings which assure a comfortable indoor climate in summer and in winter without needing a conventional heat distribution system. To permit this, it is essential that, under climatic conditions prevailing in Central Europe, the building's annual space heating requirement does not exceed 15 kwh/m 2 a Feist, Peper, Görg 2001

14 What is a Passive House The standard has been named "Passive House" because the passive use of free heat gains delivered externally by solar irradiation through the windows and provided internally by the heat emissions of appliances and occupants essentially suffices to keep the building at comfortable indoor temperatures throughout the heating period

15 What is Passive House? The passive house concept A building in which the energy demand is reduced by highly Insulated Fabric, Air-tightness, Mechanical Heat Recovery Ventilation. Uses the free thermal gains delivered by solar irradiation externally & thermal gains from appliances and occupants internally, Achieves economic thermal comfort in summer and in winter without needing a conventional perimeter heat distribution system. The fresh air supply distributes the remaining space heating requirement solely by post heating (or post cooling) of the fresh air mass, which is required to meet regulatory indoor air quality conditions. It is essential that under climatic conditions prevailing in Central Europe, the building does not exceed 15 kwh/(m²a) space heating requirement, 10 W/m² constant heating-load, 42 kwh/(m²a) annual total amount of active energy input 120 kwh/(m²a) total energy requirement for space-heating, domestic hot water and household appliances

16 Specific Energy Consumption Source CEPHEUS

17 Passive Design Based on Climate Ventilation has to deliver the fresh air required for acceptable indoor air quality It is possible to use this quantity of air to heat (and cool) the house In principle this is possible, but the maximum heat load delivered by this concept is very low

18 Passive Design Based on Climate 30 m³/h (8.33 l/sec) is a minimum air rate per person to maintain a reasonable indoor air quality 4 person Household this equates to 120 m³/h Including infiltration this gives 0.55 Fresh ACH Too Low? With 120 m³/h * 30 K (Delta T) = 1.2 kw Hence, 100 m 2 House heat loss cannot be greater than 12 W/m 2 Passive House Design Heat Loss is 10 W/m 2 Independence of the external climate allows flexibility and Passive Houses to be insulated to a different level: More insulation in Frieburg, less in Dublin.

19 Universal Passive Design It would be a mistake to just copy the European passive house design, especially the details used for insulation, windows and ventilation in a completely different climate There is a specific building tradition in different European countries and there are specific climatic boundary conditions Therefore, the specific solution for a passive house has to be adapted to the country and the climate under consideration

20 And the Solution for Ireland? The Passive House has been designed for the Central European Climate Given that the Irish climate is much milder than that of Central Europe What are the components that make up a Passive House in an Irish Climate? Does the Passive House concept have a role in Irish housing policy now or in the future?

21 Why build Passive in Ireland? Cost-efficient way of minimizing the energy demand of new buildings in accordance with the global principle of sustainability Improves the comfort experienced by occupants Creates the basis on which it is possible to meet the remaining energy demand of new buildings completely from renewable sources while recognising the limited availability of renewables and the affordability of extra costs Possible to create CO 2 Neutral buildings with no contribution to GHG emissions for the life time of that building

22 Climate Data Source Passive House Institute

23 Passive Design Irish Climate Fresh Air Requirements 30 m³/h (8.33 l/sec) is a minimum air rate per person to maintain a reasonable indoor air quality according to Din standard 12 l/sec is the min according to ASHRAE (Domestic) 43.2 m³/h is a minimum air rate per person With 173 m³/h * 30 K (Delta T) = 1.73 kw Hence, 100 m 2 House heat loss cannot be greater than W/m 2 Note: The air flow rates may need to be higher!

