Chapter 11 Interior Layout of Offices

Transcription

1 Chapter 11 Interior Layout of Offices Building Energy Efficiency Technical Guideline for Passive Design (Draft 1) CK Tang

2 Foreword This document is produced as part of Component 4, Building Sector Energy Efficiency Program (BSEEP) by CK Tang and Nic Chin The views expressed in this document, which has been produced without formal editing, are those of the authors and do not necessarily reflect the views of neither JKR nor UNDP. Comments and opinions from readers are encouraged and please it to either or or comment at our Facebook page: CK Tang August 23, 2012 Page 2 of 9

3 Table of Contents 11 Interior Layout of Offices Key Recommendations Estimating Energy Saved Simulation Model Simulation Results... 8 Page 3 of 9

4 11 Interior Layout of Offices Interior layout of office space influences energy efficiency in building predominantly due to the effect of maximizing the benefit of daylight harvesting. In short, for buildings where daylight harvesting is practiced, the interior design of the office layout will have a significant impact on the energy consumption of the building. Buildings that do not practice daylight harvesting, the interior layout of the office space will have almost no influence in terms of energy efficiency. Since daylight harvesting in building is one of the significant contributor to energy efficiency in tropical climate buildings, it is important that the interior design is made to compliment the daylight harvested in the building. In general the interior design in daylight harvested spaces should consider the followings: 1. Rooms or spaces that rarely require lighting should be located away from daylight spaces. 2. Glare prevention should be given a priority to ensure that daylight can be harvested comfortably (refer to Chapter 4 for details). Individual rooms in offices are normally allocated to higher ranking (senior) staffs. These higher ranked staffs are typically busy people that attend a lot of meetings and conferences, spending much of the time not in their own office room. In addition, it is also common to allocate the best daylight spaces for higher ranking staff. This type of interior layout will then cause daylight to be provided to unoccupied rooms, while at the same time electrical lights are switched on for open space offices that are typically located away from daylight spaces. An energy efficient design alternative is to switch the position of open space offices with the individual offices. This will then ensure that daylight are provided to predominantly occupied open space offices, while individual offices will have its electrical lights switched off when it is not in use. This strategy will reduce electrical lighting and air conditioning energy consumption in these buildings. It should also be taken note that it is still possible to provide view to the outside from the individual offices by ensuring that their internal partitions have windows to look out. The energy impact from such interior design strategy has not been documented for Malaysian climate zone and this chapter will attempt to provide an estimate on energy saving due to the implementation of such interior design strategy Key Recommendations The key objective is to allow as many electrical lights as possible to be switched off for the longest possible time with maintaining visual comfort to the office space. It was found from this study model that up to 3% total energy reduction potential is possible by switching the position of open space offices to the façade to benefit from the daylight harvested and allowing the individual offices based on the assumption that the individual offices are not occupied 50% of the working hours. Chart , showed that there is a linear correlation between the percentages of hours the individual offices are unoccupied to the amount of energy saved due to the switching the location of individual offices into non daylight spaces, while leaving the daylight harvested for the more occupied spaces. Page 4 of 9

5 Percentage of Total Energy Savings 3.5% 3.0% 2.5% 2.0% 1.5% 1.0% 0.5% Chart : Total Building Energy Saved due to placing individual rooms away from façade leaving the open space offices to benefit from daylight harvested spaces ESTIMATING ENERGY SAVED It is fairly reasonable to estimate the energy saved using the factors shown in Table below based on the area of individual office space moved away from daylight spaces. This table assumed that the entire individual office space was daylight in the original scenario. These individual office spaces was then moved away from the daylight spaces, allowing the daylight spaces to be allocated instead for open offices where the building occupants are working on their desk every hour every day, regularly. % working hour individual offices will be empty. Saving kwh/m² per year of moved individual offices. RM Saved Per year Per m² of moved individual offices. 50% % % Table : Energy and running cost saving per m² of moved individual offices from daylight space to non daylight space. Where the daylight space is then provided for building occupants that regularly occupies the space. Calculation Example 1. Use of Table Base Design. Total Individual Office Spaces in Building: 3,000 m². All occupying daylight spaces. Revised Design. Total Individual Office Spaces in Building: 3,000 m² Individual Offices moved away from daylight spaces: 2,000 m² Individual offices remaining at daylight spaces: 1,000 m² Estimated % of working hours individual office room is empty: 50% Estimated cost of renovation to move individual offices away from daylight space and move open offices to daylight space: RM 20,000 Calculations: % Total Building Energy Saved y = x R² = % 0% 10% 20% 30% 40% 50% 60% Percentage of Hours Individual Rooms Not Occupied Page 5 of 9

