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DNV KEMA Shayne Rolfe Principal Sustainable Design


LEARNING OBJECTIVES an overview of the design process for naturally ventilated buildings

1

the tools and modeling process used in the design

2

the impact of engineered natural ventilation on interior design.

3

designing engineered natural ventilation systems

4

case studies.


NATURAL VENTILATION WHY IS IT IMPORTANT NOW California has mandated ZNE for new construction for residential by 2020, commercial by 2030 we see it happening faster Achieving 30% HVAC equipment savings for T24 2012 and onwards will be challenging for many design teams - maybe impossible with current technology Engineered naturally ventilated buildings could achieve 50-70% HVAC savings above the 30% equipment savings - largely through reduced run times


ANYWHERE AND ANY BUILDING TYPE


THERMAL COMFORT -

MEASUREMENT

PMV/PPD – predicted mean vote/predicted percentage dissatisfied Fanger (1970) model is officially adopted by US to determine thermal comfort in air conditioned buildings. ATC – adaptive thermal comfort model allowances for clothing values & metoblic rates,

Natural ventilation requires a third model studies have determined a direct correlation between comfort and outdoor temperature, seasonal change and the inclusion of mean skin temperature PMV x 0.5


Tools


Climate Consultant

Hours within extended comfort range San Diego - 47% Phoenix - 24% Newport Beach – 52%


TECHNICAL TOOLS & HISTORY

TAS 1990’s 1st bulk airflow tool


TOOLS - INHOUSE DEVELOPMENT


Process Tools


Passive Strategies


NATURAL VENTILATION Natural ventilation - airflow due to wind and buoyancy, through cracks in the building envelope or purposely installed openings Single Sided - generally limited to perimeter zones Cross ventilation - two or more openings on opposite walls, able to cover large zones Stack ventilation – buoyancy driven, large airflow Windcatchers – wind and buoyancy driven, effective in warm/temperate climates Solar induced – using the sun to induce buoyancy, effective in hot climates


DESIGN CONSIDERATIONS Agree to design brief • operational expectations • heat loads • flexibility • comfort tolerance • business culture

Ch2 IMAGE

Plan the airflow path • free area calculations • seasonal changes • pollution • noise sensitivity • night purge • security • core v’s perimeter • identify special areas • ventilation rates • high load zones • treated air • + - pressure zones

Design analysis/tools • estimate driving pressures • wind conditions • daily/seasonal variations • ventilation devices • velocity through openings • robustness • sensitive to use change • code conflicts • control strategies

DO NOT UNDER ESTIMATE THE WORK TO PROVIDE ANALYSIS


FEATURES FEATURES • building form is primary climate control • narrow plan width < 30ft • floor to ceiling ht. >10ft • open plan • solar gain control • controlled internal gains • high thermal capacity • operable windows • vertical/high air intake or exhaust


Case Study


EXISTING INVENTORY

THIS IS WHERE THE NEW MARKET IS


Open Plan

Operable Windows

Air movement Exhaust

before.


before.

after.


Cool Roof- R40

Solar Tubes

Shading

Thermal Chimney

Wall R21 Insulation Thermal Mass

Planting

Shower Tower

Security

Site Generation

Operable Windows


INTERIORS


Exhaust

Air Inlets

External Gains

Edge in â&#x20AC;&#x201C; Center out

External Gains


THERMAL CHIMNEY


CONCEPT


EXPERIENCE – NELHA HAWAII


OPTIONS

A B C


  

13ft above roof level 400 sft of free area exhaust 26,000 cfm


SHOWER TOWER


WHAT IS IT & WHY FEATURES • extend NV effectiveness • passive evaporative cooling • downdraught flow • security • humidifies • architectural form • pioneered in Phoenix


115 110 105

Temperature (째F)

100 95 90 85 80 75 70 01

02

03

04

05

06

07

08

09

10

11

12

13

14

15

16

17

18

19

20

21

22

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25

26

27

28

29

Date: Sun 01/Aug to Tue 31/Aug Air temperature: Unconditioned/Semiconditioned Office Space (dpr phoenix office - scenario 4_augmonth&openingprofile.aps) Dry-bulb temperature: (PhoenixTMY2.fwt)

30

31

01


37


SIZING EQUIPMENT


Questioning assumptions

Skylight condition - not solar tube Revise roof & wall insulation to reduce load

Internal meeting room - how does infiltration occur Space is 100% daylit, why is there lighting load

Does peak design need peak people Define loads

ASHRAE +25% sizing ASHRAE +15% sizing


Results of questioning assumptions Original Load 39.9 tons

Revised Load 25.5 tons

This is a 35% reduction in load


Results


Section diagram illustrating bioclimatic strategies

Solar Chimney

Solatube and Big Ass Fan

Passive Cooling Tower


Overall view of the building at night.


9-13 kWh/sf/yr

18-24

8-12

kWh/sf/yr

kWh/sf/yr

kWh/sf/yr

kWh/sf/yr

kWh/sf/yr

4 9 6


HVAC Energy Cost Savings P E R C E N T

P E R C E N T


LEARNING OUTCOMES 1

the tools and modeling process used in the design Early team involvement - IDP is the primary tool (CFD) Analysis

2

the impact of engineered natural ventilation on interior design. Interiors can no longer be designed in isolation from the systems

3

designing engineered natural ventilation systems The building is the system. Not pieces of equipment The WHOLE team needs to be engaged early

4

case studies. Different solutions, similar outcomes


THANK YOU

Shayne Rolfe DNV KEMA shayne.rolfe@dnvkema.com

Natural Ventilation  

Slides from Lunch+LEED on Natural Ventilation presented by Shayne Rolfe.

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