24 Passive Design Solution for the Irish Climate European Passive Design requires 10 W/m² heat load (10 W/m² over 100 m² = 1 kw) over 20 K = 50 W/K Our design U values will bring us to 25 W/ m² heat load (25 W/m² over 100 m² = 2.5 kw) over 20 K = 125 W/K 2.5 kw Vs 1 kw This is due to the higher U Values Additional 1.5 kw is delivered by Solar Panels

25 Solar In the Passive House concept, Solar Panels are required for hot water anyway, For an increased area of Solar Panel space heating load can be reduced Ventilation system is there already so can act as heat distribution system We now only need to incrementally change the building structure to achieve our Passive House Standard

26 The Central European Passive Solution Wall Roof 0.10 W/m 2 K 0.08 W/m 2 K Floor 0.09 W/m 2 K Windows 0.85 W/m 2 K Doors 0.08 W/m 2 K

27 Passive House Design Concept not a design Passive design is limited due to solar gain

28 Vernacular Irish Passive Design

29 3 Main Factors European Passive House Maximum heat retention through the fabric Energy efficient heat recovery ventilation Passive solar heating There will always be a back up boiler linked to the ventilation system

30 Insulation Excellent thermal insulation as a basic precondition to the Passive House standard Control the fabric heat losses Prevent Thermal Bridges

31 Reduced Thermal Bridges Some thermal bridges cannot be avoided The actual heat losses caused by thermal bridging can be computed using multidimensional heat flow programmes Time and commonsense can go a long way to removing thermal bridging Based on a few simple rules

32 Reduced Thermal Bridges Where possible, maintain and do not interrupt the thermal envelope Where an interrupted insulating layer is unavoidable, thermal resistance in the insulation plane should be as high as possible e.g. aerated concrete or timber At building element junctions, insulating layers should meet without any gaps. Insulating layers should join without interruption or misalignment or any gaps what so ever

33 Reduced Thermal Bridges Typical Floor Wall Junction Cavity Wall Construction

34 Reduced Thermal Bridge Typical Floor Wall Junction Irish Passive House

35 Air-tightness The movement of air into and out of the building which is not for the specific and planned purpose of exhausting stale air or bringing in fresh air Typical houses built today lose 50% of the total heating loads as a result of uncontrolled air leakage Air leakage often leads to ingress of pollutants, inability to heat or cool localised zones within a building and occupier complaints of draughts and discomfort

36 Air-tightness Natural Ventilation cannot be controlled or filtered and will not provide adequate or evenly distributed ventilation It is generally at its most severe during the winter and has least impact during the summer periods This is generally the opposite of the requirements for mechanical ventilation systems within airtight, well insulated buildings

37 Air-tightness Europe Air leakage is measured as a rate of leakage per square metre of external envelope per hour at an artificial pressure differential through the envelope of 50 Pa Need to achieve ACH infiltration Pa (Current German Standard) Air permeability: this includes all the external surfaces, and is the perimeter used to define the leakage standards in UK Building Regulations Part L Expressed as (m 3 /h)/m 50 Pa Building example 5 m * 10 m * 5.2 m = 260 m (m 3 /h)/m 50 Pa

38 MHRV Passive House is a system You cannot remove an element of any system without affecting the system in another area You cannot have an airtight house with out Mechanical ventilation If ventilation is a requirement it should be heat recovery ventilation with efficiencies of at least 75% HRV is the Key to reducing the ventilation losses in an airtight building

39 Thermal Capacity Thermal capacity can be almost as significant as insulation levels in controlling the energy demand in intermittently occupied buildings The rate of heat storage is limited by the surface heat transfer characteristics The effectiveness of thermal mass is as much to do with surface area as it is with heat capacity of the materials

40 Balanced Thermal Capacity With a Thermal Capacity of less than 10 kwh per degree C, a rapid response and control of the house as a system results Faster response allows the temperature to move reasonably quickly in response to energy input from the solar assisted Heating & Ventilation system House must be responsive to peoples flexible lifestyles In total, less energy required to bring the house to a desired temperature

41 Windows The window U-value is a critical factor in achieving the performance required. Required window standards do not represent premium products as shown in TM 29 The target overall window U-values ( W/m 2 K) are minimum standards in many European countries 1.4 W/m 2 K is required Source TM 29 CIBSE & DTI

42 Summer Time The principal function of the advanced envelope in summer is to reduce heat and solar gains The levels of insulation applied to reduce heat loss in winter are effective in limiting conduction gains from high sol-air temperatures Consequently, the main additional requirement is to limit solar gain through glazing

43 Solar Gain "Passive House" is passive as it utilises free heat gains delivered externally by solar irradiation through the windows and provided internally by the heat emissions of appliances and occupants Our proposal here is to deliver the Solar irradiation not primarily through the windows but air solar panels on the roof