6 From Table for 50% of working hours individual office room is empty: 12.6 kwh/m² per year. Area of moved individual offices: 2,000 m² Energy Saved per year: 2,000 m² x 12.6 kwh/m² per year = 25,200 kwh/year Electricity Tariff assumed to be RM 0.35 per kwh. Running Cost Saving per year: 25,200 kwh/year x 0.35 RM/kWh = RM 8,820 per year. Estimated Cost of renovation: RM 20,000 Simple Payback = RM 20,000 / RM 8,820 = 2.27 years Simulation Model The standard center cored, square box, 17 floor model of Case 1 from Chapter 3 was use as the case study for this chapter. All the data used are identical to Chapter 3 unless specifically mentioned in this chapter. Page 6 of 9

7 Individual office spaces of 3.7m depth from the façade were assumed. This assumption provided every floor a space of 650 m² for individual offices, while remaining 996 m² were allocated as open space offices. The assumption is that individual office spaces were always allocated for high ranking office staff that are regularly out for meetings and will not spending 100% of the working hours at their own room. While the open office spaces were for lower ranking office staff that are will be spending near to 100% of the working hours at their desk. The following scenarios were tested out: Locating individual office spaces with external façade (taking up 3.7m depth from the façade) with full access to daylight harvesting. Locating individual office spaces near the core without any access to daylight harvesting but may still have views to the outside by ensuring that windows are provided for partitions between office spaces. Page 7 of 9

8 Individual offices were modeled to be unoccupied 50%, 30% and 10% of the building occupancy hours. Open space offices were modeled to be occupied 100% of the building occupancy hours. Case Scenarios Base Case Individual office spaces located with external façade with full access to daylight harvesting. 50% of the building occupancy hours, these offices are empty and electrical lights will be switched off 50% of the time. Case 1 Individual office spaces located with external façade with full access to daylight harvesting. 30% of the building occupancy hours, these offices are empty and electrical lights will be switched off 30% of the time. Case 2 Individual office spaces located with external façade with full access to daylight harvesting. 10% of the building occupancy hours, these offices are empty and electrical lights will be switched off 10% of the time. Case 3 Individual office spaces located near the core of the building without any access to daylight harvesting. 50% of the building occupancy hours, these offices are empty and electrical lights will be switched off 50% of the time. Case 4 Individual office spaces located near the core of the building without any access to daylight harvesting. 30% of the building occupancy hours, these offices are empty and electrical lights will be switched off 30% of the time. Case 5 Individual office spaces located near the core of the building without any access to daylight harvesting. 10% of the building occupancy hours, these offices are empty and electrical lights will be switched off 10% of the time. Case 6 None of the building occupants leaves their desk, therefore no electrical lights will be switched off during occupancy hours except during daylight harvesting Simulation Results The result is as shown in Chart below. kwh/m2/year Building Energy Index % 10% 20% 30% 40% 50% 60% Percentage of Hours Individual Rooms are Not Occupied Individual Offices at Bld Perimeter Individual Offices at Bld Core Chart : Building Energy Index of Various Case Scenarios. Page 8 of 9

9 The energy saved as a result of reduced hours of use of individual offices is clearly indicated when both cases of locating individual offices at the building perimeter and building core. This saving is caused by the switching of electrical lights when the individual rooms are unoccupied. The simulation scenario included the switching off of electrical lights in the individual rooms when daylight is available. However, for the same unoccupied hours of individual rooms, the energy reduction is higher for the case where the individual offices are located at the core. This allows the daylight spaces be used by building occupants that are regularly at their desk and benefits from having the electrical lights switched off. This is an energy efficiency advantage over individual offices at the perimeter where the rooms may not be occupied and yet benefited from daylight harvested. % hours individual offices are not occupied BEI Individual Offices at Building Perimeter (kwh/m²/year) BEI Individual Offices at Building Core (kwh/m²/year) % diff 50% % 30% % 10% % Table : BEI of Simulated Cases If the individual rooms are regularly unoccupied for less than 10% of the time, the total building energy saving potential provided by moving these rooms away from daylight spaces are low (0.7% or less). However, when these individual rooms are regularlly unoccupied up to 50% of the working hours, the saving potential increased to 3.2%. End of Chapter 11 Page 9 of 9