44 Solar Gain The Ventilation system has potential to deliver free cooling and active cooling as necessary Consequently, the main additional requirement is to limit solar gain through glazing Moving the Solar gain to the Roof Mounted Panels makes sense With a balanced thermal capacity of 10 kwh/k the effectiveness of the heat gains from the solar collectors in winter and the air cooling by the HRV system in summer is at a maximum With this controllable system, the heating and cooling loads are reduced to a minimum allowing ultimate flexibility

45 Perimeter Heating Perimeter heating is unnecessary in Passive Houses equipped with MHRV Removing perimeter heating can significantly improve the cost effectiveness of Passive Houses Cost saving of the terminal units (equipment and installation) Cost saving on the distribution system. Frees valuable perimeter space Flexible partitioning arrangements. Additional space can add significant value to the project.

46 Costs The improved construction quality of the building envelope and the highly efficient ventilation systems in Passive Houses require extra investment If the approach is pursued rigorously, this is counterbalanced by investment cost savings for the no longer necessary conventional heating system However, in most sub-projects of CEPHEUS it was not possible to reduce the overall costs of building services In total, the extra construction and engineering system investment was found to be between 0% and 17% of the pure construction (Built in the Mid 1990 s)

47 Costs Source Passive House Institute

48 Passive House in Ireland What lessons can we learn from the European Passive House? What are the elements required for an Irish Climate? What is the precedence? Where should housing in Ireland go to over the next 10 years?

49 Requirements for Ireland Actual U Values (Must( be achieved in practice) Wall Roof Pitched Floor 0.20 W/m 2 K 0.16 W/m 2 K 0.20 W/m 2 K 0.16 W/m 2 K Windows 1.4 W/m 2 K Doors 1.4 W/m 2 K

50 Air-tightness Ireland Need to achieve 0.1 ACH infiltration 2 50 Pa Building example 5 x 10 x 5.2 = 260 m 3 Expressed as 2.03 (m 3 /h)/m 50 Pa

51 Irish Passive Difference Main difference in the Kingspan Century Passive solution is we can utilise the air solar collectors for space heating, ventilation and for domestic hot water No excessive south facing glazing suits any design Summer cooling must be dealt with, The ventilation system will allow this Concept reduces the requirement for such high levels of super insulation Need to minimise deviation from accepted methods of building

52 Kingspan Century Key Design Concepts Highly insulated Wall Construction Airtight Construction Balanced Thermal Capacity Heat Recovery /Air Solar Heating & Ventilation Integrated Solar Hot Water Carbon Neutral Heating

53 Kingspan Century 4 Pillars for Passive Design 1. Fabric Heat Loss Through Insulation 2. Control Ventilation and Infiltration Through Air tight construction 3. Integrated Air Solar Collectors 4. Balanced Thermal Capacity

54 Kingspan Century Passive Design Balance Between insulation levels, costs and the size of the air solar heating and ventilation system. We believe there can be a sensible trade off in this approach Favour a highly insulated house with the air solar collectors and a HRV system but using a wood pellet stove to supply any extra heat and hot water

55 Given our existing CO2 emissions Given our impending Kyoto Fines Given the new EPBD Given Climate Change Given the number of houses we are building Irish Policy Transport 30% Industry 23% Agriculture 2% Housing 26% Tertiary 19%

56 Irish Policy We cannot ignore our responsibility Need incentives for low energy building Scrap Section 23 etc and create Tax Incentives for the low energy buildings we need Reduce VAT on Materials used in a low energy design Use HOT programme to allow the passive house concept to achieve critical mass in the developer house market Set out new low energy building regulations Air-tightness needs to be incorporated at a min 2 50 Pa MHRV to become mandatory with min efficiency 75% Utilisation of Solar Thermal is critical U Values as shown Wall Roof Pitched Floor Windows Doors 0.20 W/m 2 K 0.16 W/m 2 K 0.20 W/m 2 K 0.16 W/m 2 K 1.4 W/m 2 K 1.4 W/m 2 K

57 Irish Passive House? Thank You For Your Attention